Exposing the PhotoMask™ Click for more info

Avoid direct sunlight contact with unprocessed PhotoMask™. Normal inside lighting is O.K. to work under but don't leave unexposed film out for too long.

Using black printed artwork on Vellum paper or PhotoPositive Film, place the artwork emulsion side onto the emulsion side of the unexposed PhotoMask™. Your light source must go through the artwork and then onto the emulsion side of the PhotoMask™.

With a Letralite exposure unit expose 3 - 6mil PhotoMask for 30 seconds. You won't see any image until you start to wash out.

Washing out PhotoMask™ Click for more info

You must have a good quality trigger jet water spray head to wash out the image efficiently. Normal hose sprayers will not give consistently good results. Normal tap water is used to wash out PhotoMask. Warm water is the fastest but cold water will work well.

Attach the exposed PhotoMask to a clipboard or other flat surface with the emulsion side up. Spray the PhotoMask moving slowly, constantly across the image keeping 4" to 6" away from the surface. The image should start to washout instantly. If this does not happen you have over-exposed the PhotoMask to light.

Drying the washed out resist Click for more info

Use a blotting towel to remove excess water. Place the resist into a drying cabinet such as ProBlast's film dryer and dry the resist. This will take about 8 minutes. Alternatively hang up and allow to air dry for approximately 1 hour or Microwave the resist on low heat for about 10 minutes.

The resist must be completely dry before applying to the item to be blasted. Damp resist will not adhere properly.

Adhesive application

When your sheet of resist is dry apply RZ-2 adhesive. This can be done in two ways. Use a gravity fed spray gun to spray the resist's emulsion surface with adhesive or using a sponge brush apply a thin layer of adhesive directly to the item to be blasted. Make sure you get a thin even layer of adhesive onto the surface. Too much adhesive or uneven coverage will result in difficulties when blasting.
With either method allow the adhesive to dry to a clear tacking finish before applying the resist to the blasting surface.

Applying the resist

Lay the resist carefully and squarely onto the item to be blasted. Start at one end of the resist and work your way to the other end. Try to avoid bubbles in the resist. Use a plastic burnish to rub down the resist onto the surface. When you are satisfied that the resist is applied properly flick off the top clear cover sheet. Tape up the area around the resist or cover with a rubber mask.

Blasting

Pressure Pot systems should be set to 20-30psi and Siphon systems should be set at about 80psi. Holding your nozzle 4"-6" away blast in a slow uniformed moving motion making sure you are blasting squarely onto the surface. Do not spray at an angle, this may cause the abrasive to get under the resist and ruin the job.
Blast until you get a nice even depth.

Cleaning up Click for more info

Once you have finished blasting clean off the resist by either soaking it in warm soapy water or peeling off the resist with your fingers.

Voila