SV: Rust conversion


Bo Strander

A comment about the method of filling hided areas with polyurethane foam or
any other foam.
In europe some 30 years agoo AlfaRomeo produced a car called Alfasud. In
order to get a quiet and smoth-running car they filled, among other areas,
the frontscreen frame, called the A-frame with some kind of foam-material.
This showed to be a catastrofy some years later....Thousands and thousands
of car was totally damadged by corrosion in the areas where the foam was
used. On the outside they sometimes locked nice but the roof where sometimes
kept in place only by the C-frames and the paint!!
Just a comment from other side of the pool....
Bo the swede
-----Ursprungligt meddelande-----
Fr?n: []
Skickat: den 14 november 2003 01:26
?mne: Re: [amphicar-lovers] Rust conversion

In my experience, both Phosphoric Acid and Muriatic acid work well, though
differently. For 30 years, I have bought a product called "OSPHO" which is
solution of Phosphoric acid. I debride (wire brush, or scrape heavy rust
then using a spray bottle, apply Phosphoric acid liberally. It is
relatively safe
to handle, much like Muriactic acid. It is definitely more expensive than
muriatic acid, but does a different sort of job. I have bought it by the
and a gallon will last me nowadays several years, though once upon a time
had a steel boat (significantly larger than an amphicar) and I used more.
Spraying the Ospho on liberally, it is then allowed to set and dry which
probably take 24 hours or possibly longer if it is not exposed to a lot of
ventilation to allow it to act on the rust and chemically convert it. A
chalky white
residue will end up on the previously rusted parts, and as the distributor
the product will say in print, it converts the Iron Oxide (which is the
rust) to
Iron Phosphate. I would then recommend brushing off the white powdery
and proceed to paint it with a good quality material which will adhere
directly to the rust free metal. If it is not coated with a suitable
paint or epoxy
primer, etc., it will begin the re-rusting process again if subjected to
moisture after a period of time.
The other alternative, as Ed suggested, is to immerse the item in
Muriatic acid for a few minutes - probably 10 -20, after having debrided
it of
consequential rust as with the Ospho treatment above. Once the rust has
been disolved off, the parts should be washed thoroughly, ideally in a
solution of baking powder to neutralize the acid, then immediately blown
completely dry, as rusting will try to start immediately. This is fresh
rust free metal
and should be primed or painted right away.
On my rear quarter panels 3-1/2 years ago, I ground away the infected
areas which were not huge, but perhaps 1 x 6 inches on right and left. I
applied the Ospho, waited a day or two, wire brushed and scraped as
completely as
possible, then filled with Polyurethane foam in place foam and a competent
body man completed the job and painted the quarters. I expected to have
years of peace. Not so. Don't bother with this approach. I conclude that
Polyurethane, though sticky as the devil initially, does not tightly
adhere to the
metal and moisture invades and now I'm set to repair both quarters again.
They are not bad - just way too unsightly for my taste and it will only
One of the members suggested putting in an access port to spray in heavy
undercoating to adhere to the "de-rusted" metal inside these lower
quarters and
this may be a good idea. Anyway, as one can guess, I am disgusted after
what I thought to be a good job that the corrosion bubbles have now
This is a great subject for opinions, past experiences and suggestions.
Vic "Splash" Nelson near Daytona with the Aqua 67 Split Personality

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