Carpentry is another profession learned through apprenticeship. An apprenticeship is a system of training a new generation of practitioners of a trade or profession with on-the-job training and often some accompanying study (classroom work and reading). Apprenticeship also enables practitioners to gain a license to practice in a regulated profession.
A black light is a source of electromagnetic radiation that emits near-ultraviolet light, usually in the 350-375 nanometer wavelength range. This range is just slightly below the 400nm that human eyes can detect. When this light is reflected off certain materials, it looses energy and its wavelength expands to over 400nm. The reflected light is then visible to human eyes, and the illuminated objects appear to glow.
Black absorbs all of the wavelengths of light, converting them into heat. At the same time, black does not reflect any of the other colors. Black absorbs every wavelength of light without reflecting any back. This is what makes it appear as black, which is the absence of color being visible. This also means that black absorbs the most heat of all, since light is connected to heat. Black contains all of the wavelengths of light within it. Conversely, white reflects all wavelengths of light, and it absorbs the least light and heat.