MTFCA Forum

Back on May 28 2021, I entered a post "Blasting Media for Coupe Body". A photo was included. I received good responses.

Here is what I have decided. I found a local blaster (within 50 miles) who has a mobile unit and uses both crushed glass and soda. He has been in the business for 15 years. I plan to take the two rear fenders and the two splash pans to him. He would use crushed glass on one fender and one splash pan and soda on the other two as a trial run. I believe the splash pan is the thinnest piece on the T.

I would appreciate comments on this plan.

Be careful of anything with soda! It will get into cracks and lap panels, worst, injecting under high pressure into them. Have seen many sweet steel bodies destroyed in about 5 years of very high valued cars. One was a Daytona Super Bird. Fine media, pressure no greater than 90 psi, extra product coming out than normal, keep distance consistence and in a fast random motion. This will prevent warping and heat generation to a minimum.

Hank

Besides heat, blasting media can have a peening effect on metal which can change sheet metal parts' contour. Media embedding in metal or in micro rust pits can cause problems, too.

Would not go nowhere near blasting a body.

The fenders would be OK to blast. Their crown and curvature will hold them in good shape. I would not blast the splash aprons unless you have a rust problem. Paint will come off with paint remover, and there is no risk of the panels being warped. As a rule of thumb, the flatter the panel, the greater the risk with blasting.

Allan from down under.

Henry Lee, Could you clarify what you mean when you say cars have been destroyed by use soda blasting after about five years?

Find someone in your area who does ‘Dustless Blasting’. No heat, no warping, and a preservative to prevent rust til you get it primed. Looks like there may be a couple in your area. Well worth it.

Soda blasting is basically salt, you are injecting into seams, crack, etc. It will not neutralized unless the whole body is submerged into a tank for a good week with the correct chemicals. Might as well go to a beach in the ocean surf and not wash your car and get the same results in 5 years. Not one manufacture of automotive finishes/core products will endorse soda blasting and it voids all warranties.

Hank

Soda blasted parts must be thoroughly washed with lacquer thinner or a mild acid, or your primer/ paint will not stick.

I agree with John. I would never blast the body of any automobile. Not only can it warp the body but it permanently etches and roughens the original smoothness of the steel. It may take longer, but removing the paint with paint remover down to the steel, removing the rust with rust remover and sanding the body smooth with sandpaper is more rewarding, helps you become familiar with the curves of the body and prevents the permanent damage that can be caused by blasting. Jim Patrick

PS. Just out of curiosity, why would you use “crushed glass” to sandblast with in lieu of sand? Glass is made from silica, which is sand. Seems like crushed glass would be much more damaging than sand, which is basically, small particles of glass. I have heard for years that crushed walnut shells are the mildest blast media.

I have sandblasted sheet metal with a pressure pot sandblaster and a 3hp air compressor for decades. Started with a one bag size TiP sandblaster, now called TP Tools. With the relatively low pressure I have never had a problem with warping or hardening thin sheet metal. Couldn't understand the warning cries from people that sandblasting will ruin sheet metal, that is, until I took some model T splash aprons to a commercial blaster and they were ruined. I would never take anything to a commercial sandblaster again, but I still use my at home sandblaster. Wore out my first sandblaster and have since moved up to a 1 1/2 bag size blaster and a 5 hp air compressor. I use about 90psi air pressure, the commercial blasters must be 175-200 psi, maybe more, to do the kind of damage they can do. I have used a small syphon feed sandblaster too, they are inexpensive, but just dont do the job, not for big things like a wheel rim or fender. I have one for a sandblast cabinet for small stuff. But if I really need to do serious blasting I do it myself with a pressure pot sandblaster outside in the sun. For media I use the cheapest cleanest stuff I can find, right now it is contractor sand from Home Depot. It is white and looks like silica sand I bought at the industrial tool rental. Blasting outside I cannot reclaim the sand so I go thru quite a few bags of the stuff, about 1 bag per 30 minutes. For the blast cabinet I spend real money for good stuff since I continually reuse it, black aluminum oxide.

If you are going to blast an entire model T body, paying someone else to do it will be prohibitively expensive. For the same cost, or less, you can buy your own equipment and do it yourself. To blast an entire coupe body, it will take probably 2 days, 16 hours, 32 bags of sand, minimum. Rusty metal will start to rust again right away depending on the humidity. Blasting one section at a time in a few hours, treating with metal prep, rinse, dry, and prime, then repeat for the next section, may provide better results and allow you to do this project over the course of days or weeks at your convenience.

BINGO Jeff! 40 years plus with no warping, patience’s is the key! Nasty job to do but done correctly the results are without question.

Hank

Henry Lee, Some are saying, "never use blast cleaning on a T body". As I understand what you are saying, is it is OK as long as certain precautions are used by an experienced blaster.