Remove paint, rust, or residue from glass, metal, stone, and wood quickly and efficiently. Remove scratches or unsightly marks through sandblasting. Sandblasting used to be something that could only be done by a professional who had access to expensive machines. Now, air and sandblasting machines are more affordable for do-it-yourself projects, so you can even safely sandblast at home.
What is sandblasting?
Air and sandblasting are sometimes called abrasive blasting. It is a process that uses pressurized air or water to remove abrasive substances from any surface. In technical terms, it is a technique that uses abrasive granulates with pressurized air against any surface to clean it or remove particles to prepare the surface for paint or other projects.
Stationary or Mobile
The machine used for sandblasting is either mobile or fixed to make it easier to move around and hooked up to an air compressor. The machine works a lot like a paint gun. This blasting gun offers a variety of sizes of nozzles that can be attached for specific needs. The nozzles are used to spray granulate onto surfaces of what is being sandblasted. Sandblasting machines are built to run at a higher pressure. However, sometimes all that is needed is to preserve and clean the surface. For these less intensive projects, adjust the air pressure lower.
Sandblaster machines come in three basic types:
Abrasive Vacuum Sandblasters
When all you need is a little spot cleaning or to work on a small project, a vacuum sandblaster is a way to go. A vacuum-style machine can be attached to a small air compressor. This type of machine provides a reduced airflow of about 66 GPM gallons per minute. It doesn’t have to look fancy to get the job done and only needs to consist of a hopper tank, a hose, and a nozzle with a gun-like trigger. Aggregate is pulled through the hose by the Venturi effect. Pull the trigger, and aim to start the process.
Air Powered Pressure Sanders and blasters
With a capacity of a minimum of about 800 GPM, an air-powered pressure sander is intended for professional use. The output flow and pressure of the gun are regulated and kept constant, which means that the end result is an intensive and very powerful stripping for large projects and tough jobs. This machine will need a lot of airflows to work properly, so a high-power compressor is needed. But, the hose length allows for ease of movement, making it fully mobile. Of course, there are various pressure and nozzle adjustments available to custom fit the pressure with the work that needs to be done from low to high-pressure techniques. The way a pressure sander works is that the aggregate is subjected to pressure while in a sealed tank. The gun trigger is pressed to release pressure used to force the aggregate out.
A sandblasting cabinet is perfect for DIY work with auto mechanics or glass, allowing precise and detailed work without leaving behind a mess. It is a home workshop sander that is intended to be used for indoor scraping work on smaller projects. A sandblasting cabin usually works like a vacuum or air-gun sandblaster enclosed in a “sleeve box.” Slip your hands into the fixed gloves on the cabin chassis, and start blasting. To make sure you work precisely, keep an eye on what you are doing through the window located on top of the cabin. For better visibility, some units provide extra lighting. A sandblasting cabin typically operates with a lower power compressor of about 66 GPM minimum, and some can connect a vacuum cleaner.
Selecting The Right Nozzle
Choosing the right nozzle is very important. Make sure the one you choose is intended for the type of job you are using it for. Match up high or low pressure, along with a few other considerations.
Choose the right profile, either cylindrical or Venturi. Keep in mind that Venturi nozzles are usually the preferred option since cylindrical nozzles tend to be a lot less efficient and are seldom used.
The nozzle length can easily be selected depending on the size of the air compressor. Short nozzles are going to demand high airflow rates than longer nozzles.
Depending on the type of project you are working on, the interior diameter of a nozzle will matter. Nozzles range in size with an interior diameter of less than 18” to 1/2” or bigger. Generally speaking, wider nozzle diameters mean you will need more airflow. Projects that require low pressure are going to call for very fine abrasive granulates. Also, consider air consumption. Be sure to choose a nozzle with the proper air requirements for your projects. For instance, a vacuum blaster fitted with a 1/8” nozzle will consume about 66 GPM, whereas one with a 1/2” nozzle will consume about 2,500 GPM.
The material that the nozzle is made of is going to make a difference in sandblasting. For instance, Tungsten carbides are generally considered to be the normal material used since it is fairly strong. The only downside is that it tends to be heavy and lasts for about 300 hours of use. There are also various silicon nitrides, boron carbides, and ceramic nozzles that typically last longer, about 500 to 700 hours of use, and are lightweight.
How Do I Choose an Aggregates
Aggregates are inert granular materials like sand, gravel, or crushed stone and are used like sandpaper in the sandblasting process. There are various abrasive aggregates to choose from. Each aggregate is a different size, shape, and density. Here are the most popular types:
The metal shot is great for preparing surfaces for painting and for heavy stripping. Its high abrasive power makes it a great choice for rust removal, surface preparation, and scouring. Its high abrasive power benefit, however, is also its downfall if you want to do detailed, precise work. The metal shot is not the best choice for finishing. Another aspect to consider is that the shot is not recyclable.
Corundums are a good choice for a variety of surface preparation work. It can easily be used with any type of blasting machine, and particle sizes are normally less than 1/8”. Since it offers high hardness, it produces very little dust, and knowing that corundum is recyclable, it is a popular choice.
The glass bead is soft abrasive with small particle sizes, which makes it a great choice for polishing, deburring, cleaning, surface finishing, especially used at reduced pressure. Most of the glass bead is made with recyclable materials.
- A dehumidifier filter helps to cut down on clogging within the blaster.
- The pressure gauges show you what the outlet pressure is for the aggregate.
- The safety valves help to prevent accidents that are caused by too much pressure.
- The tank volume is relative to the nozzle size and helps to determine the use time.
- A thread sealing tape works a lot like Teflon that plumbers use. Ideally, every time you change the nozzle, you should put tape on the thread before mounting to keep everything sealed tight.
- The funnels are used to fill the granulate vessel.
- The gun provides a trigger for operation and is on the nozzle mount.
- A compressor will work at optimal capacity when the pressure and horsepower are at the proper ratio.
Don’t be an accident statistic. If used improperly, a sandblaster can be dangerous. Many accidents occur due to a rusty tank or faulty pressure controllers or regulators. It’s important to take certain safety precautions, such as wearing sandblasting helmets, an apron, and a pair of gloves. Protect your ears from noisy compressors with noise-canceling headphones with earplugs. Be sure to follow all manufacturer recommendations for use. Some machines require periodic inspections or require that you follow special regulations.