I found a great tutorial on Instructables for “true DIY guide to screen printing” that included instructions on making photo emulsion using a chemical called Potassium Dichromate (which I found at Kama Pigment in Montreal).
WARNING: Potassium Dichromate can kill you ‘n shit.
This is the cheapest photo emulsion you will ever find… and it works for fine detail artwork and on any screen mesh. But only with water based inks.
**this post gets so many visitors! it’s crazy!!**
Definitely look at the tutorial on Instructables first, that guy offers lots of important information!! Read the comments there too…
This is my “converted to baking measurements” recipe. If you need help with conversions from oz to ml to cups, I use this conversion site.
1/2 cup of PVA white craft or carpenters glue (water soluble)
1/2 teaspoon of potassium dichromate
3 teaspoons of warm water
White craft or carpenters PVA glue, I buy it at the dollar store or craft store. Any cheap water soluble glue will work. Carpenters glue has a slightly better bond, but it’s a little more expensive. 120ml of glue makes just enough to cover three medium/large size screens.
Potassium Dichromate can be purchased at speciality arts stores that carry supplies for wood staining, leather tanning, custom pigment paints, etc. I found mine at Kama Pigments in Montreal.
First of all, work in a dimly lit room (obviously not totally dark or you can’t see what you are doing, just don’t use an overhead light and not in direct sunlight you should be fine)
Wear gloves… try not to get this stuff on you, it is toxic as hell.
In a small plastic or glass container, put 3 teaspoons of warm water.
Add 1/2 teaspoon of Potassium Dichromate and stir until dissolved. (do not use these measuring utensils or containers for food or anything else afterwards!)
The Potassium Dichromate is sensitive to light only AFTER you add water, but I do keep mine in a airtight container that I covered with duct tape, just to keep it at max potency. The store where I bought it though just has it in clear plastic bags on a shelf. I bought a 1/4 pound bag of it for about 8 dollars over 5 years ago and it still hasn’t lost any strength that I can notice (and I’ve got enough left to last another few years!)
Add 1/2 cup of glue and stir well until consistent and no lumps etc…
Again, do this in a dimly lit room (no overhead light or sunlight)
Spread thin and even on your prepared screen with a squeegee, as you would regular photo emulsion, and allow to dry. The Instructable link has info for preparing screens and squeegees etc, and there is lots of other info out there for that so I won’t repeat it.
Depends on your bulb, distance, size of the screen, image opaqueness, etc. This is a trial and error process you will have to experiment with your timings to get it right.
In the photo below I think I was using a 100 w bulb, and it’s definitely too close. Since then I’ve got a 250 w bulb suspended at least 2 feet above the screen and expose for about 12-14 minutes.
OMG I made a video tutorial! Enjoy!
Cheerz and happy printing!