hello all, i am building my own exposure unit based on Screen Printing Exposure Unit
I didnt do it EXACTLY like that, as i dont think id use the tracing lights etc, BUT i cant tell from his vid and im wondering if any of you know, does the bottom, under the lights need to be sealed (BOXED IN) as you can see from mine, its open right now, also has anybody built a similar exposure unit to this? how long should i be letting my screens burn, these are 20wt black lights...here is what ive got so far...
what else do i need to burn my screens? do i cover with glass or black paper or what? any help is greatly appreciated.
Unfiltered black lights are not black, they look like ordinary fluorescents until they power up, same thing they use in tanning beds.
I would seal the back and paint the inside white to increase the amount of UV reaching your screens.
You need a piece of foam or a board covered in black material to set on top and weight to insure good contact of your film to your screen to reduce undercutting of the stencil
awesome! thanks, ill order those now, and ill seal up the bottom.
i just have a couple more questions, the foam or wood covered in black, can you explain that a little more ? what exactly should i use? wood or foam? ive heard people set glass ontop as well?
my other question is about emulsion, using the set up i have, what would be the most effective emulsion to use? what are my approximate exposing times? like 10 minutes or shorter like 2-5?
I have no experience with 1000 bulbs so I can't vouch for them, was the first link that came up when I googled the bulbs.
Basically you need something smooth & flat to fit inside the frame to push the screen into contact with your film, a piece of laminate covered particle board would also work. The heavier the better, stack some books or other weights on it to help.
You want to cover it in black fabric to keep any stray UV from bouncing around and exposing other parts of your stencil.
All emulsions expose @ different rates, pick one and get a stoffer strip and do an exposure test to determine the optimum exposure time
topbulb.com has them. I put foil around the inside of mine and made a vacumm lid. Every emulsion burns different so you will have to figure that out on your own. I have plate glass on mine and make sure the glass doesnt have uv in it. People never believe me on here but I can burn a screen in 30 seconds with those lights and Saatti Textile Pv emulsion from one stroke inks.. That stuff has a year shelf life and no mixing. Good halftones too.
Here is a link to my box build:
[media]http://www.wheelerdecals.com/ExposureLight.pdf[/media]
[media]http://www.wheelerdecals.com/ExposureLightback.pdf[/media]
Building a lightbox saves so much time, I went from a halogent work light with a 12 minute exposure time to a florecent box, I think its 8 4 footers in their and I can now burn a screen in 40 seconds.
I have 6 tubes in mine, enclosed box, 1/4 " unfiltered glass. use a piece of HEAVY black cloth folded in two then a block of foam cut to fit INSIDE the screen ( I think it helps with wight distribution.). On top of the foam a piece of plywood then the weights. I use pc-701 and have had no problems with halftones or spot screens.
The foam helps press the mesh down to the stencil evenly. P701 is the ulsion we use The weightsare nothing special, we use gallon jugs of water
4 of them.
I dont use foam, I use a big piece of card board and 4 bricks or big books. I love my unit. I coat it air dry it in my screen rack with the belp of a box fan burn it, washout then dry the screen on my conveyor. Total time from coati.g to ready to pri.t is around 20 minutes.
The S.E.X emulsion is great. I expose halftones fine detail without issue. I use a blacklight table. Paul what mesh is your 3.5 exposure time. I might do some experimenting with a single point and even build a table.
Sben, 110 to 200 mesh. Mainly 156 mesh. Maybe 200 once a week. I try to stay away from 110, but use it every now and than.
I don't use a table. Have a PVC setup similar to Ryonet and other suppliers. There's is 16" and 1/8" glass. Mine is 12" and 1/4" Low E Glass.
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