Often times people have problems with their photoresist stencil blowing off while sandblasting. This is a fairly common problem that happens. It doesn’t seem to happen as much with a regular vinyl stencil but does every once in awhile.
A fellow glass sandblaster, named John, emailed me about this problem, and here is my response with a bullet list of rules and actions to consider.
- Use a Finer Abrasive Grit: There could be a few things to consider, but the one that comes to mind is that the grit being used is too large. I personally use about 150 or 180 grit. I recommend that you don’t use anything larger in size than 100 grit (but my grit standards are set at least 120 and finer). Sometimes they don’t emphasis this enough, but the finer the grit is, the less blow off problems you will usually have, and the thinner the vinyl stencil can be. I talked about that in the ebook a little bit also. A lot of times, I will actually do some sandcarving (www.glassetchingsecrets.com/glasssandblasting.html) with a 3 mil vinyl with a fine grit. Works fairly nice. By the way, here are some more steps to follow for glass sandcarving.
- Ensure a Clean Surface: Another problem could be due to having a unclean surface. Even if the glass appears to look very clean, it still has oils from people’s hands. You can wipe the glass down with a cleaner such as rubbing alcohol.
- Dry Out the Resist, but not too Dry: Make sure the photoresist is dry, but not bone dry. I use the type that doesn’t require an application of adhesive. It’s most tacky when it is almost dry. If the photoresist still has moisture shown on the surface, then the it won’t adhere very well.
- Lower the Air Pressure: A fourth rule, is to make sure the sandblasting pressure isn’t set at too high of a pressure. The company will usually have a recommended and maximum pressure that can be used for each specific resist thickness. It will also explain the first rule I stated. If a larger grit is used, you may have to back off the pressure also.
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