Okay, so you’ve wasted hours of work and expensive emulsion trying to burn off a screen and still end up with a shitty screen that doesn’t wash out or is a slimy mess that washes out all the way. So ask how long do I expose my screens? This is the question that most new people ask themselves when they get into screen printing. The answer is a company, that depends.
It depends on the brand and type of emulsion, the number of emulsion layers on the screen, the time of day, the lunar cycle, and many other factors. The best way to find out the best exposure time is to use a test strip or exposure tool. The exposure tools are printed on clear plastic and have different gradients from light to dark.
These strips can cost upwards of $ 30, but there is a cheaper way. Take a piece of art that you have printed on acetate and cover one part with construction paper. Expose the screen for one minute. Then move the construction paper to expose the next part of the art image and expose it again for another minute.
Do this 5 times and you end up with a screen with 5 different exposure times, from one minute to five minutes. Wash the screen and the area that washes best is its exposure time. Whenever you have trouble with exposure, take this test and recalculate your times. You will definitely want to do this when you change emulsion type / make or go to another mesh count screen etc.
So start using test strips today and get great screens that make screen printing easy and fun.