Silk Screen Printing Tip

Screen Printing Emulsion & Sensitizer Mixing

These instructions are for mixing a sensitizer to a photo sensitive emulsion used in screen printing. These emulsions are known as Dual Cure or Diazo. Photo-polymer emulsions have the sensitizer pre-mixed into the emulsion. There are 2 types of sensitizer used in the screen printing world, powder and liquid. The powder sensitizer is harder to dissolve, so you need to spend more time shaking the bottle.

screen printing prep

Before you start opening containers you need to have:

It is normal for the sensitizer to change the emulsions color after mixing.

  1. A spatula for stirring
  2. Towels for cleanup
  3. An area under low light conditions. Usually a yellow or red light.
  4. Access to tap water
  5. A table covered with news paper for fast clean up


Note: Always stir the emulsion before it is used. If it is not mixed the solids go to the bottom, and the sensitizer floats to the top. The emulsion on top with all of the sensitizer exposes great, but when you get half way down the container, your emulsion does not expose properly.

Sensitized emulsion Storage Keep sensitized emulsion in a cool dark place like the refrigerator.

Instructions to mix the sensitizer with the sensitizer.

Optional step-you can if you wish, mix the sensitizer with the emulsion

  1. Open the emulsion container and the sensitizer bottle.
  2. Fill the sensitizer about 1/2 full with tap water
  3. Replace the cap and shake well.
  4. Pour contents from the sensitizer bottle into the emulsion container
  5. Refill sensitizer bottle 1/2 way full with tap water
  6. Replace the cap and shake well
  7. Pour the contents from the sensitizer bottle into the emulsion container
  8. Using your spatula, mix the sensitizer and emulsion together, until you are back to one solid color. Be sure to scrape the sides and the bottom.
  9. Place the lid back onto the emulsion container.
  10. Let sit for 1-2 hours (See “Note” below).
  11. Throw the empty sensitizer bottle into the trash