I am a chemist so I will try to clear up a few comments here. (Though I
know little about treating metal for galvanizing.) First TSP is not a
soap with a polar end and a non-polar end. It is just tri-sodium
phosphate, Na3PO4. This is the basic form of phosphoric acid, H3PO4. So
TSP is a base and can consume three equivalents of HCL, which would
produce H3PO4 and 3NaCl. This resulting solution would be quite acidic.
The key to neutralizing the HCl would be to use excess TSP so the
solution always remains somewhat basic. Sodium hydroxide, NaOH, will do
the same thing, but it is more basic and dangerous than the TSP. In any
case expect the solution to give off heat as you neutralize the acid.
So add the acid slowly to the base, while stirring the basic solution.
This should minimize any heat build-up.

Good-luck,

John

In article , jim rozen
wrote:

In article , Harold & Susan Vordos says...

I"m no chemistry wizard, but my years of precious metal refining taught me a
few things about hydrochloric acid and metals. I think I'd use a dilute
solution of hydrochloric to clean the steel parts you want to galvanize,
then neutralize the parts with sodium hydroxide (lye). That will prevent
the instantaneous rusting you would otherwise get. I used to run a small
ball mill. So long as I kept the interior basic (9 pH or higher), there was
no rusting.

I think this is pretty good advice. The base will neutralize
any acidity. The TSP is not really a base, IIRC it's like
most detergents, being a large molecule that is polar at
one end, and non-polar at the other end. So the polar
end grabs onto the water, and the non-polar end grabs
the oil or grease.

I also suspect that simply rinsing the parts well, and
using a mild base like baking soda will be enough, so
he would not have to deal with caustic NaOH solutions.

Jim

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