i went to a hardware store and bought a $3 USD ($3.38 CAD) standard socket clamp lamp, and a 300W bulb. i burn my screens at about 18 in (46 cm) for about 15 minutes (15 min.)
i also put a piece of black cloth behind my screen to prevent light from shining through and reflecting back and exposing my screen from behind.
it's a cheap and easy set up, and it's never failed me.

A

Mary,

I'm using just regular old 20W fluorescent bulbs, and they work just fine. From what I can gather from extensive googling this subject, basically anything light source will work (depending on your emulsion), you just have to experiment to determine the best exposure time and distance of light from the screen. If nothing's happening to your screen after 30 minutes of exposure with your current set-up, I would recommend taking the following troubleshooting steps:

1. Check to see if emulsion is mixed properly, and is of the appropriate type to use with your light source (some require a special admixture, some require a particular type of light, etc.).

2. Check to see if the emulsion you're using is still good (this seems obvious, but sometimes emulsion accidentally gets exposed or goes bad). Also, make sure your screen is nicely coated and left in the dark before actually exposing it to your light source.

3. Check to see if the emulsion you bought came with a guide for exposure distance/time. I know Speedball has a guide, so whoever made yours might have one too.

Also, here are a few links I found to be helpful:

This is my personal favorite--it's an absolute screenprinting bible:
www.reddingk.com/img/reproguide.pdf

Here's one on exposure units and light sources:
stitches.com/mag/apparel...t/index.html

And if you want to get REALLY obsessive-compulsive about it, you can make a chart based on this one to document your process exactly to determine which steps work and which don't:
www.sgia.org/pdf_server.cfm

And this one is the other discussion about my own experiments and other people's advice:
diyscreenprint.tribe.net/threa...ba2590

Here's one to my blog where I'm keeping a running journal of how my light table is coming along--there's also a test positive there that you can print out and use as a guide for proper exposure times, scroll down a bit to find it:
volitionalerrors.blogspot.com

Phew. What a mouthful.