Blasting Cleaning Basics
Sanding off rust and old paint is extremely labor-intensive. Someone must have thought, "There must be a better way?!" Enter blast cleaning. Blast cleaning gets right down into rust pits and other areas. Compressed air blasts an abrasive at the frame or body part to remove all rust and old paint down to bare metal. There are five different types of blast cleaning methods. Only four of these methods can be used in auto body work.
Dry grit blasting (sand blasting) with a pressurized supply system. This uses a large, heavy-duty compressor that blasts various types of sand or grit, depending on the application and need.
Use sand blasting on chassis areas but avoid using it for body panels because it is too powerful: it may blast right through the panel. And if it doesn't, the high pressure may create ripples in the metal. If you must sand blast using a pressurized supply system, use a fine grade of sand at low pressure. Avoiding damage also depends on your expertise. A dry grit blasting (sand blast) suction supply system works well for the do-it-yourselfer.
Dry bead blasting employs glass beads. The beads remove paint and other contaminants without damaging the part. But the process is slow and can leave a "spikey" surface that is hard to clean.
Vapor bead blasting is more expensive than dry bead blasting. But it is a better system that provides a polished surface to gear box casings and cylinder heads. Pressurized water blasts the glass beads onto the surface. This method closes the grain of the aluminum surface, which provides the even finish.
Shot blasting employs round steel balls and is suitable only for heavy industrial applications. Because it is extremely abrasive, it is not suitable for automotive work.
For the best result, hire an experienced professional to sand blast your parts. However, you can do the work yourself. Before blasting, remove all grease and undercoating from the part. (Do this because it requires a lot of time to remove these by blasting. And while you are blasting away grease and undercoating, you may damage the part itself. ) Remove all mechanical components and wiring from the part. Plan to sand blast well away from your home, workshop or anything mechanical like vehicles and other shop equipment to avoid getting the sand everywhere. Cover items that cannot be moved with thick tarps. Cover glass, too, since sand blasting can easily etch it.
You can use a small, inexpensive gun with a smaller compressor, except that you will not be able to operate it continuously. Instead, you will have to wait every so often while pressure builds up in your smaller compressor.
After you your used or antique part has been sand blasted, you will find it is much easier to work with it.