Screen Printing Forum

We took this order last week for a company that wanted there font to look like it was glowing. Our art guy made the artwork, and we print it out on single sided polyester film, its clear. We have NuArc Frist Light burn unit. The emulsion we use is compatible as it has worked numerous times since we have opened as a business. However, in order to achieve the halftone like fade we were told to use 200 mesh screens instead of the 110 mesh that we have used on everything else. When we burned this piece of artwork onto the 200 mesh screen, the fade border wouldn't wash out all the way. We can't seem to figure out why, if its just under exposed? The border is a lot lighter than the actually font so that not as much ink will go through to make it have the fade effect. Do we need to burn this for longer than normal. We tried 4.00 minutes, then we tried less time, at 3:40 and they turned out the same. ANY help is very much so appreciated. Thanks!

The nuarc first light unit I googled has flourescent tubes for a light source. If this is what your unit has this is most likely why you can't shoot halftones. You need a single point light source of high intensity for proper exposure. Metal Halide is one of the industry standards for this, there are others. Your time should be around 90 seconds give or take with the proper light source. Using a flourescent system takes too long and opens you up to light undercutting your art to screen, thereby hardening emulsion in areas you need to be open. Mesh is at least a 200 if not higher.

You will also need a good vacuum contact if you are to avoid undercutting.

What size dot did you use? If its too small that could also be the problem.

If you cut down the time and doesn't fix the issue I would check to make sure the artwork is black enough. Also make sure your screen and artwork is flush with the glass of your exposure unit. One easy fix to this is to maybe tape the artwork to the screen.

A good light table is important, but good artwork is much more important. Dot size is key with artwork. When creating fine details, the art (dots, lines, whatever ...) needs to be at least twice the thickness of the mesh's thread thickness. If your dots/lines are the same size or smaller than the mesh thread thickness, the emulsion may wash out, but the dots/lines will often times lie ON the thread, which does not allow ink to pass through the holes in the mesh. Contact your mesh supplier for thread thickness on the mesh count you are using, and then adjust your art to comply with the mesh you are using.