Why is tar used to seal cracks?
Oakum
Oakum can be used to seal cast iron pipe drains. After setting the pipes together, workers pack oakum into the joints, then pour molten lead into the joint to create a permanent seal. The oakum swells and seals the joint, the "tar" in the oakum prevents rot, and the lead keeps the joint physically tight.
Today, modern methods, such as rubber seals (for example, gaskets or o-rings) are more common.
Ozone cracking
Ozone cracks form in products under tension, but the critical strain is very small. The cracks are always oriented at right angles to the strain axis, so will form around the circumference in a rubber tube bent over. Such cracks are very dangerous when they occur in fuel pipes because the cracks will grow from the outside exposed surfaces into the bore of the pipe, so fuel leakage and fire may follow. 
Seals are also susceptible to attack, such as diaphragm seals in air lines. Such seals are often critical for the operation of pneumatic controls, and if a crack penetrates the seal, all functions of the system can be lost. Nitrile rubber seals are commonly used in pneumatic systems because of its oil resistance. However, if ozone gas is present, cracking will occur in the seals unless preventative measures are taken.
Hydraulic cylinder
The seals are considered / designed as per the cylinder working pressure, cylinder speed, operating temperature, working medium and application.
Piston seals are dynamic seals, and they can be single acting or double acting. Generally speaking, Elastomer seals made from nitrile rubber, Polyurethane or other materials are best in lower temperature environments, while seals made of Fluorocarbon Viton are better for higher temperatures. Metallic seals are also available and commonly use cast iron for the seal material.
Rod seals are dynamic seals and generally are single acting. The compounds of rod seals are nitrile rubber, Polyurethane, or Fluorocarbon Viton.
Wipers / scrapers are used to eliminate contaminants such as moisture, dirt, and dust, which can cause extensive damage to cylinder walls, rods, seals and other components. The common compound for wipers is polyurethane. Metallic scrapers are used for sub zero temperature applications, and applications where foreign materials can deposit on the rod.
The bearing elements / wear bands are used to eliminate metal to metal contact. The wear bands are designed as per the side load requirements. The primary compounds used for wear bands are filled PTFE, woven fabric reinforced polyester resin and bronze
Fiberglass mesh
Drywall finishers also use this tape to patch holes. The most common hole in the drywall generally occurs where a doorknob has hit a wall too many times. If it is only slightly damaged, a couple of short pieces of the tape will be formed into a square and placed over the hole. A joint compound will then be applied directly to it. If the hole is too large to patch with fiberglass mesh alone, a piece of metal flashing can be added behind the tape before applying joint compound. Construction work is not the only use for fiberglass mesh.
Tyrannosauridae
William Abler observed in 2001 that "Albertosaurus" tooth serrations resemble a crack in the tooth ending in a round void called an ampulla. Tyrannosaurid teeth were used as holdfasts for pulling meat off a body, so when a tyrannosaur would have pulled back on a piece of meat, the tension could cause a purely crack-like serration to spread through the tooth. However, the presence of the ampulla would have distributed these forces over a larger surface area, and lessened the risk of damage to the tooth under strain. The presence of incisions ending in voids has parallels in human engineering. Guitar makers use incisions ending in voids to, as Abler describes, "impart alternating regions of flexibility and rigidity" to the wood they work with. The use of a drill to create an "ampulla" of sorts and prevent the propagation of cracks through material is also used to protect airplane surfaces. Abler demonstrated that a plexiglass bar with incisions called "kerfs" and drilled holes was more than 25% stronger than one with only regularly placed incisions. Unlike tyrannosaurs and other theropods, ancient predators like phytosaurs and "Dimetrodon" had no adaptations to prevent the crack-like serrations of their teeth from spreading when subjected to the forces of feeding.
Screw
A screw is a type of fastener, in some ways similar to a bolt (see "Differentiation between bolt and screw" below), typically made of metal, and characterized by a helical ridge, known as a "male thread" (external thread). Screws are used to fasten materials by digging in and wedging into a material when turned, while the thread cuts grooves in the fastened material that may help pull fastened materials together and prevent pull-out. There are many screws for a variety of materials; those commonly fastened by screws include wood, sheet metal, and plastic.
Trap rock
Trap rock, i.e. basalt or diabase, has a variety of uses. A major use for basalt is crushed rock for road and housing construction in concrete, macadam, and paving stones. Because of its insensitivity to chemical influences, resistance to mechanical stress, high dry relative density, frost resistance, and sea water resistance, trap rock is used as ballast for railroad track bed and hydraulic engineering rock (riprap) in coast and bank protection for paving embankments. It is also used for the production of cast rock that is used in corrosion and abrasion protection, as for sewage pipes and acid-resistant rocks. Other uses of trap rock include gardening and landscaping, for the production of millstones, for the production of mineral fibres (basalt wool), as a flux in ceramic masses and glazes, for the production of glass ceramics, crushed as a filter aggregate (air filtration of poison gas in ABC bunkers), as filter bed material water treatment facilities, and ground as a soil improvement product. Trap rock has been used to construct buildings and churches: Trinity Church on the Green with trap rock quarried from Eli Whitney's quarry, is a particularly colorful example of a red-orange-brown-colored, natural-faced trap rock. It was also used for foundations and railroad beds in the New Haven area.
Coal tar
Pine tar has historically also been used for this purpose. Though it is frequently cited online as having been banned as a medical product by the FDA due to a "lack of evidence having been submitted for proof of effectiveness", pine tar is included in the Code of Federal Regulations, subchapter D: Drugs for Human Use, as an OTC treatment for "Dandruff/seborrheic dermatitis/psoriasis".
Tap and die
Both tools can be used to clean up a thread, which is called "chasing". However, using an ordinary tap or die to clean threads will generally result in the removal of some material, which will result in looser and weaker threads. Because of this, threads are typically cleaned using special taps and dies made for this purpose, which are known as "chasers". Chasers are made of softer materials and are not capable of cutting new threads, however they are still tighter fitting than actual fasteners and are fluted like regular taps and dies (to provide a means for debris like dirt and rust to escape). One particularly common use is for automotive spark plug threads, which often suffer from corrosion and a buildup of carbon.
List of tar pits
This is a list of notable tar pits throughout the world. Tar pits, which are often covered with dust and leaves can trap animals that step into them. Over time, the skeletons of such animals become preserved as fossils. Some of the largest deposits of fossils exist within tar pits.
Sealcoat
Not all pavement sealcoat are created equal. For example, refined tar-based sealer offers the best protecting against water penetration and chemical resistance. Asphalt-based sealer typically offers poor protection against environmental chemical and harsher climates (salt water). Petroleum-based sealer offer protection against water and chemicals somewhere between the other two sealers. Another difference between coatings is in terms of wear. Again, refined tar-based sealer offers the best wear characteristics (typically 3–5 years) while asphalt-based sealer may last 1–3 years. Petroleum-based sealer falls between refined tar and asphalt.
Tar
In English, German, and French, "tar" is a substance primarily derived from coal. It was formerly one of the products of gasworks. Tar made from coal or petroleum is considered toxic and carcinogenic because of its high benzene content, though coal tar in low concentrations is used as a topical medicine. Coal and petroleum tar has a pungent odour.
Jar
A jar is a rigid, cylindrical or slightly conical container, typically made of glass, ceramic, or plastic, with a wide mouth or opening that can be closed with a lid, screw cap, lug cap, cork stopper, roll-on cap, crimp-on cap, press-on cap, plastic shrink, heat sealed lidding film, an inner seal, a Tamper-evident band, or other suitable means.
Jars are used to hold foods or other solids too large to be removed from or cosmetics, medications, and chemicals too viscous to be poured through a bottle's neck. Glass jars—among which the most popular is the mason jar—can be used for storing and preserving items as diverse as jam, pickled gherkin, other pickles, marmalade, sun-dried tomatoes, olives, jalapeño peppers, chutneys, pickled eggs, honey, and many others.
Knuckle thread
This thread form's good debris tolerance is the source of its use in oilfields, where it provides a leak-free connection in field use. Many European automobiles use a knuckle thread for their "tow eye," an external threaded recess where a steel towing lug can be fitted. For example, some Porsche cars use DIN 405 Rd 20 x 1/8", and some BMW use a thread similar to DIN 405 Rd 16 x 1/8".
Other applications use a knuckle thread's rounded edges to reduce the stress on softer materials at a point of connection. Some linear actuators use a knuckle thread to reduce the wear of the steel leadscrew against a plastic sliding nut. Firefighting respirator standard EN 148-1 "Respiratory protective devices - Threads for facepieces" lists a knuckle thread to connect metal and rubber parts.
Seam sealant
Seam sealing was already performed manually successfully for preventing perforation corrosion in the 1980s. Today used in the OEM automotive industry primarily for the purpose of seals against air leaks and to waterproof sheetmetal overlaps that occur in the assembly of a vehicle. Such overlaps are typically decorative rather than structurally supportive. Accordingly, they are usually only spot welded and this process results in a closure that is not air or water tight.
Plasterer
Laths must be nailed so as to break joint in bays three or four feet wide with ends butted one against the other. By breaking the joints of the lathing in this way, the tendency for the plaster to crack along the line of joints is diminished and a better key is obtained and it provides restraint for the timber frame. Every lath should be nailed at each end and wherever it crosses a joist or stud. All timbers over three inches (76 mm) wide should be counter-lathed, that is, have a fillet or double lath nailed along the centre upon which the laths are then nailed. This is done to preserve a good key for the plaster. 
Walls liable to damp are sometimes battened and lathed in order to form an air cavity between the damp wall and the plastering.
Tiger tail wire
Tiger tail wire (also simply called tiger tail or tiger-tail) is a kind of thin wire encased in nylon often used in beaded jewellery, and that is particularly suited to stringing heavy beads and sharp beads, which tend to fray other kinds of thread. For this reason, tiger tail is the thread of choice for gemstones. Some tiger tail has multiple intertwined wire threads under the nylon coating. The wire threads are made of stainless steel. Tiger tail cannot be fashioned into a knot in order to end a sequence of beads as other kinds of thread can, therefore crimp beads are often used for this purpose instead. Crimp beads are also used as spacers between other beads strung on tiger tail. Among the types of wire used for bead stringing, tiger tail is the most common. Tiger tail is easier to use than many other kinds of thread, and it does not require the use of a sewing needle. Tiger tail has high ultimate tensile strength and is therefore extremely difficult to tear, but if it is creased or twisted, tiger tail has a tendency to kink and then become brittle in the kinked area.
Rebar spacer
Concrete spacers and bar supports are made of the same material as the poured concrete, so thermal expansion and contraction are equal. And because they are the same material, the concrete and spacers will bond. No gaps!
Concrete spacers and bar supports help maintain material integrity and uniformity of the concrete, and provide a cover over the reinforcement that protects against corrosion.
National pipe thread
The taper on NPT threads allows them to form a seal when torqued as the flanks of the threads compress against each other, as opposed to parallel/straight thread fittings or compression fittings in which the threads merely hold the pieces together and do not provide the seal. The various types of pipe threads are designed for use both with or without thread sealants, as particular applications demand. The sealants, where used, are typically thread seal tape or pipe dope (sometimes plumber's putty). As the thread body is tapered (), a larger diameter keeps compressing into a smaller diameter and finally forms a seal (no clearance remains between the crests and roots of the threads because of the taper). This means that NPT fittings should be burr-free and lubricated using a lubricant like lubricating paste or thread seal tape. The use of tape also helps to limit corrosion on the threads, which otherwise can make future disassembly nearly impossible.
Pine tar
Traditionally, hemp and other natural fibers were the norm for rope production. Such rope would quickly rot when exposed to rain, and was typically tarred to preserve it. The tar would stain the hands of ship's crews, and British Navy seamen became known as "tars."
Crew's Hole, Bristol
A tar works site was established by Isambard Kingdom Brunel in 1843 at the bottom of Troopers Hill, known for its distinctive chimney. It provided creosote to be used as a preservative for railway sleepers and by 1863 had passed into the ownership of Brunel's manager, William Butler. At the turn of the 20th century, the works were used to manufacturer tarmac for roads, which became its main use. British Steel Corporation (BSC) took over running of the tar works in 1970. Under their ownership, it expanded to be one of the most modern in Europe, allowing a continuous 24/7 production of creosote, road tar and smokeless fuel, among other products. It continued to operate until 1981, by which time it had stopped producing road tar and become primarily a distillation unit. After closure, the works lay derelict for some years, until the area was redeveloped as Quayside Village in 1989.
Archibald Cochrane, 9th Earl of Dundonald
Cochrane hoped that he would be able to sell tar as a sealant for the hulls of ships to the Royal Navy. After contacts with the British Admiralty were made, a test was performed on a buoy. The buoy was coated on one side and left uncoated on the other. After some time the uncoated half was leaking and full of worms and barnacles, while the treated half was in quite good condition. A patent for his invention was drawn up, while the family estates were used as collateral.
Tack cloth
Tack cloth (tack rag; tac cloth) is a specialized type of wiping cloth that is treated with a tacky material. It is designed to remove loose particles of dust, dirt and lint that would contaminate a surface that is to be painted, coated, laminated, photo-etched, or otherwise finished.
Slickline
This type of tool can be extended and closed rapidly to induce a mechanical shock to the tool string. This shock can induce certain components such as plugs to lock into place and then unlock for retrieving. Jars are commonly used to shear small brass or steel pins that are put in place to function certain down-hole tools at a certain moment. The operator can use the jars to shear the pins at a predetermined depth. Spang jars are manually operated by the wireline operator who either lifts or lowers wire rapidly, requiring a great deal of expertise.
Properties of concrete
Concrete cracks due to tensile stress induced by shrinkage or stresses occurring during setting or use. Various means are used to overcome this. Fiber reinforced concrete uses fine fibers distributed throughout the mix or larger metal or other reinforcement elements to limit the size and extent of cracks. In many large structures joints or concealed saw-cuts are placed in the concrete as it sets to make the inevitable cracks occur where they can be managed and out of sight. Water tanks and highways are examples of structures requiring crack control.
Talc
Talc is used in many industries, including paper making, plastic, paint and coatings, rubber, food, electric cable, pharmaceuticals, cosmetics, and ceramics. A coarse grayish-green high-talc rock is soapstone or steatite, used for stoves, sinks, electrical switchboards, etc. It is often used for surfaces of laboratory table tops and electrical switchboards because of its resistance to heat, electricity and acids. Talc finds use as a cosmetic (talcum powder), as a lubricant, and as a filler in paper manufacture. It is used to coat the insides of inner tubes and rubber gloves during manufacture to keep the surfaces from sticking. Talc, with heavy refinement, has been used in baby powder, an astringent powder used to prevent diaper rash. The American Academy of Pediatrics recommends that parents not use baby powder because it poses a risk of respiratory problems, including breathing trouble and serious lung damage if the baby inhales it. The small size of the particles makes it difficult to keep them out of the air while applying the powder. Zinc oxide-based ointments are a much safer alternative.
Hydraulic fracturing
The proppant is a granular material that prevents the created fractures from closing after the fracturing treatment. Types of proppant include silica sand, resin-coated sand, bauxite, and man-made ceramics. The choice of proppant depends on the type of permeability or grain strength needed. In some formations, where the pressure is great enough to crush grains of natural silica sand, higher-strength proppants such as bauxite or ceramics may be used. The most commonly used proppant is silica sand, though proppants of uniform size and shape, such as a ceramic proppant, are believed to be more effective.
Tar pit
Animals usually cannot escape from the asphalt when they fall in, making these pits excellent places to excavate bones of prehistoric animals. The tar pits can trap animals because the asphalt that seeps up from underground forms a bitumen pit so thick that even mammoths could not free themselves before they died of starvation, exhaustion from trying to escape, or exposure to the sun's heat. Over a million fossils have been found in tar pits around the globe.
Security seal
Bolt seals are used to secure shipping containers, trucks and trailers. A bolt seal used for securing containers must conform to the ISO 17712 high security seal in order to be accepted by customs all around the world in ocean shipping. The C-TPAT (Customs Trade Partnership Against Terrorism) specifies ISO 17712 compliant security seals to be used. Bolt seals are generally closed by hand (by pushing the seal body and head together) and opened with the use of bolt cutters. This gives a strong and secure seal for transportation, while remaining convenient for staff in ports and warehouses.
Trap primer
A trap primer (or trap seal primer) is a plumbing device or valve that adds water to traps. The water seals in traps are needed to prevent sewer gases from entering buildings, but because this water is exposed to the air, it is subject to evaporation over time in infrequently used floor drains, leading to the release of sewer gas into the environment. The trap primer mitigates this problem by injecting water, either directly or indirectly, into the trap to maintain the water seal indefinitely.
Tar (computing)
A tarbomb, in hacker slang, is a tar file that contains many files that extract into the working directory. Such a tar file can create problems by overwriting files of the same name in the working directory, or mixing one project's files into another. It is at best an inconvenience to the user, who is obliged to identify and delete a number of files interspersed with the directory's other contents. Such behavior is considered bad etiquette on the part of the archive's creator.
Screw
The materials are usually carbon steel substrate with a coating of zinc galvanization (for corrosion resistance). The zinc coating may be bright (electroplated), yellow (electroplated), or dull gray hot-dip galvanized. Lag screws are used to lag together lumber framing, to lag machinery feet to wood floors, and for other heavy carpentry applications. The attributive modifier "lag" came from an early principal use of such fasteners: the fastening of lags such as barrel staves and other similar parts.
Tar Tunnel
Miners struck a gushing spring of natural bitumen, a black treacle-like substance, when digging a canal tunnel for the Coalport Canal in 1787, or else digging a level in search of coal. The plan, proposed by William Reynolds, was to connect the canal alongside the River Severn to the lower galleries of the mines below the Blists Hill area. After digging some 3,000ft (almost 1 km) into the hill the canal project was abandoned in favour of bitumen extraction. 
The tunnel was a great curiosity in the eighteenth century and bitumen still oozes gently from the brick walls today. Bitumen's chief commercial use at the time was to treat and weatherproof ropes and caulk wooden ships, but small amounts were processed and bottled as 'Betton's British Oil', a panacea remedy for rheumatism and scurvy. After the canal project was abandoned the Hay Inclined Plane was built instead, its base being alongside the canal basin.
Spark plug
Because the spark plug also seals the combustion chamber of the engine when installed, seals are required to ensure there is no leakage from the combustion chamber. The internal seals of modern plugs are made of compressed glass/metal powder, but old style seals were typically made by the use of a multi-layer braze. The external seal is usually a crush washer, but some manufacturers use the cheaper method of a taper interface and simple compression to attempt sealing.
Tar
In Northern Europe, the word "tar" refers primarily to a substance that is derived from the wood and roots of pine. In earlier times it was often used as a water repellent coating for boats, ships, and roofs. It is still used as an additive in the flavoring of candy, alcohol, and other foods. Wood tar is microbicidal. Producing tar from wood was known in ancient Greece and has probably been used in Scandinavia since the Iron Age. For centuries, dating back at least to the 14th century, tar was among Sweden's most important exports. Sweden exported 13,000 barrels of tar in 1615 and 227,000 barrels in the peak year of 1863. Production nearly stopped in the early 20th century, when other chemicals replaced tar, and wooden ships were replaced by steel ships. Traditional wooden boats are still sometimes tarred.
Ninja rocks
Tempered glass, which is used for the side windows of most vehicles, is manufactured with an extremely high surface compressive stress and high internal tensile stress, giving it strength and durability, but also leading it to abruptly shatter into thousands of tiny pieces when it breaks. When thrown with moderate speed at a side-window, a sharp shard of the exceptionally hard aluminium oxide ceramic used in spark plugs focuses the impact energy into a small enough area without blunting to initiate cracking, releasing the internal energy and shattering the glass. However, ninja rocks are ineffective if the shards are insufficiently sharp, thrown with too little energy, or thrown against windshields, as these are made of a laminated type of safety glass, and therefore do not shatter.
Drain cleaner
Galvanized iron is actually steel covered in a protective layer of zinc, but it was soon discovered that this zinc layer naturally corroded due to exposure to the atmosphere and rainwater, as well as cement, runoff, etc. Once corrosion occurred down to the base metal, plaques and rust would form, leading to sediment build-up that would gradually clog these drains. Thus, the first motivation for drain cleaners came to be.
Zipper
This double-mated surface is good at retaining both vacuum and pressure, but the fit must be very tight, to press the surfaces together firmly. Consequently, these zippers are typically very stiff when zipped shut and have minimal flex or stretch. They are hard to open and close because the zipper anvil must bend apart teeth that are being held under tension. They can also be derailed (and damage the sealing surfaces) if the teeth are misaligned while straining to pull the zipper shut.
Bituminous waterproofing
Roofing felt (similar to tar paper) is the base material used to make roof shingles and roll roofing. Used for decades as waterproof coverings in residential and commercial roofs, these bitumen compositional membranes incorporate two layers. The first underside polymer membrane is used as a solid background, often reinforced with glass fibers. Mineral granules make up the self-protective top layer, with a final bituminous mixture encapsulating them both. Typical uses of felt paper are as an underlay(ment) (sarking) beneath other building materials, particularly roofing and siding materials, and is one type of membrane used in asphalt built up roofing (BUR) systems. The purposes are to "...separate the roof covering from the roof deck...shed water...[and] provide secondary weather protection..." Also, the rapid application of roofing underlay protects the roof deck during construction until the roofing material is applied and is required for roofs required to meet Underwriters Laboratory (UL) fire ratings. The separation of the roof covering from the roof deck protects the roof covering from resins in some sheathing materials and cushions unevenness and old nails and splinters in re-roofing applications. The underlayment also sheds water, which penetrates the roof covering from an ordinary leak, a leak from wind-driven rain or snow, wind damage to the roof covering, or ice dams. However, the application of underlays may increase the roof temperature, which is the leading cause of ageing of asphalt shingles and felt paper wrinkles when it gets wet, which (rarely) shows through asphalt shingles. Not installing an underlay may void the roof covering warranty.
Latch seal
A latch seal is a product which helps limit access to private facilities for people without permits. А high level of strength plastic is used for the manufacture of seals. In order to protect are used the unique number which is applied to the case and closing security seal design (an insert). There are various options for the application of a unique number: laser marking (you can’t change the number or erase), pad printing, engraving.
Coal tar
Being flammable, coal tar is sometimes used for heating or to fire boilers. Like most heavy oils, it must be heated before it will flow easily.
Plica (sigillography)
The purpose of the fold is to provide a more secure anchorage for the seal, and to guard against the parchment being torn. Slots were normally cut in the double thickness of parchment, a cord or tag of parchment threaded through them, and the seal attached to that.
Coal tar
A large part of the binder used in the graphite industry for making "green blocks" is coke oven volatiles (COV), a considerable portion of which is coal tar. During the baking process of the green blocks as a part of commercial graphite production, most of the coal tar binders are vaporised and are generally burned in an incinerator to prevent release into the atmosphere, as COV and coal tar can be injurious to health.
Highway engineering
A tack coat is a low viscosity asphalt emulsion that is used to create a bond between an existing pavement surface and new asphalt overlay. Tack coats are typically applied on adjacent pavements (curbs) to assist the bonding of the HMA and concrete.
Nerf bar
A nerf bar is a tubular device fitted to the side of a racecar, typically single-seat race cars that compete on asphalt or dirt oval tracks. A "nerf" is a small, sometimes intentional, collision between two cars in which one driver bumps the other to facilitate a successful pass. The nerf bar protects the sides of the vehicles and also keeps their tires from becoming entangled. If fast-spinning tires come in contact with each other, one or both of the cars may lose control or even become airborne. These are commonly used on Modifieds such as used in the NASCAR Whelen Modified Series, and the wheel pods behind the rear wheels on a Dallara DW12 INDYCAR is often nicknamed the nerf bar because of the similar purpose.
Underlay
"Underlay" is also the term for the material under roofing tiles; this roofing membrane is often made of rubber and is used to seal the roof and prevent leakage. Underlayment used with roofing shingles provides a second layer of water proofing to prevent leaks and is called tar paper, roofing felt, or since the 1990s synthetic underlayment.
Pine tar
Pine tar is widely used as a veterinary care product, particularly as an antiseptic and hoof care treatment for horses and cattle. It also has been used when chickens start pecking the low hen. Applying a smear of pine tar on the wound acts as a natural germicidal/antibacterial and discourages continued attacks on the affected hen due to its foreign texture.
Coal tar
Coal tar was a component of the first sealed roads. In its original development by Edgar Purnell Hooley, tarmac was tar covered with granite chips. Later the filler used was industrial slag. Today, petroleum derived binders and sealers are more commonly used. These sealers are used to extend the life and reduce maintenance cost associated with asphalt pavements, primarily in asphalt road paving, car parks and walkways.
Tack strip
Tack strip (US) (also known as gripper rod (UK), carpet gripper, Smoothedge (Can), tackless strip, and gripper edge) is a thin piece of wood, between long and about wide, studded with hundreds of sharp nails or tacks used in the installation of carpet. They are nailed, tack side up, to the perimeter of the area being carpeted. After the underlay is installed, the carpet is cut to fit, stretched over the area and firmly anchored to the edges of floor via the tack strips. The strip has two functions: first, the tacks grip the carpet and permanently hold it in place and second, the carpet edge is jammed into the gap between the tack strip and the wall which gives it a finished look with little effort. This method allows a high quality, long lasting installation to be completed quickly and easily.
Tar paper
Tar paper has been in use for centuries. Originally felt was made from recycled rags but today felts are made of recycled paper products (typically cardboard) and sawdust. The most common product is #15 felt. Before the oil crisis, felt weighed about 15 pounds per square (one square = 100 square feet) and hence the asphalt-impregnated felt was called "15#" and "15-pound felt". Modern, inorganic mats no longer weigh 0.73 kg/m2, and to reflect this fact the new felts are called "#15". In fact, #15 mats can weigh from 7.5 to 12.5 pounds/sq depending on the manufacturer and the standard to which felt is made (i.e., CGSB, ASTM D227 Standard Specification for Coal-tar saturated Organic Felt Used in Roofing and Waterproofing, ASTM D4990, Standard Specification for Coal Tar Glass Felt Used in Roofing and Waterproofing, or none). Thirty-pound (30#) felt is now #30 felt, and usually weighs 16 to 27 pounds per square.
Rebar
Rebar (short for reinforcing bar), known when massed as reinforcing steel or reinforcement steel, is a steel bar or mesh of steel wires used as a tension device in reinforced concrete and reinforced masonry structures to strengthen and aid the concrete under tension. Concrete is strong under compression, but has weak tensile strength. Rebar significantly increases the tensile strength of the structure. Rebar's surface is often deformed to promote a better bond with the concrete.
Pine tar
Pine tar is combined with gum turpentine and boiled linseed oil to create a wood preservative. First, a thin coat is applied using a mixture with a greater proportion of turpentine. This allows it to permeate deeper into the oakum and fibre of the wood and lets the tar seep into any pinholes and larger gaps that might be in the planks. The tar weeps out to the exterior and indicates where the boat needs the most attention. This is followed with a thicker standard mix. Such treatments, while effective, must be continually reapplied.
Tar (computing)
In computing, tar is a computer software utility for collecting many files into one archive file, often referred to as a tarball, for distribution or backup purposes. The name is derived from "(t)ape (ar)chive", as it was originally developed to write data to sequential I/O devices with no file system of their own. The archive data sets created by tar contain various file system parameters, such as name, time stamps, ownership, file access permissions, and directory organization. The command line utility was first introduced in the seventh edition of unix (v7) in January 1979, replacing the tp program. The file structure to store this information was later standardized in POSIX.1-1988 and later POSIX.1-2001 and became a format supported by most modern file archiving systems.
Concrete cover
National codes also specify minimum cover requirements based on their respective local exposure conditions.
Large cover depths (50–75 mm) are required to protect reinforcement against corrosion in aggressive environments, but thick cover leads to increased crack widths in flexural reinforced concrete members. Large crack-widths (greater than 0.3 mm) permit ingress of moisture and chemical attack to the concrete, resulting in possible corrosion of reinforcement and deterioration of concrete. Therefore, thick covers defeat the very purpose for which it is provided. There is a need for judicious balance of cover depth and crack width requirements.
Break-in (mechanical run-in)
The goal of modern engine break-ins is the settling of piston rings into an engine's cylinder wall. A cylinder wall is not perfectly smooth but has a deliberate slight roughness to help oil adhesion. As the engine is powered up, the piston rings between the pistons and cylinder wall will begin to seal against the wall's small ridges. 
Additionally older design engines had a flat lifter that was pushed by the camshaft lobes. It needs to spin during operation to avoid excessive wear to the camshaft lobe. At idle speeds on a new engine poor machining tolerances could prevent the lifter from spinning and destroy the camshaft. After 20 minutes of wear, or "self machining" at higher engine speeds they would typically be able to spin freely.
Caulk
Modern caulking compounds are flexible sealing compounds used to close up gaps in buildings and other structures against water, air, dust, insects, or as a component in firestopping. In the tunnelling industry, caulking is the sealing of joints in segmental precast concrete tunnels, commonly by using concrete.
Anti-inflammatory
Coal tar has been used for centuries for its anti-inflammatory and analgesic effects. Oral administration for central effects is now rare as coal tar also contains a range of dangerous and carcinogenic compounds, and does not allow for the administration of standardized doses, although some doctors readily utilize coal tar preparations for topical administration (ex. Denorex, Psoriasin) in the treatment of skin conditions such as eczema and atopic dermatitis. Many modern analgesics and anti-inflammatory agents (ex. paracetamol, and its previously used predecessor phenacetin) are derived from compounds which were originally discovered during studies to elucidate the chemicals responsible for the tars reputed health benefits.
Welding defect
A root crack is the crack formed by the short bead at the root(of edge preparation) beginning of the welding, low current at the beginning and due to improper filler material used for welding.Major reason for happening of these types of cracks is hydrogen embrittlement. These types of defects can be eliminated using high current at the starting and proper filler material. Toe crack occurs due to moisture content present in the welded area,it as a part of the surface crack so can be easily detected. Preheating and proper joint formation is must for eliminating these types of defects.
Dental sealant
Dental sealants are a preventive treatment that is part of the minimal intervention dentistry approach to dental care. These sealants are a plastic material placed in the pits and fissures (the recesses on the chewing surfaces) of primary (baby) or permanent (adult) molar and premolar teeth at the back of the mouth. These molar teeth are considered the most susceptible teeth to dental caries due to the anatomy of the chewing surfaces of these teeth, which inhibits protection from saliva and fluoride and instead favours plaque accumulation. This approach facilitates prevention and early intervention, in order to prevent or stop the dental caries process before it reaches the ends stage of the disease, which is also known as the "hole" or cavitation of a tooth. Once the tooth is cavitated, it requires a dental restoration in order to repair the damage, which emphasizes the importance of prevention in preserving teeth for a lifetime of chewing.
Dental dam
A dental dam or rubber dam (sometimes termed "Kofferdam"—from German), designed in the United States in 1864 by Sanford Christie Barnum, is a thin, square sheet, usually latex or nitrile, used in dentistry to isolate the operative site (one or more teeth) from the rest of the mouth. It is used mainly in endodontic, fixed prosthodontic (crowns, bridges) and general restorative treatments. Its purpose is both to prevent saliva interfering with the dental work (e.g. contamination of oral micro-organisms during root canal therapy, or to keep filling materials such as composite dry during placement and curing), and to prevent instruments and materials from being inhaled, swallowed or damaging the mouth. In dentistry, use of a rubber dam is sometimes referred to as "isolation".
Labyrinth seal
A labyrinth seal may be composed of many grooves that press tightly inside another axle, or inside a hole, so that the fluid has to pass through a long and difficult path to escape. Sometimes screw threads exist on the outer and inner portion. These interlock, to produce the long characteristic path which slows leakage. For labyrinth seals on a rotating shaft, a very small clearance must exist between the tips of the labyrinth threads and the running surface. The "teeth" of the labyrinth seal may be on the rotating shaft (Teeth On Rotor - TOR) or on the stator (TOS), or both, in an interlocking configuration.
Breaker bar
A breaker bar is a long non-ratcheting bar that is used with socket wrench-style sockets. They are used to break loose very tight fasteners because their additional length allows the same amount of force to generate significantly more torque than a standard length socket wrench. Their use prevents damage to the ratcheting mechanism of a socket wrench. Often, after the first half turn, the fastener is loose enough to be turned with a socket wrench.
The long handle on breaker bars compared to shorter wrenches allow a larger torque to be generated with the same amount of force.
A breaker bar can be improvised by inserting a wrench into a length of metal pipe to increase the available torque. A pipe used for this purpose is called a cheater bar or snipe.
Self-healing material
Generally, ceramics are superior in strength to metals at high temperatures, however, they are brittle and sensitive to flaws, and this brings into question their integrity and reliability as structural materials.
M_{\mathit n+1}AX_\mathit{n} phase ceramics, also known as MAX Phases, can autonomously heal crack damage by an intrinsic healing mechanism. Micro cracks caused by wear or thermal stress are filled with oxides formed from the MAX phase constituents, commonly the A-element, during high temperature exposure to air.
Crack gap filling was first demonstrated for TiAlC by oxidation at 1200 °C in air. TiAlC and CrAlC have also demonstrated said ability, and more ternary carbides and nitrides are expected to be able to autonomously self-heal. The process is repeatable up to the point of element depletion, distinguishing MAX phases from other self-healing materials that require external healing agents (extrinsic healing) for single crack gap filling. Depending on the filling-oxide, improvement of the initial properties such as local strength can be achieved.
On the other hand, mullite, alumina and zirconia do not have the ability to heal intrinsically, but could be endowed with self-healing capabilities by embedding second phase components into the matrix. Upon cracking, these particles are exposed to oxygen, and in the presence of heat, they react to form new materials which fill the crack gap under volume expansion.
This concept has been proven using SiC to heal cracks in an Alumina matrix, and further studies have investigated the high temperature strength, and the static and cyclic fatigue strength of the healed part. The strength and bonding between the matrix and the healing agent are of prime importance and thus govern the selection of the healing particles.
Tar (string instrument)
The tar appeared in its present form in the middle of the eighteenth century in Persia. The body is a double-bowl shape carved from mulberry wood, with a thin membrane of stretched lamb-skin covering the top.
Forge
A "slack tub" is usually a large container full of water used by a blacksmith to quench hot metal. The slack tub is principally used to cool parts of the work during forging (to protect them, or keep the metal in one area from "spreading" from, for example, nearby hammer blows); to harden the steel; to tend a coal or charcoal forge; and simply to cool the work quickly for easy inspection. In blade smithing and tool making the term will usually be changed to a "quench tank" because oil or brine is used to cool the metal. The term slack is believed to derive from the word "slake", as in slaking the heat.
Zakynthos
The importance of this alliance for Athens was that it provided them with a source of tar. Tar is a more effective protector of ship planking than pitch (which is made from pine trees). The Athenian trireme fleet needed protection from rot, decay and the teredo, so this new source of tar was valuable to them. The tar was dredged up from the bottom of a lake (now known as Lake Keri) using leafy myrtle branches tied to the ends of poles. It was then collected in pots and could be carried to the beach and swabbed directly onto ship hulls. Alternatively, the tar could be shipped to the Athenian naval yard at the Piraeus for storage.
Flat roof
Coal tar is an aromatic hydrocarbon and a by-product from the coking process of the coal industry. It is historically in abundance where coal is used in steel manufacturing. It ages very slowly through volatilization and is an excellent waterproofing and oil resistant product. Roofs are covered by heating the coal tar and applying it between layers of tar paper. It has limitations in regards to its application on dead level or flat roofs with slopes less than 1/4 in 12. It has a tendency to soften in warm temperatures and "heal" itself. It is typically ballasted with gravel to provide a walking surface, however a mineral surface membrane is available. Coal tar provides an extremely long life cycle that is sustainable and renewable. It takes energy to manufacture and to construct a roof with it but its proven longevity with periodic maintenance provides service for many years, with ages from 50 to 70 years not uncommon, with some now performing for over a century. Currently, there are cold process (no kettle is used) coal tar pitch products that almost eliminate all fumes associated with its typical hot process version.
Snow tire
Many jurisdictions in Asia, Europe, and North America seasonally allow snow tires with metal or ceramic studs to improve grip on packed snow or ice. Such tires are prohibited in other jurisdictions or during warmer months because of the damage they may cause to road surfaces. The metal studs are fabricated by encapsulating a hard pin in a softer material base, sometimes called the "jacket". The pin is often made of tungsten carbide, a very hard high performance ceramic. The softer base is the part that anchors the stud in the rubber of the tire. As the tire wears with use, the softer base wears so that its surface is at about the same level as the rubber, whereas the hard pin wears so that it continues to protrude from the tire. The pin should protrude at least for the tire to function properly. Snow tires do not eliminate skidding on ice and snow, but they greatly reduce risks.
Pine tar
Pine tar is used as a softening solvent in the rubber industry, for treating and fabricating construction materials, and in special paints.
Tar pit
A tar pit, or more accurately an asphalt pit or asphalt lake, is the result of a type of petroleum seep where subterranean bitumen leaks to the surface, creating a large area of natural asphalt. This happens because, after the material reaches the surface, its lighter components vaporize, leaving only the thick asphalt.
Sealcoat
Prior to application the surface must be completely clean and dry using sweeping methods and/or blowers. If the surface is not clean and dry, then poor adhesion will result.
Pavement sealers are applied with either pressurized spray equipment, or self-propelled squeegee machines or by hand with a squeegee. Equipment must have continuous agitation to maintain consistency of the sealcoat mix. The process is typically a two-coat application which requires 24 to 48 hours of curing before vehicles can be allowed back on the surface. Once the surface is properly prepared, then properly mixed sealer will be applied at about 60 square feet per gallon per coat.
Some studies that suggest that refined tar sealants are a significant contributor to polycyclic aromatic hydrocarbon levels in streams and creek beds and that the continual application of sealcoats may be a significant factor. As a result, a few municipalities in the United States have banned this material. The same studies also suggest that it can be harmful if ingested before curing and ingesting soil or dust contaminated by eroded coal tar sealant. It is also known to have effects on fish and other animals that live in water.
Stain-blocking primer
Stain-blocking primers are used to cover stains such as watermarks, nicotine (actually tar), markers, smoke, and prevent them bleeding through newly applied layers of paint. They also provide adhesion over problematic surfaces, giving better film leveling, and durability. Commonly used stain-blocking paints include acrylic and alkyd.
Duct tape occlusion therapy
In 1978, Jerome Z Litt was the first to suggest that adhesive tape could be used to treat warts on the fingers. He claimed: "My method is safe, easy, simple, painless, inexpensive, and highly effective. It leaves no scarring or deformed nails. The mystery remains: How and why does this method work? I cannot offer any reasonable or logical explanation. It cannot be all 'hypnotic' or 'suggestive.' Could it be that the airtight occlusion and a chemical reaction set up by the adhesive in the tape might combine to release a chemical or 'toxin' causing the formation of antibodies? Whatever it may be, it works. I recommend that you try it."
Flat tire
One common way to temporarily repair and re-inflate a punctured tire at the roadside is to use a canned tire sealant. The motorist attaches this to the valve, and the compressed propellant inside forces the can's contents through the valve into the tire, a liquid sealant is forced towards the puncture and will seal the puncture. The compressed propellant also inflates the tire. Tire sealant is typically useful on punctures of 3/16in. (5mm) diameter or less. According to research carried out by Continental Tires, 95% of punctures are caused by objects of 5mm or less. Typically, the sealant is a water based latex solution which can easily be removed by a tire repair professional before a permanent repair is made. Canned tire sealants are quick and simple to use and have the added benefit of working when the vehicle is in a dangerous location such as at the side of a busy highway, or on uneven ground.
Glass-to-metal seal
In a matched seal the thermal expansion of metal and glass is matched. Copper-plated tungsten wire can be used to seal through borosilicate glass with a low coefficient of thermal expansion which is matched by tungsten. The tungsten is electrolytically copper plated and heated in hydrogen atmosphere to fill cracks in the tungsten and to get a proper surface to easily seal to glass. The borosilicate glass of usual laboratory glassware has a lower coefficient of thermal expansion than tungsten, thus it is necessary to use an intermediate sealing glass to get a stress-free seal.
Paper cartridge
Paper cartridges were often coated in beeswax, lard, or tallow, which served a number of purposes. It provided some degree of water resistance, it lubricated the paper-wrapped bullet as it was pushed down the bore, and it melted upon firing to mix with the powder residue and make the resulting fouling easier to remove. Since the standard procedure for loading a musket or rifled musket involved biting open the cartridge, this caused problems for those with strict dietary restrictions. The grease used on these cartridges was rumoured to include tallow derived from beef, which would be offensive to Hindus, and pork, which would be offensive to Muslims. The Sepoy soldiers in the employ of the British in India, for example, were largely Hindu, who were forbidden to eat beef, or Muslim, who were forbidden to eat pork. Rumors of the use of lard and tallow in the lubrication of the cartridges they were using were part of the cause of the Indian Rebellion of 1857.
Glass-to-metal seal
Also the mechanical design of a glass-to-metal seal has an important influence on the reliability of the seal. In practical glass-to-metal seals cracks usually start at the edge of the interface between glass and metal either inside or outside the glass container. If the metal and the surrounding glass are symmetric the crack propagates in an angle away from the axis. So, if the glass envelope of the metal wire extends far enough from the wall of the container the crack will not go through the wall of the container but it will reach the surface on the same side where it started and the seal will not leak despite the crack.
Bead breaker
Invented in 1984 by David Allen Dayton. A bead breaker is a tool used for separating tires from rims. The inner-most diameter of the tire that interfaces with a wheel is called the Tire Bead. The tire bead is a thicker section of rubber, and is reinforced with braided steel cable, called the Bead Bundle. The inner-most surface of the tire bead creates the air seal between the tire and rim on a radial-ply tire and a bias-ply tire. Often, the bead can become frozen to the rim after rusting or corrosion occurs, requiring the use of a bead breaker in order to be removed.
History of manufactured fuel gases
The chemical industries demanded coal tar, and the gas-works could provide it for them; and so the coal tar was stored on site in large underground tanks. As a rule, these were single wall metal tanks – that is, if they were not porous masonry. In those days, underground tar leaks were seen as merely a waste of tar; out of sight was truly out of mind; and such leaks were generally addressed only when the loss of revenue from leaking tar "wells", as these were sometimes called, exceeded the cost of repairing the leak.
Tar
In Finland, wood tar was once considered a panacea reputed to heal "even those cut in twain through their midriff". A Finnish proverb states that "if sauna, vodka and tar won't help, the disease is fatal." Wood tar is used in traditional Finnish medicine because of its microbicidal properties.
Glass-to-metal seal
Historically, some television cathode ray tubes were made by using ferric steel for the funnel and glass matched in expansion to ferric steel. The steel plate used had a diffusion layer enriched with chromium at the surface made by heating the steel together with chromium oxide in a HCl-containing atmosphere. In contrast to copper, pure iron does not bond strongly to silicate glass. Also, technical iron contains some carbon which forms bubbles of CO when it is sealed to glass under oxidizing conditions. Both are a major source of problems for the technical enamel coating of steel and make direct seals between iron and glass unsuitable for high vacuum applications. The oxide layer formed on chromium-containing steel can seal vacuum tight to glass and the chromium strongly reacts with carbon. Silver-plated iron was used in early microwave tubes.
Tuilik
The tuilik must seal reasonably at the face and kayak cockpit coaming, and usually at the wrists. This is done using smooth, stretchy, grippy materials. Both laminate fabrics and neoprene will seal, but stretchier neoprene often seals better, so some non-neoprene tuiliks have neoprene rands. Stretchier neoprene with one smooth side may grip and seal better, so even neoprene tuilikusaqs may use a different neoprene for the seals.
Tack cloth
A new type of tack cloth has been developed at the Y-12 National Security Complex, a nuclear weapons plant. Its purpose was to clean up microscopic beryllium particles that posed a health hazard. The inventor, Ron Simandl, also found he could dry-buff the alloy wheels on his car. The stubborn brake and road dirt came right off and left the wheels clean and bright.
Tie (cavity wall)
Due to its materiality of the tie, its corrosion is related to the extent of the exposure at acidic substances. The major factors of the corrosion is these:The cement-based mortar, giving an alkaline environment for cavity wall ties, has been used after World War II. Alkaline environment is beneficial for ties protecting from acid and procrastinating the corrosion process. Before cement-based mortar, lime-based one was used, which does not present an alkaline environment. Therefore, the majority buildings with wall tie corrosion are built before World War II. An alkaline degree gets weaker while exposed at acidic rain over the time.
Saltine cracker
Flat saltine crackers have perforations on their surfaces. During baking, the outer layer of dough hardens first, restricting out-gassing of evolved gasses. The perforations connect the top surface to the bottom surface to prevent the cracker from pillowing as a result of these evolved gasses.
Slater
The zax (also called a sack or sax) is a hand tool for cutting, trimming, and punching nail holes in slate. It consists of a heavy rectangular knife blade with a large point, of square cross section, protruding from the poll (or butt). The blade edge is used to split slate, while the point is used to pierce square holes for mounting the slate on the roof (with square copper nails) or making a series of small holes marking a line where the slate is broken over a slater's iron. The tool is mounted to a laterally offset handle to protect the user's hand from sharp slate chips.
Pitch (resin)
The heating (dry distilling) of wood causes tar and pitch to drip away from the wood and leave behind charcoal. Birchbark is used to make birch-tar, a particularly fine tar. The terms tar and pitch are often used interchangeably. However, pitch is considered more solid, while tar is more liquid. Traditionally, pitch that was used for waterproofing buckets, barrels and small boats was drawn from pine. It is used to make Cutler's resin.
Plug door
A plug door is a door designed to seal itself by taking advantage of pressure difference on its two sides and is typically used on aircraft with cabin pressurization. The higher pressure on one side forces the usually wedge-shaped door into its socket, making a good seal and preventing it from being opened until the pressure is released.
Pine tar
Pine tar has a long history as a wood preservative, as a wood sealant for maritime use, in roofing construction and maintenance, in soaps and in the treatment of carbuncles and skin diseases, such as psoriasis, eczema, and rosacea. One niche application has been in Major League Baseball (MLB) where pine tar is used to enhance the grip of a hitter’s bat. Pine tar is also sometimes used by pitchers to improve their grip on the ball in cold weather.
William Champion (metallurgist)
Because of the American War of Independence, the price of tar greatly increased, which was used at the time as a sealant on ships. On 29 April 1780 an advert appeared in Sarah Farley's Journal offering for sale a process of making English tar, from the estate of the deceased William Champion. Later, a tar works was established within Bristol Harbour.
Oakum
In modern times, the fibrous material used in oakum comes from virgin hemp or jute. In plumbing and marine applications, the fibers are impregnated with tar or a tar-like substance, traditionally pine tar (also called 'Stockholm tar'), an amber-coloured pitch made from pine sap. Tar-like petroleum by-products can also be used for modern oakum. "White oakum" is made from untarred material, and was chiefly used as packing between brick and masonry in pre-war home and building construction, as its breathability allows moisture to continue to wick and transfer.
Tarring (rope)
Some types of rope must be protected from rot by tarring, coating the rope with tar. Hemp rope requires tarring, but Manila, cotton, and synthetics do not. Regular tarring at sea was required when sailing ships used hemp rope."The use of tarred rigging is now of less interest to the seafaring man than formerly because of the rapid and extensive development of steam power. However, tarred rigging is used today on craft of various types to such an extent that the production of tarred goods is an important branch of the cordage industry. The tar best suited for cordage comes from various members of the pine tree family and is obtained by the distillation process, either by using the old kiln or by modern retorts. It is conceded that the kiln-made article is superior for tarred rigging and therefore it is used principally in making first-quality tarred rope. The tar, as it comes from the kiln, is poured into barrels which are shipped to the cordage works. The way this tar is handled and how it is made to penetrate and adhere to the yarn, as is done by the Plymouth Cordage Company, North Plymouth, Mass., may be described as follows:
Taping knife
A taping knife or joint knife is a drywall tool with a wide blade for spreading joint compound, also known as "mud". It can be used to spread mud over nail and screw indents in new drywall applications and is also used when using paper or fiberglass drywall tape to cover seams. Other common uses include patching holes, smoothing wall-coverings and creating specialty artistic wall finishes. Common sizes range from 15cm to 30cm wide (five to 12 inches). Spackle knives are a smaller version, used for patching small holes.
Tar
Mixing tar with linseed oil varnish produces tar paint. Tar paint has a translucent brownish hue and can be used to saturate and tone wood and protect it from weather. Tar paint can also be toned with various pigments, producing translucent colors and preserving the wood texture.
Albertosaurus
William Abler observed in 2001 that "Albertosaurus" tooth serrations resemble a crack in the tooth ending in a round void called an ampulla. Tyrannosaurid teeth were used as holdfasts for pulling flesh off a body, so when a tyrannosaur pulled back on a piece of meat, the tension could cause a purely crack-like serration to spread through the tooth. However, the presence of the ampulla distributed these forces over a larger surface area, and lessened the risk of damage to the tooth under strain. The presence of incisions ending in voids has parallels in human engineering. Guitar makers use incisions ending in voids to, as Abler describes, "impart alternating regions of flexibility and rigidity" to wood they work. The use of a drill to create an "ampulla" of sorts and prevent the propagation of cracks through material is also used to protect aircraft surfaces. Abler demonstrated that a plexiglass bar with incisions called "kerfs" and drilled holes was more than 25% stronger than one with only regularly placed incisions. Unlike tyrannosaurs, ancient predators like phytosaurs and "Dimetrodon" had no adaptations to prevent the crack-like serrations of their teeth from spreading when subjected to the forces of feeding.
Worm, parcel and serve
The tar, or "slush" is a mixture of Stockholm tar, boiled linseed oil, and Japan drier. Many "recipes" for slush exist, but the intent is always to allow a penetrating coat of preservative pine tar that then cures to a harder finish that will not so easily rub off on sails and crew. The term "slush" is also used to describe the grease applied to the masts to lubricate the parrels so that the yards can raise and lower freely.
Crack closure
Crack closure is a phenomenon in fatigue loading, during which the crack remains in a closed position even though some external tensile force is acting on the material. During this process the crack opens only at stress above a particular stress. This is due to factors such as plastic deformation or phase transformation during crack propagation, corrosion of crack surfaces, presence of fluids in the crack, or roughness at cracked surfaces. This provides a longer life for fatigued material than expected, by slowing the crack growth rate.
Tar River
North Carolina was originally a naval stores colony—that is, the blanket of long leaf pines that covered the coastal plain was used by the British Navy for ships' masts and the pine pitch was used to manufacture tar caulking for vessels. The river derives its name from its historic use as a major route for tar-laden barges as they headed to the sea. The city of Tarboro is on the banks of the river. Recent research conducted by East Carolina University, Greenville and Pitt County historians has uncovered documentation noting that before the Civil War, the North Carolina Legislature had appropriated funds to construct dams and locks on the Tar River in an attempt to facilitate almost year round navigation for the farm products and naval stores shipping plus passenger boats which were travelling between Tarboro, through Greenville to Washington.
Among the towns and cities along its course are Louisburg, Rocky Mount, Tarboro, and Greenville. The village of Old Sparta was formerly an important riverport on the Tar, but has declined in the 20th century.
Tubes and primers for ammunition
In most breech loading guns it is essential to stop the erosion of the metal of the vent by preventing the escape of gas through it when the gun is fired. For this purpose the charges in such guns are ignited by "vent-sealing tubes." For muzzle loaded guns and small breech loading guns radially vented, especially those using black powder, the amount of erosion in the vent is not so serious. The charge is fired by ordinary friction tubes, which are blown away by the escape of gas through the vent. In all guns axially vented, vent-sealing tubes, which are not blown out, must be employed to protect the gunners from injury. This 'vent sealing' name remained part of British nomenclature, rather than a clearer name of 'primer' or 'firing' tubes, as used elesewhere.
The common friction tube is a copper tube, packed with powder, having at the upper end a short branch (called a nib piece) at right angles. This branch is filled with friction composition in which a friction bar is embedded. When the friction bar is sharply pulled out, by means of a lanyard, the composition is ignited and sets fire to the powder in the long tube; the flash is conveyed through the vent and ignites the gun charge. For naval purposes, to prevent the sailors from being cut on the face or hurting their feet, tubes of quill instead of copper were used. If friction tubes are employed when cordite or other smokeless powder charges are used, the erosion of the vent is very rapid unless the escape of the gas is prevented; in this case T-headed tubes are used. They are similar in action to the ordinary type, but are fixed to the vent by the head fitting a bayonet joint formed with the vent. The explosion blows a small ball upwards and blocks the coned hole at the top of the tube and so prevents any rush of gas.
Scrim (material)
Scrim is a glass fibre (previously burlap) open mesh tape used to cover the joint in plasterboard/wall board prior to plastering. It prevents a crack appearing in the plaster finish at a later date. The roll of tape may be plain or adhesive coated to facilitate its installation.
Perforation
Screwcaps on glass or plastic bottles are sealed with a ring at the bottom of the cap attached by perforation. Twisting the cap has the effect of rupturing the material between the perforations and indicating that the original seal has been broken.
The edges of film stock are perforated to allow it to be moved precise distances at a time continuously. Similarly, punched cards for use in looms and later in computers input and output devices in some cases were perforated to ensure correct positioning of the card in the device, and to encode information.