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Sand Blasting

When you etch the glass by sandblasting you are actually creating rough, obscure areas to contrast with the smooth, clear areas of the glass.This is accomplished by mixing abrasive grit with air under pressure and directing the stream at the areas of the glass you wish to etch.The abrasive will remove tiny pieces of glass from the surface resulting in an etched, frosted finish.

Abrasives

The most common types of abrasives used for glass etching are aluminum oxide and silicone carbide. Although these abrasives are more expensive than silica sand, they are actually more economical to use than regular silica sand because they can be re-cycled many times and save labor because they cut into the glass much faster. Aluminum oxide is a widely used abrasive for etching glass but it generates static electricity which causes the dust to stick to the back of the glass making it difficult to see what your blasting. Silicone carbide is considered the cadillac of abrasives because it is the fastest cutting and the longest lasting of all the abrasives. Instead of dulling as it is used, silicone carbide breaks into smaller particles creating new sharp, cutting edges. But, it too will eventually break down to dust which will be too fine to blast with. Abrasives are referred to by size or grit number..the smaller the particles the higher the grit number. Larger grit will cut faster, leave a coarser finish, and generate more heat. The smaller grit size will cut slower and leave a finer, smoother finish. The most common grit sizes for etching windows and architectural size projects are 100 to 150 grit. For a finer finish on glassware and trophies 150 to 200 grit is used. For small micro blasters or pen type blasters use 220 to 400 grit. When blasting wood signs we recommend grit sizes of 30 to 80.

Resists

When you decide to etch a design on your glass or mirror project, you must determine which parts of the glass will be etched and which parts will be clear. You accomplish this by covering the glass with a vinyl or rubber material called a resist. because it resists the abrasive and prevents the etching of certain parts of the glass. Your design is drawn onto the resist or you can use a photocopy glued to the resist...You then begin hand cutting the design using an exacto type hobby knife. When all the areas of the design have been cut, you remove areas of the resist where you want the etching to be created. Resist is specified by its thickness, usually stated in mils, and by the type of material, typically vinyl or rubber. Selecting the proper resist for the job is very important. Controlling cost is essential for making a profit. You want to use the least expensive resist that is adequate for the job. You don������¯������¿������½t want to use a resist that is too thin and might blow off under pressure, and you certainly don������¯������¿������½t want to use an expensive, rubber resist that is heavier than needed. Heavier resists are thicker and more difficult to cut and blast finer details. For most shading and surface etching a 4 mil vinyl is recommended. For shading and light carving 4-8 mil vinyl is appropriate. Medium depth carving demands a 10-15 mil vinyl but it is thick, hard, and difficult to cut. When it comes to medium to deep carving of glass you should be using a rubber resist, usually between 18 and 30 mil. We also use the 4 mil vinyl, inexpensive 5 mil polyethylene, or even contact shelving vinyl to protect the back of the project as well as any areas that need to remain unetched. You can easily over-spray or scratch the glass when working with abrasives. A little bit of preventive preparation goes a long way.

Choosing The Right Air Compressor

The air compressor is the machine that creates the compressed air needed to run the sandblaster. We have found that the smallest compressor you can use to power your sandblaster is a two horsepower unit that generates at least 6 CFM at 100 PSI. CFM represents the cubic feet of air per minute or amount of air the compressor generates and PSI means pressure per square inch or air pressure the compressor puts out.A siphon blaster requires more cfm per 100 psi to work efficiently, while a pressure blaster requires less cfm. Even though pressure systems are more expensive than siphon systems the increased speed at which they etch the glass more than compensates for the added expense. Make sure the compressor you choose has an air tank of at least 20 gallons. The larger the air tank the less the compressor has to run to fill the air tank to the proper air pressure. Check the specifications of the sandblaster you are purchasing to determining the size of the compressor you will need. Your budget and the type of blaster will be the final factor in choosing the right compressor

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