Media Blasting, commonly called Sandblasting is a process in which sand, glass beads or some other medium is shot at high speed through a machine across the surface of a hard material until it is sanded smooth. Sandblasting is often done to remove a previous finish on an item, to remove rust, or to prepare a surface to receive a new coat of paint. The kind of medium used to blast the surface depends on how difficult the removal is and how much impact the material can withstand.
1. Selecting the Correct Type of Media
There are many media types available. Some are good for blasting body panels, but most are not. Each of these media types have a different hardness and will react with metal differently including: causing heat and actually embedding in the metal. For this reason we use crushed glass. After much research and many trials, we prefer the excellent results that crushed glass provides (not to be confused with glass bead, which is much larger). Our medium crushed glass is the approximate grain size of table salt.
2. Blasting PSI
Most sandblasters will blast with a large tow behind compressor and blast at 125+ PSI. This will strip metal very fast. However, this creates heat and is very aggressive on the surface of the metal (and depending on the media (like Black Beauty) will actually remove metal. We blast our crushed glass at a very low 45-65 PSI depending upon the surface we are blasting.
3. Blasting Tip Size
Most sandblasters will bast with a #6 thru #8 tip. We blast with a 3/16 (#3) or 1/4" (#4) tip. The smaller tip means more media control and less media hitting the metal at once. Which translates to less pressure on the metal.
Blasting a car body is not about how quickly it can be done. Using a #8 tip, blasting black beauty at 150 PSI, will clean an entire car body very quickly. We have even heard competitive estimates as low as 3 hours to blast a whole car minus bottom (wow!)...But believe me, you will cry at the results and all of the body damage! Using proper technique, it typically takes us anywhere from 6 hours to do a smaller shell to up to 15 hours for a complete larger car (outside, inside, bottom and doors).
5. Blaster Experience
Blasting classic cars takes years of experience and the love for what you do. Pride in your work as well as classic cars is a must. In short, blasting a car body correctly takes time and experience to do it right...