Blast Cabinet Parts Cleaning

One of the most daunting tasks with any restoration is cleaning parts. Grease, grime, rust and corrosion have taken over your car. Now it's time to reclaim it, making it look showroom fresh again. The best way to do that is by blasting components clean in an abrasive blasting cabinet. There are other options such as chemical dipping and stripping and the old wire wheel and brush method, but nothing seems to prepare a vehicle's various surfaces for refinishing as well as abrasive blasting. And with the price of home workshop blast cabinets and larger compressors becoming more affordable, many restorers either have the equipment or know someone who does.


Abrasive blasting and blasting media is an industry and science unto itself. You could fill a good size book with stuff you should know. However, we will attempt to provide some basic information that should help out some newcomers and prevent amateur restorers from destroying some valuable original parts.


Most restorers are familiar only with glass beads as a blasting abrasive. What most people are not aware of is that glass beads are available in a couple of different grades and several "grits" that are equivalent to sand paper grits. For instance, a #8 glass bead is equivalent to 70-100 grit abrasive paper in coarseness, however, unlike sandpaper, glass beads do not remove the base metal when cleaning. In fact, glass beads when used at the correct pressure in with high quality blast cabinet will actually polish the surface instead of roughing it up.


There are two basic grades of glass beads, industrial grade (mil-spec) and general automotive. Mil-spec (military specification) beads are oblong in shape and very uniform in size and used for operations such as shot-peening aircraft parts. As you might imagine, mil-spec glass beads are more expensive and unnecessary for general automotive cleaning. Standard grade glass beads are less uniform in shape and consequently less expensive. The uniformity isn't an issue because glass beads actually fracture and break up into sharper particles with use. When they fracture, the glass beads will quit polishing the surface of parts and actually provide a rougher, frosty appearing surface, great for painting or spraying with clear paint for that "as-cast" new look.


Glass beads do an excellent job for cleaning most aluminum alloys, painted steel components and items with only surface rust. However, there are other cleaning tasks involved when considering different blasting media. If you are preparing a piece for powder coating, for example, the surface requires an "anchor pattern" for the powder coating to adhere to, or if the rust is imbedded as opposed to surface rust, glass beads will not get the job done. For those particular tasks there are various types of aluminum oxides that will leave an anchor pattern or get down into the metal and remove the imbedded rust. They are available in a number of different grits depending upon the surface finish desired and the amount of substrate material that needs to be removed. Some aluminum oxides have trace elements of iron (they are reddish brown in color) and shouldn't be used as these iron particles will imbed into the part being blasted and promote future rusting.