If you are restoring an old car or just fixing up your present ride, you may find yourself needing to clean up some parts before painting. In the old days, one would use a “sand blaster” to expose the raw base material. Today a similar technique is used but it referred to as “media blasting.” According to our friends at Kayser Chrysler Center of Sauk City, WI, a full-service, Dodge, Chrysler, Jeep, Ram dealer, this is because sand isn’t used much anymore due to the health risks of inhaling silica particles.
What you can clean
Media blasting is especially good for cleaning the rust off of metal parts and has been used for decades to do just that. Today, you can even clean up plastic, wood and other materials with a media blaster. As you probably imagine, a media blaster is a handyman’s dream.
How they work
Consumer media blasters use pressurized air to shoot tiny pieces of material (media) out of a nozzle to strip off the surface covering off a part. It’s sort of like pressure washing, only at lower pressures and it doesn’t use water, it uses air and the media that is mixed in with it. The most commonly used media include plastic beads, glass beads, ground-up walnut shells, and aluminum oxide.
Types of media blasters you can buy
Typical consumer media blasters are closed boxes with an internal blasting gun and a pair of heavy-duty gloves built into the structure. The smaller ones cost about $200 not including an air compressor. Larger standing cabinet blasters with about many cubic feet of internal space are more expensive – usually $600 and up. The media generally cost less than $50 for a 5- gallon bucket, but most media can be reused repeatedly for quite a long time. The general specification for the compressor used with media blasters is that can handle a minimum of 80 psi at 5 cubic feet per minute.
For big jobs
For larger objects, such as wheels, body panels or even entire frames, you can build a simple enclosure with 2 x 4s and plastic sheeting. This sort of media blasting project will require a separate handheld gun and personal protective equipment. If you aren’t doing this sort of thing often, you may want to look into renting the equipment from a local rental supply store. You can also bring your parts to a business that will do it for you.
How to media blast
The rule of thumb for media blasting is to use the lightest abrasive and lowest pressure necessary to start. Don’t forget that the softer the target material, the gentler you need to be. It’s always a good idea to test your material and pressure setting first on a section of the part that isn’t seen. If it takes off the surface covering quickly then you are all set. If its slow going, then you need to step up the air pressure.
About the media
Walnut shells are dirt cheap and eco-friendly but only last for one use. Plastic beads can be used multiple times. Both are gentle enough to strip paint on metal, although they aren’t abrasive enough to remove rust. To remove rust, aluminum oxide is the best. Not only will it strip off all the paint and rust, It can even smooth out minor scratches and gouges. The best part of the aluminum oxide media is that it can be used over and over.