[TheForge] Re: Pickling solutions

[Mike Spencer]

> What is the best solution for pickling? I'm thinking perhaps 10%
> muriatic acid and water?

Muriatic will be pretty fast.  As others have remarked, stuff rusts
almost immediately after you take it out.  Fumes eat your lungs and
tools. 

I've settled on phosphoric acid for almost all iron/steel pickling
purposes.  Relatively non-toxic, no or very little harmful fumes.
No fumes that eat your tools when used indoors.  Leaves a somewhat
protective coating of iron phosphate behind unless you scrub it off.
Disposal is no problem since, in very diluted form, it's great
fertilizer. (Er, assuming you haven't loaded it up with lead, cadmium
or -- unlikely -- weird toxic metals.)

Disadvantages are that you may have to heat it if your shop is chilly
and, if you do heat it (say, with a Kelrod [1] immersion heater) you have
to keep an eye on the concentration because the water diluent
evaporates.

You can also use phosphoric acid instead of bicarbonate in the
electro-cleaning technique that's been discussed here several times.
The acid accelerated the electrical action.  Although phosphoric tends
not to eat into you metal much, it *will* do so in an electro setup.

I recently use phosphoric and a 12v battery charger to clean a very
old axe head that was nearly unrecognizable under its accumulated coat
of rust and embedded dirt.

[1] BTW, a quick google reveals that some -- a very few -- people
    refer to this stuff as "kelrod".  Is there another name for it?
    Stuff like electric stove burners, immersion heaters, some paint
    removers, water heater elements: stainless steel tube of various
    shapes, filled with ceramic and a heater element embedded in the
    ceramic.  Stainless tube may get red hot but isn't itself part of
    the electric circuit.

    I have a couple of paint removers that I stripped and waterproofed
    with hi-temp silicone sealer that I use for immersion heaters in
    phosphoric acid (or anything else :-).  Last time I looked, they
    were no longer available in my hardware store, replaced with a
    hopelessly Mickey-Mouse air-gun type of thing.

- Mike

-- 
   Michael Spencer                  Nova Scotia, Canada       .~. 
                                                           /V\ 
mspencer at tallships.ca                                     /( )\
http://home.tallships.ca/mspencer/                        ^^-^^

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