bbh03

I know this has been covered a little before, but I'm looking for some clarification on a couple issues.

The car in question is a 1978sc with cage installed. Flash rust on the cage.

The options would be regular sand blasting, soda blasting and dipping. Sand is out due to the damage done to the body medal.

Dipping looks attractive because it removes everything. However, I spoke to someone there and they told me (when asked) that it will remove the galvanization on the metal. This is contrary to what is mentioned in some older threads. This is the same place in Allentown, PA. The other downside is the need to transport immediately for priming. I've also read some people advising against dipping if there is a cage installed in case some of the solution gets inside (although it shouldn't be able to).

The option I like best right now is a local place that will blast with sodium bicarbonate. Unlike sand, it is said to remove no metal and is kinder to the body work. As a side note, it is envireonmentaly friendly too. One of the best things about this place is that they will prime right on site - a huge plus logistically. The cost of th stripping alone - inside, outside, underneath, etc is comparable to the dipping process. The priming is of course extra.

Oh, and the wait right now for dipping is at least a month vs a week or two for the blasting.

Can anyone comment on the pros/cons here? Anyone know something more about this soda blasting you can share?

Also, what exactly is the need for seam welding after either or both of these processes? Is it only for sealing, or also for rigidity?

Thanks all!

Geoffrey

If the car has a cage, you will more than likely get solution into the inside of the cage. It is very difficult to make a cage 100% airtight. The dipping process (mine was done at Allentown) does not remove the galvanizing.

I would have the chassis media blasted. There are any number of different types of media that can be used that will not deform the metal. Mine was media blasted after dipping since it took so long for me to prepare the chassis.

No worries, it works out fine.

chrisp

will soda blasting take off undercoating?

You might need to sand blast the undercarriage and soda blast the painted surfaces.

You also have the option of other media like walnut shells, corn husks, glass beads, etc. These offer different levels of coarseness and time to strip the surface.

Gary R.

I don't believe any type of blasting is efficient on undercoating, either it has to be heated/scraped or dissolved. Even the coarsest grit takes forever to get UC off..

srf506

Most sanctioning bodies require a small hole be drilled at some point of the roll cage so it can be checked for compliance with the gauge tubing specified for that class of car. By default, the liquid will find its way into any little gap or crack. SOda or "media" blasting that uses crushed walnut shels or plastic pellets is also a viable alternative.

AndyT

I habe heard walnut shell blasting is a good alternative to sand. I'm serious BTW.
What about glass beads ?

cooleyjb

We use walnut shells at my dad's shop. Works great for most things. Plus it smells nice. It does take a while to clean off some things.

Tom W

Geoffrey: I got the impression from your posts that you did not hand strip/scrape the undercoating prior to dipping and that dipping alone was effective if removal of the undercoating. True?

Geoffrey

My car was baked in an oven then acid dipped at the same location. Another alternative that I would probably choose if I had to do it over again would be to have it baked and then blasted which accomplishes the same thing but does not "wet" the chassis. I don't know what they use for blasting, but the cars I've seen come back without any metal compromized. The blasting will take off the galvanizing, the acid dipping does not...at least my experience shows that.

OR

I would look for a place that dipped the car and then immediately powdercoated it but the only place like that was down south, possibly Autometrics (probably subbed out), I can't remember.

Tom W

I'm in CA and it's a question of finding a place to blast or dip and the cost of doing that (stripping the car down, doing the work and shipping the tub back-and-forth) versus hiring some kid to use a heat gun and putty knife to get the easy stuff at a lot less cost is one consideration (in addition to the question here of blast vs. dip).

RedlineMan

Hey;

As Geoffrey alludes to, the only thing that really gets to the schutz is baking or dipping. Any media that will get the undercoat would harm the metal, and it would be a real dance to keep from doing that. It takes freighteningly little to over heat the sheetmetal and cause warpage.

Plastic media is great for most paint, at least factory finishes. It struggles a bit with multiple layers of filler and repaint (like anything does) , but it will not harm metal, glass, trim, etc. Plastic is what they use to strip fleet vehicles. The don't even mask the glass or anything.

Palmer Clingman

Hi if you could get the car to Ma we do ultra hi pressure water blasting 40000.00 psi and have done
many cars A 911 takes about 4 hours for inside and out of a tub it removes the undercoating and
sound deadening easly and leves the galv. There may be some people in your area that do it also
Thanks Palmer

bbh03

I guess dipping is out due to the cage anyway. I removed the fenders today and saw a pretty thick layer of undercoating and wondered if the soda could remove that - I guess we'll see! I may have to scrap the majority first and let the media get the residue.

Any comment on the seam welding? Should I have this done or just go with some seam sealer and be done with it?

I haven't seen anyone near here doing HP water blasting. Wouldn't a problem would be getting the thing dry in the crevices?

Incidently, the left fender has severe rust damage right at the mounting seam. The right side was in much better shape. Might have to go to glass!

Geoffrey

Seam welding is actually "stitch welding" where you weld a bead for 25mm then a space for 25mm. It strengthens the chassis over the production spot welds. It does not take the place of seam sealer.

bbh03

got it, thanks. I've seen people allude to a manual for this. What can that be found?