Blasting/Stripping only underside

[r-mm]

Hello all - I'm returning to the metal work on my '65. The car has quite nice paint and gaps and I don't want to mess with them. I will be doing welding on the entire rear shelf, rear kick and partial floors. I don't have space for a rotisserie so stripping the underside at home will be a chore. It has the original and maybe an additional layer of messy undercoat. I had my Alfa fully media blasted by a firm who knew how to do classic cars - it was $1400 well spent - but the Alfa got blasted inside and out top and bottom. I don't know if I believe someone can media blast just the underside with no damage to paint.

Surely I'm not the first to ponder this problem. Curious to hear any ideas.

[jim amato]

Dry ice blast

[Hugh Lindberg]

I just inquired about blasting the underside on an Alfa without damaging the paint. The shop said no way. They tried one time and had to pay to have a car repainted. We are going to scrape by hand. Ugh...Good luck!

[mac73s]

If the car is stripped of its suspension, engine and transmission, you might consider a body cart (Stoddard makes one that I have used). Other than the four posts where the cart bolts to the body, it will afford complete access to the underside if you don't mind working on your knees and back as it is not very high. You'll also have crawl over the side rails to get under the car.

[r-mm]

Dry ice blast

Can you share your experience? I spent an enjoyable hour watching dry ice blast videos last night but it appears to be a very light clean in its typical application. Its also not all that easy to come by - I tried to have the Alfa done but no one wanted to quote.

[r-mm]

If the car is stripped of its suspension, engine and transmission, you might consider a body cart (Stoddard makes one that I have used). Other than the four posts where the cart bolts to the body, it will afford complete access to the underside if you don't mind working on your knees and back as it is not very high. You'll also have crawl over the side rails to get under the car.

Thanks I have seen these and could build one but my instinct is that I'll either find someone to do the work or go all-in and build a rotisserie. I do not have the vertical or lateral space for an octagon style so it'd have to be a skewer style. No an insignificant investment of time, steel, space and money.

[NorthernThrux]

One thing to consider is the the body in the raw isn't very heavy (~650 lbs). You could suspend it from your rafters (2 or 4 point depending on if you want rotation abilities) possibly depending on your garage construction. That's extremely space efficient.

I did this when I was building motorcycles. Of course they only weigh 400-450 lbs, but it was cheaper and more space efficient than having a motorcycle lift and more flexible in terms or orienting the frame. I used a 400 lb Harbor Freight electric winch at each end for height adjustments. $99 each on sale a decade ago.

[uai]

I think there's a benefit in uploading another before after of dry ice. If your undercoat is not pvc based it's worth every penny.
I got rid of all the Wax undercoat of my car and could clearly see where I got a little rust.

[r-mm]

That looks nice, can you share how you went about the blasting? Deliver shell to a company, rent a machine, on-site service?

I don't know what the undercoating is. It is thick and resilient and may be more than the original layer in places where past repairs are evident. Here are some photos.

[r-mm]

One thing to consider is the the body in the raw isn't very heavy (~650 lbs). You could suspend it from your rafters (2 or 4 point depending on if you want rotation abilities) possibly depending on your garage construction. That's extremely space efficient.

I did this when I was building motorcycles. Of course they only weigh 400-450 lbs, but it was cheaper and more space efficient than having a motorcycle lift and more flexible in terms or orienting the frame. I used a 400 lb Harbor Freight electric winch at each end for height adjustments. $99 each on sale a decade ago.

Intriguing idea. When I consider how to rotate the car 90deg I come back to needing the better part of a rotisserie however. You need rigid mounting to the frame front and rear and the ability to rotate both ends at the same rate.