Sand Blasting Glass

By makerfairemilwaukee, Jul 25, 2014

One of the many hobbies I have acquired in the last two years since becoming a member of Milwaukee Maker Space is the craft of taking a simple piece of glass and creating an etched piece of art with the application of garnet and sand mixture.

Sounds complicated, and it can be, but amazingly not for the reasons most people think.

First: I need to select the glass I want to sand blast. Normally I make these items as gifts, so I have to keep the person in mind. The images of the glasses in this blog are going to a charity event and will be silent auctioned off to raise money for a good cause.  Because this event is a wine tasting and silent auction, the glasses I selected and the theme of the sand blasting was all about wine.

I typically go to Goodwill first and foremost to get my glasses. They almost always have what I want, at a good price, and it helps the community. I look for glasses that don’t have a lot of jagged edges or ripples, and aren’t too curvy. Pilsners and Wine Glasses can be a bit too curvy and I usually avoid them (I made an exception for this event). I will get to the reason for the curves in the third step.

I clean my glasses and make sure they are dry before going to the next phase.

Second: I sit down with my computer and I open up a program called Silhouette Studio. This program interacts with the Silhouette Vinyl cutter, which is used in the sand blasting process.

I try to find and use higher resolution images, preferably two-tone with as few jagged edges and itty-bitty details in the image as possible. Importing the image into the program I then use a tool called “Trace” to literally trace the outer and inner edges of the image.

If there are too many details, especially tiny ones, I may need to do a lot of digital clean up. I had one project that I drew, scanned, brought into Silhouette Studio and had to spend about four hours cleaning it up so that it was ready for cutting into vinyl. Hand-drawn and then scanned in tends to have many small jagged lines that require that kind of attention to detail in order for the cut to be clean.  Simple designs are always the best, and thin lines are not always an issue. I’ve done Celtic knots for sand blasting into glass with little issue.

I make sure, using the program’s grid, that the size of my project will not be too small or too large for the glass. Size adjusted, image cleaned up, vinyl on the cutting mat (loaded to go), and I am all set.

Using the Silhouette program to interact with our vinyl cutter, I will cut the design out of vinyl and peel it away from the special cutting mat to transfer onto the glass.

Three: This is the first of two tedious steps, I won’t lie. It takes a steady, careful hand and an eye for details (like where things need to rest) to get your glass ready. This is also where the lack of too many curves becomes critical unless you make adjustments to the vinyl. So…vinyl is flat. Even a glass that is round is not an issue, it’s when the glass starts to curve in and out that things become a hassle. The vinyl wants to lie flat, but the curves of something like a wine glass do not allow it do to so.

This means you have wrinkles in your vinyl. Letters will arch up or down slightly on the curved areas, and you may have to apply your vinyl in small pieces rather than in a single large design. This can also lead to some reconfiguration or redesigning that you may not have planned for. Two of the wine glasses had to be redesigned before I could put them on.

The other thing to think about when putting on the vinyl design is if you want your design to be the cloudy area (where the sand touches the glass and etches it), or if you want it to be clear and everything else to be opaque. Anything the vinyl is not touching will be opaque, while the places the tape or vinyl is touching will be clear at the end of the process.

For these glasses I wanted my designs to be opaque and the rest of the glasses to be clear. This meant that after I put the designs on, I had to cover everything else that I didn’t want sand blasted on the glass with the left over vinyl that I had on hand. I did use a little bit of tape as well.

Four: Design and tape on and I am ready to sand blast. The sand blaster uses a fine garnet and sand mixture that is pinkish in hue. One glass at a time I put it into the sand blasting cabinet, turn the machine one, and with a special air gun, I spray the glass with the mixture. The sand-garnet mixture is pressurized by 120 psi of air (PSI = pounds per inch). I need to hold the glass about 1 foot away in the sand blasting cabinet, if not 2 feet) to ensure that the air-sand coming out does not rip the vinyl and tape. I usually have some ripping and it is something I’ve had to accept will happen.

Five: The second tedious step is removing the tape and vinyl on the glass. One by one I unwrap my work to see the finished product and inspect if there were any accidental marks from the sand blasting caused by me missing a spot when covering it or just ripping the vinyl. If there are mistakes I need to decide if they are ones I am ok with. I have had to redo more than one piece because of the mistakes that happen. This is part of the making process though.

I usually use both my fingernails and an exacto blade to remove all the tape and vinyl. It can take a long time, but once I am done I have lovely sand blasted glasses that I can give to friends, family or the occasional charity event.