I tryed exposing for 10 minutes and my design doesn’t wash out. I used Emulsion for beginners. And I used a uv light and stand from Amazon.

  • This can not be answered, theres no info on emulsion used nor what the light is like (wavelength, spread, light producing method; 20w lightbulb is way different from a 20w led, would be better to know lumens on surface). That said there are people who feel this question does not fit here.
    – joojaa
    Jun 14, 2023 at 15:38
  • 1
    Does this answer your question? How do I determine exposure time for a silkscreen?
    – Tetsujin
    Jun 14, 2023 at 15:47

1 Answer 1


The only way to know is that you make a controlled test. I am assuming the emulsion actually works.

  1. The first step would be reading the instructions for the product.

  2. But on your specific setup you can do a test strip.

  • Cover for example 80% of the area of the emulsion (and design) with thick flat cardboard (It is better if it is painted black on the side of contact) and put some weight on it. 20% will be exposed.

  • Expose X amount of time. Let's say 5 mins. But as you already have tested 10 mins, start with that time.

  • After time X, uncover 20% more. The first strip will be exposed 2X.

  • You can now test 1X to 5X time and see which exposure works best for your combination of exposure, light intensity, light distance, temperature, and other variables.

  • The test strip will tell you not only which time is enough to harden the emulsion, but also if the design gets too hard to wash because the borders of the design, especially on thin lines got also burned.

I don't know what is the power of the lights you have, or quality, etc.

If 25-30 mins is not enough, I would make a strip test on sunlight, to see if the emulsion actually works, then I can discard 1 variable. Probably you can do the sun strip test first. The base time X can be different depending on the product.

A variation on the times of the first test can be using squares. So the first strip will be exposed double the time incrementally. For example:

In minutes: 1, 2, 4, 8, 16

So the exposure will be 31, 15, 7, 3, 1.

Then you can have a rough idea and refine it later with a linear change. This is especially useful for example the sun test because some products could be fast enough to be ready on the first strips.

  • I added this answer to the other question.
    – Rafael
    Jun 14, 2023 at 17:01

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