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I also use intermediate vinyl for just light etching and cut the masks on the plotter. For deep carving I use different rubber resists...thicker (3M) for hand cutting and when it calls for deep cuts and some of the Hartco resist made for plotters.
Be sure and cover every sqare inch of your glass, including the back...especially on mirrors. It is so easy to get a little nick in the silver.
When handcutting on the mirrored side, all cuts must be precise....one overcut and it's shot.
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For anyone who would be interested: Hartco manufactures a 10 mil product which was designed for blasting on glass.
I would be happy to send out a sample of this or any of our other resists to anyone who asks. e-mail me or call Hartco at 1-800-543-1340. x-106 If you haven't tried it in a few years - then you haven't tried it.
Also - One of my associates will be presenting at the Sandcastles meet in FL. If you are planning on attending, make sure you keep him on his toes
posted
I blast the back, thru the mirror coating, and use high tac rubber stencil. I'm looking forward to trying the 10 mil from harco at the Sandcastle meet.
The reason that I use high tac is that when reverse blasting mirror, the edges of the design tend to get microscopic chips which are pulled off of the mirror back when the stencil is removed. So, what I began doing is actually leaving the stencil ON the mirror permanantly. This protects the mirror surface, plus avoids pulling off those tiny specks of mirror around the design.
As mentioned above, the front of the mirror must also be protected. I use the same paper premask that is used for vinyl lettering transfer. It has enough tack to stay put on the glass, while being easy to apply and inexpensive. Leave this protection on the glass until after blasting is complete and any abrasive residue has been cleaned off.
Oh...and Randy....don't forget to do all your layout backwards. I only forgot this vital step once....I don't think anybody has ever done it wrong more than once. hahahaha
One little trick you may want to try is airbrushing one shot pearlescent paint to the back of your blasted design. The colors look great when backlighted!
Have fun!
[ April 02, 2003, 07:55 PM: Message edited by: Don Coplen ]
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Don, I like your idea of leaving the mask on the back of the mirror but had been leery of doing so for fear that eventually the adhesives would harm the coating and affect the silver. I had a glass guy tell me that many adhesives and chemicals will ruin mirrors. Have you ever seen any long term problems when etching and backpainting mirror?
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Mark...no, haven't seen any adverse effects. I've only used this on factory silvered mirror, which has that hard, baked backing coat. So, have no worries about the silver below it. In time, the rubber will get brittle, but doesn't/hasn't cracked...so continues to fulfill its purpose.
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I do a lot of glass and mirror blasting and i like paint mask for a simple etch. It sticks good and comes off easy. Just don't use too high a pressure and keep moving so as not to burn the mask. I also prefer blasting the back of mirrors vs. the front. When blasting on the front, the reflection of the etch will blend in with the etch and the detail disappears when viewing at an angle. And as mentioned before, don't forget to mirror the stencil if blasting on the back.
For depth, then use the sandblast resists.
Real Mercier
-------------------- Real Mercier West Springfield, MA Posts: 29 | From: West Springfield, MA USA | Registered: Feb 1999
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posted
Hi Randy For Just blasting Pete would mask off the glass on the back with what we call Flexon White paint mask -peels off easy, plotter cuttable or hand cuttable, is kind of brittle though. He has also used Yellow paint mask in the same way as above it has more flex and is a little nicer to use, both of the above have a low tack for easy removal. If Pete was going to do stage blasting he would and has used Hartco 310 plotter or hand cuttable, great stuff. We find blasting with Aluminum oxide we get very smooth clarity All product available through us.
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