Sandblasting for Glass Artists - Part 2
If you got to this page from Part 1, we are going to assume that you know what the equipment is and how it works. We are also assuming that you have your air compressor connected and working and have abrasive in the hopper. Now we will talk about how you use the sandblaster. For a starting test, take a piece of Black Irid glass and we will practice sandblasting away the irid.
Testing the Equipment
First let's test the equipment by shutting the access door on the blasting cabinet and making sure the dust collector is turned off. Now put your hands in the gloves, grip the gun and point it toward the back of the cabinet. Activate the air gun while watching through the access window. If everything is working right you will get a high-pressure spray of abrasive from the end of the gun. If you put your other gloved hand in front of the gun you will be able to feel it. After about 15 seconds, the inside of then cabinet will get hazy with dust from the abrasive. Now turn ON the dust collector and you should see the visibility improve right away. The purpose of this exercise is to show you what the output of the air gun feels like with abrasive flowing through it and what it looks like inside the cabinet with the dust collector on and with it off. When you are doing real work, you will want to be able to recognize these conditions right away.
Blast Off the Irid
Now we are going to actually blast some glass. Open the access door and take the piece of Black Irid glass and place it in the cabinet. Close the door and turn on the Dust Collector. Hold the Black glass so that you will be working on the Irid side and hold it so that you can easily see the area being sandblasted. With the nozzle of the gun about 3" away from the glass, pull the trigger on the gun. Move the gun slowly from side to side like you were painting a wall. Stop for a moment and look at the glass. If you can see that the Irid is being blasted away, then you can continue testing with the nozzle at different distances from the glass. What you are looking for is that distance that seems to give you the best control over the blasting process.
If there is no Irid being sandblasted off the glass, first check to see that the gun is working and a mix of air and abrasive is coming from the gun. If everything seems to be working properly you will need to start adjusting the air pressure to the gun and/or reducing the distance from the nozzle to the piece of glass.
There are very few absolutes involved in sandblasting. It is mostly getting all the variables working to your satisfaction. These include the distance from the gun to the work, the air pressure, the mixture setting valve (on siphon blasters) and to some extent, the angle at which the abrasion is hitting the glass. Like anything in art, you will develop a technique and a feel for the equipment as you become a better sandblaster. It all comes with patience and practice.
Last Piece of Advice
Maybe I should say the best piece of advice I can give you is to remember that you can always go back to the blaster and take a little more off, but once it's off, you can't put it back on.
Full Nose and Mouth Respirator: Cheap Insurance!
Don't Forget Your Respirator
No matter how careful you are, when you are sandblasting there will be junk in the air. This includes the dust from the abrasive and the small particles of glass you are removing from the glass you are blasting. Always, and I mean always, wear a respirator and keep the filter in your dust collector clean. Silicosis is a very serious lung disease caused by inhalation of crystalline silica dust i.e. glass and abrasives!
Dolphins on Black Irid Glass
Now for a Little Practice
Nothing makes a lesson stick like a little practice. For this exercise we will need a piece of Irid Black glass. If you use Bulseye glass it is the.BE0100F31 which is a plain black with an irid coating, but any irid coated glass will work.
Now go to your local sign maker and ask him for a small piece of vinyl with some letters or a pattern already cut. Tell him you are learning how to sandblast and he will probably give it to you for nothing.If you don't have a sign maker around, your local art supply house will probably sell vinyl images or letters for making signs.
The photo on the right is a piece that I made from a piece of vinyl with an image of dolphins jumping.
Peel off the letters or image and carefully put them in place on the glass. Be careful, the adhesive on the vinyl is very aggressive and it will want to stick in the first place it makes contact. When you have some letters or images on your practice sheet, burnish them down so that they stick well, especially on the corners Now you are ready to sandblast..
Just like you did in the Blast off the Irid paragraph above, start slowly with your nozzle about three inches from the glass. Experiment around until you get the feel of the process. It will eventually become second nature.
Warm Glass the Glass Artists Bible
Safety First! Don't Forget the Respirator
No matter how careful you are, when you are sandblasting there will be junk in the air. This includes the dust from the abrasive and the small particles of glass you are removing from the glass you are blasting. Always, and I mean always wear a respirator and keep the filter in your dust collector. Silicosis is a very serious lung disease caused by inhalation of crystalline silica dust i.e. glass and abrasives!
Keep in mind that contaminates like glass dust and abrasives stay in your lungs once ingested. Silicosis is a cumulative disease and it is eventually terminal. Stretch your budget and get the best respirator you can afford.