VCCA Home Forums TECHNICAL - GENERAL Body - Sheet Metal, Paint & Wood Media blasting with walnut shells

I am in my final stages of preparing my body parts for painting. This winter I used Black Diamond Media Blasting Material to blast the fenders, doors, and hoods. I used the fine 30/60 blend. The product is made of recycled materials, mostly coal slag. It leaves a slight tooth finish to the metal which I assume is good for doing body work on and a satisfactory paint surface for using sealers and primers?

I now want to blast the body. A local body shop, I may use to paint the car, is recommending I use walnut shell media for blasting. They are concerned with the potential for warping, and note that the metal surface will be smooth, and metal prep for painting will be minimal.

Has anyone used walnut shell media with good results? I do not have a lot of rust issues and the remaining paint on the car is worn thin? Why should I worry about warping when I had non when I did my other parts? Perhaps, if I am worried about the roof warping I should just use walnut shells there?

Thanks, Mike

My car was disassembled and blasted by one of the top restoration shops in the country and that is what they used. Sorry no pictures on this pc.

Look in the tranny opening. A product called Shelblast.

Mike

Walnut shell blast media was used in the aerospace industry for paint stripping aircraft skin aluminium alloys and engine compressor cleaning because of its softness prior to the invention of the many different blast media types available today. I would use it just to be safe. If you use a harder media and create waves and stretches you won't see them until you block sand prior to color coating and then it is too late.

On a number of 'restoration' type TV shows, they use baking soda for blasting paint off without heat damage. I have not tried this.

Cheers, Dean

Its my understanding that soda blasting is the most harmless on the metal, but you have to do some extra prep before paint after using it, I would think walnut shells would be just as good as softer media and if you didn't experience warping before then you're likely going to be fine. You know what panels could have an issue already (roof, hood, doors) so if you're careful I think it'll come out okay.

Heat and force cause warping. Soft blasting media and low air pressures take more time and are not as effective in removing pitted rust but reduce the potential for warping. I have often used sand at reduced pressure on the thicker old Chevy sheet metal without warping. Care and experience is critical. Most sand blasters are more interested in production speed and experienced in structural steel so are not good candidates for your old Chevy parts. Restoration shops and specialty blasters are better bets.