"Ken Grunke" wrote in message
...
Harold and Susan Vordos wrote:
"Ken Grunke" wrote in message
...

Rex B wrote:

Electrolytic Rust Removal - Bought a Craftsman 618 parts lathe that's a
prime candidate for rust removal. I went to HD and a supermarket in
search of washing soda, sodium carbonate, but all I got was quizzical
facial expressions from the help. So ....where do you get that stuff?

Muriatic acid will dissolve the rust without hurting the steel.


Sorry, Ken, that's not true. If you leave steel in muriatic long
enough,
it's gone, assuming you don't consume the acid first. Muriatic acid
will
also attack particular spots on steel and eat them faster, assuming you
leave your pieces in long enough. It's a lot smarter to use phosphoric
acid
if you're going to use an acid at all.

In the case of HCL (muriatic) it doesn't really matter if you pour the
water
into the acid, but it's a bad habit to acquire, especially if you work
with
sulfuric acid. I've seen it empty an evaporating dish when it finally
decided to mix with the water.

This is not a strong argument for using the stuff, Harold--but of course
you wouldn't leave a piece of steel in the acid longer than needed to
dissolve the rust.
I tried it today, just to make sure I wasn't a brick or two short of a
load. A smidgen of straight-from-the-jug muriatic in a plastic cup
dissolved a heavy coat of rust on a scrap piece of steel in 2-3 minutes,
leaving a dull gray, but very clean surface.
I'm definitely interested in alternatives, having some rust problems of
my own in my shop. I just happened to have a partial gallon of muriatic
around, and it's come in handy for small rust removal jobs.

I use electrolytic rust removal, (Rex, "washing soda" is Arm & Hammer All
Natural Super Washing Soda," 'comes in a yellow 55-oz. box, in the laundry
detergent section of most large supermarkets), muriatic acid, glacial acetic
acid, or phosphoric acid, as appropriate. I've become a connoisseur of rust
and filth g). I haven't tried the salt-and-vinegar approach.

I like the eletrolytic method. It leaves some black crud that brushes off
easily with a stainless brush. So does phosphoric acid (although the black
crud left by phosphoric, when it's used on thick rust, can be much harder to
remove), which, according to the experts, does not attack the base metal.
It's used by automobile body restorers for that reason. The black crud is
another iron oxide, which the removal process converts from red rust, both
of which I'll leave to the experts to describe.

Glacial acetic is something I picked up from an old-tool restorer. I've
replaced it with electolytic, which works faster and better.

Muriatic is the fastest but it supposedly penetrates fine tracks left by the
rust, and it's also alleged to leave NaCl (salt) in the pores if you try to
neutralize it with baking soda. I haven't had that problem but I generally
just rinse it with water these days, to avoid it. Muriatic does not leave
the black crud. It is said to attack the base metal to a slight degree
(nitric acid being the one that attacks it to an extreme degree).

For the elctrolytic method, I've used both the tank method and the brush
method. I like the brush method better. It's described in the dropbox
somewhere -- maybe someone can help you find it.

For the tank method I use just a dilute solution of washing soda. For the
brush method I use the more complex formula described in the dropbox. I
don't know if it's necessary -- I haven't tried the simple washing soda
solution with the brush method -- but I will some day soon.

My power supply is a 4-amp automobile battery charger. It works great, both
for the tank and for the brush. Sometimes I switch it to 6V to get the
amperage down to where I want it.

Happy de-rusting.

--
Ed Huntress