raw442

I will be doing a lot of media blasting on my car and needed to know what media I should use? I know there is sand, crushed walnut, glass, and beads.
What should I use for the sheet metal and then on the frame, rear end and other suspension?

joe_padavano

The answer is, it depends.

There are different types of media for different applications, but first let me stress that you must use extreme care when blasting sheet metal. DO NOT simply point at the surface and blast, you're guaranteed to warp the metal from overheating. Use lower pressure and blast at a shallow angle, moving around to avoid heat buildup. Thicker frame and suspension parts are no problem, but be careful with sheet metal.

For aggressive rust removal on heavy metal, aluminum oxide or silica based media are very effective. Most of the blasting equipment suppliers have a crushed glass media that is an excellent general purpose blasting media for rust removal on sheet metal as well as thick stock. Glass beads are used for soft metals like aluminum. Plastic beads and walnut shells are used primarily for cleaning (think removing carbon from used pistons) and will not damage the underlying metal, but they are not very aggressive. Additionally, walnut shells are used for cleaning internal engine parts because they will not cause damage inside the engine if there are a few pieces left inside. Finally there's soda blasting for paint removal, but that requires a special blaster. It also will not remove rust, just paint.

Allan R

Are you doing the cleanup yourself? Sometimes for the hassle of what's involved, building containment and clean up after ward it may be cheaper, easier, faster and cleaner just to have a professional shop do the media blasting. You can either let them choose, or specify what media you want used since different grits give different finishes.

66-3X2 442

Beware of soda blasting. I heard or read somewhere that paint companies have stopped warrantying their products if used on a soda blasted unit. I'm not sure but I think it has to do with the adhering of paint/primers on the soda blasted areas. Don't quote me on this but I would check to see if there's anything to it.

joe_padavano

Soda blasting is the standard way to strip paint on aircraft. As with any contaminants, if the surface is not properly cleaned and prepped after stripping, there will be paint adhesion problems. The soda itself is not the problem, it's the lack of proper prep prior to paint.

Al Graaf

Voice of experience here?

Allan R

Not sure why. As Joe mentioned it's used commercially because it's effective. One of the other really nice features of soda blasting is it does NOT harm stainless, chrome, rubber or glass parts.

Bernhard

Some very good post on the topic.
I find it cheaper to take it into a shop. If you do take it into a shop make sure they know how to media blast sheet metal with out putting waves in the sheet metal I have lost many hours fixing media blaster damage.
As soon as the car, frame, parts are striped get them in primer ASAP metal flash rusts very quickly.
Before I start any restoration I start by having the car measured at a quality frame shop. Once the car gets a clean bill of health or has been repaired by the frame shop only then do I take the car apart for media blasting.
Local shops in my area use a hybrid mix to blast sheet metal with. A mix of walnut shell with fine garnet from India. What you are paying for at a quality blasters is there fine tuned skill set and blast media that they have honed, for this type of work. I wood visit local shops and see how and what they are using to strip with.
Old cars are painted with lead paint and have lead filler so when you strip them the lead becomes air born.
This is another reason this type of work is best left for a dedicated shop.
When you look at what type of blasting shops do look at the finish. Some shops with there media that they use leave the metal so smooth that it is as if the car was striped with 100 grit sand paper. While others the surface is like the surface of a golf ball. This is very important the rougher the finish the more primer will be required to fill in the damage.

66-3X2 442

I did not say not to soda blast,what I did say was beware as there are problems using it. Just google soda blast problems and you will see what I'm talking about. You can read forever the pros & cons of using it. Here's the wiki about it.

http://www.crankshaftcoalition.com/wiki/Soda_blasting

Allan R

I just was curious why you said to 'beware' and you've answered that. I never read into your post that you were saying not to. I've only seen the process demonstrated on television, not in person. I guess what they don't say on TV is the details you referenced. Thx.

raw442

Thanks for all the input guys. I was wondering if it would be a better option to have a shop do it. How about much does it usually cost?