"Sandblasting and Restoration" Going to bare metal

Using sandblasting equipment in body repair

Light to Medium Restoration

1. Repair & Repaint: Basic mechanical work is done to put the original equipment components in safe working order. The vehicle receives minor body work and is refinished. The vast majority of “fix-ups” fall into this category.
2. Repair, Replacement & Refinishing: Mechanical repairs as above, but some components are replaced with adaptable modern units, including engines, drive train parts, brakes, etc. Body repairs may be performed with a greater level of detail and expertise. These modifications to original equipment will reclassify the car as a custom in some people’s minds.

Heavy Restoration

3. A variation on #2, except the project takes much longer. The vehicle is partially disassembled to remove rust and corrosion from key body parts. Drive train components, suspension and other underbody parts are cleaned, refurbished or replaced with rebuilt or aftermarket-”new” parts. Body restoration may include a close color match of original paint schemes. Some trim items may be replaced with original or aftermarket replicas. Some cars in this category are often garaged and exempted from everyday use (especially if it looks like rain).

Like New:

4. Just what those words mean. Every attempt is made to restore the vehicle to showroom glory, right down to window stickers, owners manuals and the “right” taillight bulbs. New-fangled repair materials (like body filler!) are not allowed by these most obsessive enthusiasts. Hair splitting abounds in their discussions (and arguments). Fiberglass body panels (except on desirable Corvettes) are scorned by these devotees.

Museum Quality

5. This category applies to almost no one. These vehicles are museum pieces-literally. They are restored to their condition as of a certain date in history (interpretive period) according to a qualified curator. Like I say, this applies to very few cars, but they are out there.

SANDBLASTING 101

 Suction feed blasters are much cheaper, but suffer the same disadvantage of the suction feed paint gun: they use part of their energy in sucking the material up to the outlet, before the actual blasting begins. Suction blasters do not need an expensive pressure tank to operate. You simply insert the suction pipe into the blasting media and...blast.

Pressure feed blasters use a pressurized tank to force the media up through a flexible pipe at high velocity. This design works best: paint disappears almost magically from the panel.

 Sandblasting (at least initially) is fun, but messy. There’s a good reason why so many sandblasting outfits operate in the open air: daily clean up would be a major headache if the work were done indoors. Although sandblasting is primitive, it is effective and low VOC.

 There’s nothing primitive about the finish blasting provides to autobody repair and refinishing. As you remove the old finish from the panel, you immediately notice the finely textured metal beneath. You’re looking at an optimum surface for paint adhesion. It is at this point you’ll begin to see why so much restorative work is done with our trusty sandblaster. When the right grade of sand is used, a panel can be blasted down to the metal, including rust pits!

Speaking of rust, other parts of the car can be cleaned up with a minimum of effort with the blaster. Frame rails, exhaust manifolds, etc. can all be quickly sanitized. Keep in mind that you’re going down to bare steel or iron, so apply a treatment to prevent flash rust until the part is primed, plated or painted.

 Before we get a lot of E-mail from the purists, let me qualify all this blaster information. Anything can be overdone. It is possible to permanently damage a body panel or part with the overzealous use of the blast nozzle. After you reach bare metal...stop.

 What type of blast media should you use? It depends on the surface to be cleaned up. Underbody parts require nothing more exotic than washed beach sand. Body panels are another matter, however, and here’s where personal opinion takes over. Silica sand (36 grit) is a good all-purpose body media. Depending on how fast you want to cut and how careful you are, you can choose from various grades of aluminum oxide, glass bead, or even plastic media to remove paint, rust or corrosion. The exotic media are pretty well relegated to use in booths and cabinets where they can be reclaimed. Forget plastic media unless you’re loaded: the specialized equipment is expensive.

 For lighter touch blasting, ground walnut shells can be used as media. I’ve used them in my pistol casing tumbler for years with buckets of gleaming brass to show for it. Walnut shells will not mark glass or plated surfaces, but are a little more expensive than sand. Also, English Walnut Shells cost less than Black and have the same hardness, etc.

 Siphon blasters start at around $135 while pressure blasters range from $500 up to $3500 and beyond. Of course, these prices don’t include the compressor and all the gadgets that go with it.

 Another word on body work: If you remove door hardware and trim from the body before refinishing (as you should), do it before blasting. You’ll be able to do a more complete job of removing all of the old finish. Just take care that all components that are affected by sand are covered or protected. By the way, you should protect your own body components from blast media as well. A suitable hood and gloves are a necessity. Many paint products retain their toxicity after they dry, so when they are blasted off the fender and into the air, they become a health hazard. If you plan to do a lot of blasting work with hazardous materials, get a supplied air hood. Don’t borrow the painter’s air hood – he’ll kill you.

Sand blasting works for automotive restoration. It helps avoid a lot of hard labor, especially when working with deeply convoluted surfaces (a rusty wheel rim comes to mind). But however you use blasting, do a thorough job for best results.