Screenprint Answers by Bill Hood
for a natural sun exposure unit only 20 sec(summer) to harden 40 sec winter
There are instructions on using a Compression Exposure Unit at Screenprint Answers (
Screenprint Answers by Bill Hood) but in brief they are:
1. Choose a place indoors, away from direct sunlight to prepare your exposure unit. Place a sheet of foam cut to fit into the screen on a table and cover it with the piece of black cloth.
2. Place the screenprint frame - coated with emulsion that’s dried – over the of the foam and cloth squeegee side down with the bottom of the screen facing upward. Because the emulsion is ‘slow’ you can do this indoors if you act quickly.
3. Place the film positive to be exposed on the emulsion surface “wrong reading” (i.e. backwards) in the center of the screen. Assure that the image is square with the frame by using a T-square or ruler to measure. Once in place, tape it down with the Scotch Brand 810 Magic Tape.
4. Place a clean plate glass (do not use tempered glass as it will inhibit the UV light) over the art, sandwiching the art between the glass and the screenprint mesh.
5. Expose the emulsion to UV energy from above. This unit can be carried out into the sun for 20 seconds on a bright day to expose the emulsion. Or you can use a single point light source situated above the unit. The distance from lamp to screen should be equal to the diagonal of the frame.
6. You can use the inexpensive Step Wedge Exposure Calculator (
Products and Services for Screenprinters) for determining your exposure times.
will make sharper images and finer lines
» Screen Print the DIY way
If you must expose your screens at night I would suggest that you use a photoflood bulb or at least a quartz halogen work light bulb to lower your exposures.
I just made a home made exposure unit from stuff i bought around town. My exposure time is 6 min. I used 4 40 watt black light bulbs (Not black light Blue bulbs, like you see at some stoner's house.) These bulbs look just like regular fluorescent, but do not have the 'visible light' filterers that make black lights that deep violet color. I found them at a local lighting supply distributor. They cost about $11 each. You can find a fixture that holds 4 40 watt bulbs and includes the ballasts and light diffuser screen for $40 at Lowe's. Then I just built a box and stand, and put a piece of glass over it. You can get a piece of glass cut at any glass / window place. the dimensions i needed were 23 3/4" x 37 3/4" (the same as the outer dimensions of the fixture i bought). Then I just cut a cheap extension cord and wired it up with a light switch. It works great.
eg if only using tin foil with 200w normal light..
200w 40 min
500w 10 min to7 min
150w 70 min
i copied those things from that page let us know how it went... im just wondering... how thick do u set the emulsion do u cake it or just barely spread it? could u give me like a thickness in millimetres?
Plans for home made units 
So once Im finished and draw up the plans I'll take some pics and post them here. I hope others will do the same.
