It is frequently desirable to seal the joint between two walls or surfaces of an enclosure so as to prevent or resist penetration of the joint by fluids such as water. There are different types of exposure to fluids. In certain situations, the joint immersed in the fluid and there is positive pressure forcing the fluid against the joint to breach it. In other circumstances, the fluid is a liquid which merely wets the exterior of the walls involved and there is no positive pressure forcing the liquid into the joint. In this latter case, the presence of the liquid may result from condensation or rain.
This need to seal a joint to prevent its penetration by some fluid arises very frequently in the packaging of electronic equipment for use in a damp or wet environment for example. The problem has of course been solved successfully by the use of O-ring gaskets such as found in water resistant watch cases. It is also well known to use liquid caulks and sealants or flat gaskets to form this seal. But one can see that each of these solutions requires an additional element or material in order to effect the seal. This increases the cost and complexity of the assembly process. In addition, since the seal is formed within the joint itself, improper seating of the gasket can occur on occasion without any way available to detect this condition.