A range of etch resists exist which, in conjunction with a suitable UV mask, permit the transfer of a PCB pattern to a copper clad board.
Resists can be either positive or negative depending on whether the resist is destroyed or cured by the UV light, respectively. Positive resists are the most common as the positive UV masks are simpler to produce than negatives.
These films have peak sensitivity to UV light at 3650 Å. UVA (Solaria) and Black light lamps are therefore suitable sources. Read the manufactures data sheets if unsure and experiment with sample material to obtain suitable exposure times.
Erasing EPROMs requires exposure to UV light of wavelength 2537 Å (possibly shorter) through a (usually quartz) window on the device. Sufficient energy must be delivered to the EPROM to erase it fully.
The manufacturers data sheets will specify an exposure time for a given flux density (in Watts per square centimetre). If the flux density is higher then the exposure time can be reduced commensurately; i.e. the product of time (in seconds) and flux density should be constant.
Details on how to build a cheap EPROM eraser are at the following URL; http://www.paranoia.com/%7Efilipg/HTML/FAQ/BODY/F_uv_EPROM.html