Post-exposure is often widely believed to compensate for an underexposed stencil. Some emulsion manufacturers claim it offers no benefit, while others say it can marginally improve durability. All agree that it does nothing to reverse the dot gain or loss brought about by underexposure. They also agree that benefits would only be seen on slightly underexposed screens, and the first line of attack should be to expose screens correctly. And that, they say, frequently means changing one or more of the variables in the exposure process.
Stencils are sensitive to actinic light, a blend of UV and blue-violet waves of the spectrum.
A good stencil needs to be cured right down to its point of contact with the mesh if it is to withstand any kind of abuse on press. Thorough stencil cure should be considered just as important as thorough ink cure. Lamp intensity The quality as well as quantity of light is important for a fast, efficient cure. Incandescent and flood lights don't emit enough of these wavelengths to be considered serious production tools. With few exceptions, all stencil materials can be used with exposure units, but you may see differences in time and image quality, depending on the light emitted.