Author: Bob Pickard
Published: May 16, 2002
Revised: April 04, 2005
Many types of materials can be used as resist, the most common ones being vinyl, photo, masking tape and rubber. Most of us have used these resist when doing silhouette, shadow, multilayer, and carving. Some of the less used resist are Elmer Glue, spray adhesive, lace window screen, and steel mash to produce special effect on the glass. Most of these resist are used for surface or near surface blasting because they will not take heavy blasting or can't be glued to the glass. Another disadvantage of these special effects resist, they are preprogrammed, that is, you cannot change the design. The exception to this is the Elmer glue.
What if you could have a resist that was completely programmable, a resist you could program into any design you wanted and create any effect on glass your mind could conceive? There is a resist that will let you do just that and it is latex acrylic silicon adhesive. With this resist I have been able to produce clouds, rain, water falls, breaking waves on the ocean, tree bark, leaves, grass, wheat, sheep wool, and animal hair to name a few. There has not been any special effect I can't blast on glass using this resist.
The resist can be used full strength, as it comes from the tube or thinned using water. When you finished blasting the resist, you can rubbed it off using warm water. If you are not happy with the blasting results the first time you can apply it again and blast it.
I apply the resist with two different methods. One way is to apply a thin layer of silicon using your finger as an applicator. Once the resist is on the glass, I use different applicator to create my design. Foam rubber is great to create smooth wool and coarse texture foam will produce a heavy wool effect. Cut the foam into a 1/4-inch square about 1-1/2 inch long and dab the resist with the end of the foam to create the effect.
Another way to apply the resist is to put the silicon on a piece of paper and then dab the foam applicator into the silicon and then dab it onto the glass. I found this method gives me a better result for wool.
The design you see in the resist is a negative of what will be blasted on the glass. The blank area and thinner resist will be the design you get when you finish blasting. It was hard for me to get used to see the blast and thinner areas as being the design that I wanted to produce on the glass.
You will be amazed at the many effects you can get just by using the tip of your finger. Things like waterfall and clouds are easy to produce. Other types of applicators are steel wool, end of wire nuts, plastic soda bottle caps, wire brush, piece of carpet, wood, plastic wrap, rubber stamps, and the list goes on.
After the silicon is applied and formed into the effect you want, it's time for drying the resist. You could let time dry it for you or you can speed the drying up with the use of a hair dryer. You must do all your design work with in 3 minutes because a film will form on the surface of the silicon and it will be hard to work. For this reason you should apply the silicon only on a small area about 6 square inches. When the silicon is dry it will become clear and the thin areas will dry faster than the thicker areas.
If the resist is still white when you start to blast, it will turn loose from
the glass and not give you the results you want.
When the silicon resist is dry, it is time to blast. The silicon has a high resistance to the blasting media and requires about 60 psi to produce the effect you want. I use a 3/32 tip and hold it about 3 inches from the glass while blasting. By controlling your blasting, you can control the depth into the glass. You will notice the thinner resist will blast away first and the heaviest resist will be the last to go. If it is too thick you will not blast through it.
I hope the silicon resist opens up a new world in sandcarving for you and raises the quality of your sand carving to greater heights.