Frank,
The acid you *should* use to treat rust is phosphoric acid, not muriatic
acid. Muriatic acid is Hydrochloric acid.
Muriatic acid dissolves steel and rust at approximately the same rate
whereas phosphoric acid eats steel at a much slower rate than rust. Hence
after treating with phosphoric acid you can dissolve the rust without
affecting
the metal much at all whereas with muriatic, you might not have much
bodywork left by the time the rust is gone!
An additional disadvantage of muriatic acid is that it cause hydrogen
embrittlement making the structure more prone to cracking and failed
welds. This apparently cannot be reversed.
With phosphoric acid, bare metal will be left with a protective oxide layer
and will not rust if kept out of the weather for a reasonable time. If you
use
mechanical means of rust removal you have to prime *immediately*
Dulux (aka ICI), and Wattyl (two large automotive paint manufacturers
here in Australia) both have commercial phosphoric acid treatments. I have
used Wattyl's and was extremely impressed. I used repeated treatments
and used a wire brush wheel to remove the deposits between each treatment.
I continued until I no longer got any heavy black deposits. I have not
had the rust return.
Mike
-----Original Message-----
From: Frank Clarici <spritenut@Exit109.com>
To: Ajhsys@aol.com <Ajhsys@aol.com>
Cc: Lancer7676@aol.com <Lancer7676@aol.com>; spridgets@autox.team.net
<spridgets@autox.team.net>
Date: Tuesday, 19 January 1999 12:12
Subject: Re: Fiberglass Floorboards (was Re: DIY Carpet + DPO)
>
>> For more, go to: POR-15 - http://www.por15.com
>> Eastwood - http://shop.eastwoodco.com
>>
>> YMMV, and make sure you remove any loose rust, dirt, grease and oil
before
>> applying ANYTHING!
>>
>> List?
>
>POR 15 is just another rust cover up. Been there and followed the
>instructions to the letter.
>Then the floor pan fell out in a rain storm and made like a funnel
>scooping up water and funneling it into the car. It took about 18 months
>but the whole front footwell actually fell out. But is was well painted
>with POR 15 and still all in one piece instead of a bunch of rust chips.
>If you can not paint the inside of the rust it will creep to the edges
>of the metal where it continues to eat away untill there is no more
>metal to eat then the floor falls out.
>At least it did on me.
>Now I cut all rust out and replace the metal with US Steel.
>Other rust killers which work on MINOR rust that turn it into a black
>surface like "Rust Mort", "Extend", or others do work but not on
>cancerous rust.
>Most of the others contain Muriatic acid (I think) A cheaper way to go
>is to use muriatic acid heavily diluted and outside. Do not use it in
>the garage. wash the metal with the acid, rinse well 4 times, then rinse
>again a few more times, follow with a good metal prep solution and etch
>or epoxy prime immediatly.
>Fiberglass will work great but again only on clean bare shiney metal.
>It will not last on rusty metal. The rust keeps going and going.
>I have taken apart a lot of botched up Spridgets and saw some really
>crude repairs, I have also seen some good repairs but all the repairs
>made over rust did not hold.
>The "surface rust" people talk about when they are selling you a car is
>on the outside surface but it started on the inside of the panel.
>If the rust looks like bubbles, it is cancer. On the rare occasion it
>may truly be surface rust, it may be but it started due to a chip or
>scratch in the paint.
>If you can poke a thin screw driver thru the bubbles, cut it out and
>replace the metal.
>
>Learn from my mistakes, I tried all the cover ups and then had to
>replace the metal after the finished paint job.
>
>Rust never sleeps, even when covered up it is still awake.
>--
>Frank Clarici
>Toms River, NJ
>Lots of LBCs
>http://www.exit109.com/~spritenut
>
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