"Sandblasting for Kilnformers 101"
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Where to locate your sandblaster
This tool generates both dust and noise. The noise is from both the compressor and the dust collection vacuum. Either of these could be located in a room adjacent to the blasting setup, or even outside, to minimize the noise that you are exposed to while you are sandblasting, but not everyone has that luxury. Wearing noise canceling or sound dampening ear protectors is a good idea.
This is also a tool that can create a fair amount of fine dust which gets in the air and lands on the floor. Having a well sealed cabinet and an externally vented dust collector will minimize this. During the actual blasting there may not be any dust propelled into the room. But, when abrasive is being added to the system or the cabinet door is opened dust will escape from the cabinet, and wearing a mask is wise (in particular, a NIOSHA Particulate mask fitted with a P95 filter). Installing an exhaust fan in the room for use during these times will prevent this dust from finding its way into other areas of the studio.
Customizing your sandblaster
Even when you purchase a complete system, there are a few things that may make use of the blaster easier. Most important is to install an extra light into the cabinet. There is never enough light in these dusty cabinets, and I’ve found that a second one is helpful.
Secondly, have some sort of rubberized surface on the floor of the cabinet to protect the back of your pieces from scratches. I’ve used some rubber floor mats with a cut-out, open pattern. This allows the abrasive to fall into the bottom of the cabinet, but provides a softer surface for the glass.
It is also helpful to create some sort of holder for the glass within the cabinet so that you don’t have to constantly hold the glass with one hand while you hold the nozzle and blast with the other. These can be made of wood and a few nails, and can make blasting much easier.
The dust collection setup of most commercial units can also be improved. The particles generated within the blast cabinet are so small they can pass through basic air filters. It is important to upgrade to HEPA (High Efficiency Particulate Air) filters both for safety and to prevent dust from making its way into the dust collector motor. There are also dust collection reservoirs that attach between the blasting cabinet and the vacuum to remove particulate material before it reaches the dust collector ("Dust Deputy").
Using the sandblaster
First, the compressor is turned on and allowed to build up maximum pressure, at which time the compressor motor will stop running. The valve from the compressor to the blaster or pressure pot is opened as well. Depending on your type of setup, there are a couple of pressure valves that have to be set – but these are unique to your system so I won’t try to go into that here. All systems will have one valve that controls the pressure of the air and abrasive being propelled at your glass. You will adjust this depending on exactly what kind of blasting you are doing. Ballpark numbers would be: light blasting around 15-20 psi, surface blasting around 30-40 psi, deeper blasting above 65 psi.
Before you open the door to the cabinet, turn on the dust collector vacuum to exert negative pressure on the cabinet. Then, open the door and put the glass into the cabinet. Insert your hands into the gloves built into the cabinet. Grasp the hose with a nozzle that will be in the cabinet. Hold the nozzle a couple of inches from the glass, and initiate the air and particle flow through the nozzle by either pulling the trigger or stepping on the foot pedal, depending on your particular setup. It’s best to position the glass in a position relative to the lights so you get reflections, which will help show you the effect of the blasting. Shiny glass will develop a matte finish as it is blasted. Use a slow, deliberate back and forth motion as you blast across the piece until the entire surface has been blasted. Then, remove the glass from the blaster and examine for places you may have missed; and then return it to the cabinet and continue blasting until the job is done.