Is vacuum important for exposing screen printing frames?
It is very important, but especially so for fine detail and half tones. If you want the best reproduction, you need to have the film solidly against the emulsion on the screen fabric. Failure to do so will reduce image sharpness as light bleeds under opaque portions of the film. The result is not unlike the difference between the sharp edges of a laser beam and the fuzzy edges of the beam from a flashlight. Creating a vacuum allows atmospheric pressure to draw the blanket and glass together under more pressure than can be achieved in any other practical way. The vacuum ensures that the film is held against the emulsion under uniform pressure, assuring intimate contact between the two. For the very best results, combine a high-quality vacuum frame with an equally good point light source. All NuArc exposure systems rely on vacuum drawdown to ensure the closest film-to-screen contact and the sharpest images.
