Update on my restoration - Dipping process notes

Some of you will remember my post many moons ago requesting opinions and experience with "dipping" the entire car in caustic solution to strip paint, dirt, rust, and undercoating. You all responded with resounding "DON'T DO IT" assertions and horror stories. I quickly made plans to pull my car out of the dipper line where it had been for months, and take it off to a more friendly "plastic media blast" service.

So I called the dipper and they say "Hey funny you called, we finally got your car in the bath."

Doh.

Well, I had to do some research on how to salvage the situation, and spoke to several experts on the subject. The problem is, the alkaline solution stays in some of the hard-to-reach seams and channels. Months or years later, it forms a salt and comes through paint, weakening the metal/renewing corrosion, and ruining the restoration. My findings were as follow-
1. Split all seams of concern and thoroughly clean.
2. Use POR-15 and epoxy primer to "seal" all other areas of concern. These paints form a ceramic-like, non-porous finish that is not permeable by oxygen. The minute amounts of leftover solution are never allowed to react. One guy I spoke to said he has dipped entire cars into epoxy primer after dipping, and has had no problems since with any of them.

We've been taking a mix of the two approaches to preventing these problems. We've gone into what areas of the box sections we can to clean them up. Some salts are already coming out of some of the seams, which is actually a good thing. We know what to look for and clean up. We are going to hit every area of this car with POR-15 or epoxy and hope for the best. I'm confident about our work so far.

In other news, I've gathered together most of my suspension components. Adjustable sway bars, Bilstein sports, front monoballs, poly bushings all around, turbo tie rods, adjustable spring plates. I will be ordering stiff torsion bars and a front strut bar soon. So the restoration marches on and the bank account atrophies!

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Dave
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http://members.nbci.com/dtwinters/garage/

Wow! I hadn't seen your site before. Very impressive. When it's done (sometime before your grandchildren are born, maybe?) you're going to have a car that you know every square centimeter of! No one will enjoy a car like you will enjoy that one. What a great project!

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Jack Olsen
1973 911 T (3.6) sunroof coupe

Dave,
I did the dipping thing on my '76 Carrera. It's been 2 1/2 years now and nothing weird showed up so far. I think there are two things that will help. The first is to let that baby dry completely. In yours you're lucky that the rust holes let the whole car ventilate; mine stood in a dry ventilated room for 6 months before work began on it. The second thing that will help is cavity wax. I put this stuff in every hole, nook and cranny. It took me tha best part of a day with the bodyshop installation, i.e. LONG nozzle extension. I let the goop drip off for three weeks before doing anything else on the tub.
As I said, I'm still waiting for anything weird to come up. A thing of interest is that the company that dipped the tub for me spent more time rinsing the tub than dipping it.
Hope this helps, GeorgeK

oops..

[This message has been edited by GeorgeK (edited 12-13-2000).]

I agree with George!

Every product forming a stiff sealant will trap bubbles, unprotected areas, even condensating water. You are creating rust spots on purpose.
Cavity wax is the best you can do, esp. the 2 stage products with a very liquid "primer" wax and a more stiff but flexible coating wax.
Even if you have large temp differences, this wax will flow into any open cavity and re-seal it. It is also flexible enough to withstand all body movements, expansions and contrations over douzends of years, where normal products just produce cracks leaving water in.
The only disadvantage is, that sometimes in hot summer, you will find spots of wax dripping out of your car. But this is only a sign that the theory works. (And you clean your car anyway, eh?).

Jens