How to Use a Sandblast Pot
Properly using a sandblaster ensures your safety while sandblasting and improves the results you will get while sandblasting. In many ways the actual use of the sandblast pot or sandblast cabinet are easy to understand. However for maximum results when using a sandblaster, it is important to understand proper equipment setup, safety equipment requirements, and a few details about proper technique. We will cover all that and more in this tutorial on how to use a sandblaster.
How to Use a Sandblaster Step 1 - Select and Setup Equipment Properly
While it is obvious that setting up equipment will be the first step, there are a few key points to know about equipment setup for sandblasting and how it will impact both your production and ability to effectively sandblast. First, is the type of sandblaster your using. There are pressure and suction sandblasters. Suction blasters are meant primarily for touch up work and not for blasting off new paint or profiling a surface for the first time. Pressure blast pots are what should be used for the majority of blasting work. If you have a sandblast cabinet though, a suction blast cabinet can be used for first time work (see photos below for each type of blast equipment). In addition to a proper sandblast machine for your work, you should also ensure you have a properly sized compressor and air hose for your sandblasting work. Compressed air and your sandblast nozzle size is the number one factor that determines sandblasting speed, specifically volume or CFM of compressed air. Larger sandblast nozzles will allow you to blast faster but require more air. To maximize productivity, you should consider purchasing or renting the largest CFM compressor you can afford. More on compressed air for sandblasting can be read here. After having the sandblast pot and compressor determined, next you want to ensure you use properly sized air hose both to your sandblaster and to the blast nozzle. Large diameter air hose is important because it will help ensure your air pressure and air volume remain high throughout your blast system. For every 1 psi of air pressure that is lost due to restricted air hose or long air hose length, there is a bout a 1.5% reduction in production. For best results use an air hose to your blast pot and to the blast nozzle that is 4 times the size of your blast nozzle opening. A final step in selecting and setting up your blast equipment is to ensure you have proper safety gear and your equipment is safe. Specifics that are required for blasting include a OSHA certified blast hood respirator, dead man safety system on your blast hose, and a Carbon Monoxide monitor if delivering air to your operator from a compressor. You also want to inspect your air line for any bumps or wear and to verify your blast hose has safety cables securing the line across any connections to prevent your blast hose from starting to whip if it would ever loose connection to another piece of the blast hose or to the blast pot.
How to Use a Sandblaster Step 2 - Connect air to the Blast Pot, Adjust Pressure to Sandblaster & Hold the Blast Hose Safely, & Adjust Blast Media Stream
After you have reviewed that you have all proper equipment set up, you can connect the supply air to your blast pot. You will then have one person who will be in proper safety gear and will hold the blast hose while another person stays at the sandblaster to adjust the blast media stream. The blast hose needs to be securely held which is usually best accomplished by holding the hose against your shoulder and holding the blast nozzle with both hands or by holding the hose under your arm for extra stability (see photo below). You will then begin to adjust the pressure of your sandblaster. Pressure is another key factor that impacts your sandblast production, surface profile, and amount of removal you will accomplish. For thick steel you will usually use the highest pressure your compressor will provide but for softer and /or thin surfaces like wood cabins or automobiles you will tend to use lower pressures. If you have any concerns over damaging the surface of the product your blasting, you should start with the blast pressure low and gradually increase so that you do not harm the surface of the product your blasting. Common surfaces that will be best to use a low blast pressure and softer blast media like walnut shells or fine crushed glass include log cabins, fiberglass, glass, and automobile frames / bodies. The next critical step is to adjust the abrasive media flow to your blast pot. The key to getting best results when adjusting the blast media to your sandblast pot is to realize you want the amount of blast media in your air stream to be relatively small. Specifically, the person at the blast pot can start with the blast media valve closed and open the valve slowly until you see the sandblast air stream discolor slightly. Another common method to adjust the amount of media is to slowly open the blast media valve until you hear a distinct whistle and then you can open the valve slightly more. We tend to use the method of observing the blast media stream.
How to use a Sandblast Pot Step 3 - Blast the Surface Using Optimum Angles
Now you have your equipment, air, and media all setup and adjusted. The last step is to begin blasting your products surface. In general the most efficient way to blast the surface of a product is to use a 90 degree angle (meaning straight on toward the surface). If you have concerns over excessive removal or damage to the surface because the surface is soft you can also try to use a slight angle.