I have gotten many emails about the lamps used in my home built exposure unit. I should probably write up a FAQ some day. Anyways, the lamps are a special unfiltered black light. The designation is F20T12-BL. These lamps don’t block UV rays like the ones you buy in the store. The emulsion you coat your screens with is sensitive to UV. When the emulsion is exposed to UV it will cure or harden. The art work blocks the UV and that area will wash out. That is the reason you need a good black art image in order to block the UV entirely.
The black lights you buy at the Walmart, filter the UV out. The UV is what we need to expose our screens so you you would end up with your image washing out.
I have heard of people using plant grow lights sold in the garden department. They will have a lower uv level and I don’t know how they will work.
So, to get the good lamps, you need to goto the local lighting supply or check out: http://www.1000bulbs.com/F20T12/1246/