One of the first things I decided to do after purchasing my roadster body was to get the thing down to bare metal. Somebody over the years had coated it in black rattle-can paint and how many additional coats of paint were under that, no one knows. I think I lost count at four. Being the ever-so-determined person I am, I figured, what the hell, let's see if we can strip all the paint off this puppy-at least enough to where I would be able to weld in a couple of patch panels, build the subrails, and hang the doors.
That was a bad idea. I started by using Klean-Strip paint stripper I purchased at a local hardware store. The label said it cuts through multiple layers in a single coat, so I applied two coats in one night with the end result being a little short of promising. The next night I returned with an even tougher stripper that I'm sure Al Gore could claim melted the polar caps or something. This stuff kicked off well and looked like it might be the ticket, but alas, all I had were some grimy panels and a smelly shop at the end of the evening. The chemical stripping product removed the paint fairly easily, but proved ineffective on surface rust. A quick inventory revealed that if I quit now, I'd only be in the hole about 90 bucks and roughly 10 hours of my time. A simple math equation followed, and I was soon asking myself why I hadn't just shelled out the extra couple hundred bucks to get the body sandblasted in the first place; then I could've spent the last two nights sitting on my tuckus instead of inhaling fumes.
I made a few inquiries with some of the local car guys who like rusty old junk like I do, and they all pointed to Orange County Sandblasting. The company has blasted hundreds of old hot rod bodies and the owner, Don Gravley, is a hot rodder as well-so suffice it to say, he gets it. Don uses a combination of walnut and glass beads that is constantly being mixed and maintained in the booth while blasting. The end result for my rod was complete removal of all paint and rust with a slightly textured surface, perfect for a coat of primer once all the metalwork is completed.
Impressed with the capabilities of Orange County Sandblasting, I was curious as to how someone could get the same results on a smaller scale out of one's home shop. I was familiar with TP Tools from a trip I had made the previous year to the company's new facility and knew the guys there were the ones to talk to. Not only does TP Tools manufacture America's number one-selling blasting cabinet, the Skat Blast Cabinet, its catalog is downright dangerous in the hands of a gearhead with a credit card. TP Tools sells everything from air and bodyworking tools to welding supplies. To support its cabinet business, the company also carries nearly a dozen different blasting medias to cover every possible job. I was a little curious as to why TP Tools carried so many different abrasives to do what sounded to me like the same job, so I cornered one of the company's tech guys, Carmen Ferraro, on the phone and had him break it all down for me, layman style.
As you can see from the chart on this page, the Skat Blast abrasives are classified by the time it takes to remove the finish from a 6x6-inch area on a steel fender. A couple of the medias had similar times, which leads one to believe that they do the same job; while that's true, we'll get to the real differences between all of them in a minute. Among the nine abrasive medias listed, you can see that four of them are in bold: Glass Beads, First Choice, Speed Bead, and Skat Magic. These are TP Tools' top sellers and the most used abrasives on the company's Skat Blast Cabinets. While very similar, each of the abrasives on the chart has its own specific application.
Skat Magic and Glass Beads are the company's most popular abrasives sold. Skat Magic is a medium-grade abrasive created from recycled, crushed automotive glass that gives it its white color. This is an excellent media for removing paint, scale, and rust from most surfaces and cuts quicker than the relatively finer Glass Beads abrasive. Glass Beads is a finer media than Skat Magic, which makes it ideal to use on softer metals like copper or brass. For example, if you wanted to polish all those brass fuel fittings but needed to remove the 40 years of oxidation and crud built up, the finish left by Glass Beads would be much less aggressive than that left by Skat Magic, leaving the work at the buffing wheel to be considerably easier.
On the other hand, notice the time difference it took to clean the section of fender between the two abrasives. Skat Magic was much faster, making it the ideal abrasive for most all applications, save for use on some softer metals. The reason Skat Magic is more aggressive has to do with the way the glass is crushed when the abrasive is produced. The recycled glass for Skat Magic is crushed by a roller-type mechanism that leaves the glass particles with sharper and more defined edges, which cut faster than Glass Beads. In short, if time is of the essence, and the semi-aggressive nature of Skat Magic is not an issue, it's definitely the abrasive to use.
First Choice is another popular media sold by TP Tools. Made from synthetic materials, it contains no aluminum oxide, which puts it in a similar category with Skat Magic and Glass Beads. The big difference is the aggressive nature of First Choice, which makes it a faster abrasive than Glass Beads, but a little too aggressive for most common automobile restoration work. This media is sold mainly to industrial shops where quick removal of scale, paint, and rust is more important than the finish and treatment of the metal; think farmers, steel workers, etc.
Speed Bead is the next media to consider. Similar to Glass Beads in terms of content, Speed Bead is the first abrasive mentioned here that contains aluminum oxide. While this means Speed Bead has a faster cut time than Glass Beads, it must be considered that the metal in Speed Bead can impregnate itself in the material being blasted. This may not be ideal if the material is to be polish or if foreign objects are not desired in or around the surface, such as on an aluminum intake manifold. The selling point of Speed Bead is the fact that the aluminum oxide added, about 50 percent, makes the media the best-lasting of the aforementioned abrasives. This may not mean much for the lone guy at home, but Speed Bead could prove very beneficial for a larger shop using its blasting facilities daily.
There are other abrasive medias sold by TP Tools that can be considered as well, and although they may not sell as well as the featured four, they all have their place. Walnut Shells Abrasive is an organic byproduct of the agriculture industry and is good for light-duty paint and carbon removal. This abrasive is often used by the aviation industry for cleaning carbon deposits from engine internals, where an aluminum oxide media may impregnate itself. Walnut shells of different forms are often combined with other medias, such as Glass Beads, as was used to blast my roadster body.
The lifespan of Walnut Shells is the shortest of the abrasives discussed here due to its ease of pulverization. Skat Plus Plastic Abrasive is a great abrasive for cleaning plastic and fiberglass surfaces because of its rather unaggressive nature, but it will not remove rust or other corrosion. Plastic Abrasive is relatively safe to use around unmasked glass if the media is not tainted, and it's good for removing paint and light oxidation. Unlike Walnut Shells and Plastic, Steel Grit, Aluminum Oxide, and Silicon Carbide all contain metal and are aggressive abrasives. Used mainly in the industrial field or where heavy paint, rust, and scale removal is necessary, Steel Grit is extremely fast-cutting on rusty metal and leaves a smooth finish on metal. Aluminum Oxide and Silicon Carbide abrasives are extremely efficient on rusty metal and are among the longest-lasting abrasive medias due to the ability to withstand pulverization. The drawback to this aggressive nature is the shortened lifespan of the blasting components.
Choosing which abrasive to use can be determined by many different factors. A rusty Ford axle, for example, could be blasted with any of the abrasives mentioned. The difference is going to be how long it takes to remove all the rust and scale, and the finish that is left when the job is done. If it were a brass or copper item, such as a tank or catch can, a less-aggressive abrasive would be more appropriate. Although TP Tools recommends Skat Magic to the majority of its customers because of its longevity and medium aggression, that doesn't mean it's right for every application. Other abrasives may yield a better finish or get the job done quicker; just remember that the abrasive is doing the job, not the air pressure. TP Tools recommends 80 psi on all of its blasting cabinets, and Don at Orange County Sandblasting says he runs slightly less than that for most jobs. Turning up the pressure will only pulverize the media faster and shorten the longevity of the abrasive.
