Use cool to luke warm water. Hot water can cause the stencil to swell and retain water making it harder to dry and decreasing the longevity of the stencil.
Water Pressure, Spray Pattern and Distance
For most novice screen printers using a garden hose is the best technique for washout. The majority of screen printers typically under expose their screens unknowingly. Using less pressure can help to maintain the stencil even if it is slightly under exposed.
When using garden hose pressure, select a nozzle that has a strong fan spray pattern and don't be afraid to get close to the screen.
Higher water pressure is actually more effective at removing the unexposed emulsion than low pressure. With a properly exposed stencil, the increased pressure does a better job clearing out the emulsion in unexposed areas. High-quality emulsions can easily withstand pressure if exposed properly. Using a pressure washer for stencil development you get better edge definition & halftones.
- Stick with pressure washers of 2000 psi
- Stay about of 12 inches to15 inches from the wand to the stencil surface. The higher the pressure used the more you should back up in distance. Moving in too close will be degrade the stencil during development.
- Use a fan spray, not a narrow stream.
- Always start the spray off the stencil area and work your way into the image area.
Equal time spent on both sides of the screen during washout can effectively clear out the image areas better on direct emulsion.
For capillary film, it is best to washout on the substrate side as the squeegee side is more sensitive to pressure.
The entire stencil should be washed evenly. Uneven washout of the non-image areas will leave unexposed emulsion on the screen, which can cause scumming. A good washout procedure should include even and consistent motion across the entire stencil surface.
Do not washout or soak your stencils. The excessive exposure to water can breakdown the stencil by causing it to swell. This excess can even cause a properly exposed screen to begin to degrade. If your washout process is excessively hard this can be an indication of over-exposure.