[Clayart] Parting Agent

[John Rodgers]

In my years of experience in doing mold work, I have used just about
everything as a release agent. The very best that I have ever found was
tincture of green soap cut  50% with water. Get it by the gallon at Amazon.
It is not cheap, but its better than any thing else I ever used. In other
words, as example, 1 pint of water added to  1 pint of soap. Apply with a
real sponge,  work to a foam, allow to nearly dry, brush with a clean dry
brush made of white hog bristle ( a finer type artist paint brush sometimes
called china bristle) until all evidene of wetness is gone. Then apply a
second coat, repeat the process. Then apply a third coat. Drip a few drops
of water  on the surface. If the water stands as though on wax, it's ready.
If not, do it all one more time.

Ideally the pieces should be parted when plaster or cement is at its peak
heat, because the soap will be softest from the heat at that time. And
excess water will be squeezed out also helping to soften the soap.

If using clay to get the mold shape, no release is needed if plaster or
cement is used, as the clay will come out with a good washing.

Finally, clean your brushes with alcohol, then was in clean water.  Dip in
alchol and beat dry.

John

On Wed, May 9, 2018, 20:34 Snail Scott <claywork at flying-snail.com> wrote:

>
> > On May 9, 2018, at 9:13 AM, Bill Karaffa <bkaraffa at centurytel.net>
> wrote:
> >
> > I am casting some burner ports using Mizzou castable and was wondering
> about
> > parting agents. Last time I cast them was long ago. I think I used either
> > WD-40 or dish detergent…
>
> You didn’t specify what you were using for the mold, but I’ll assume wood
> or brick. In any case, neither WD-40 nor detergent is a good parting agent
> for much of anything. WD-40 will do for very smooth, impervious surfaces
> that just need a little grease - cooking spray will work about the same or
> better, actually. Vaseline will do, but it’s icky to work with and tends to
> be streaky for applications requiring good surface quality (though that’s
> not really relevant here). For this, or anything with even a little
> porosity, I’d use soap.
>
> I like plain ol’ Murphy’s Oil Soap for most mold release purposes. I’ve
> used expensive purpose-made mold-release soaps, but Murphy’s does almost as
> well for a fraction of the price. For a not-too-refined application like
> castable refractory, it’s entirely sufficient. Plus, you can buy it locally
> almost anywhere, in the cleaning products aisle at Wal-Mart.  Apply one
> layer, let it dry, then apply another and let it dry, too, to build up a
> good coating. Buff if you like, though I doubt it’s worth the effort for
> burner ports!
>
> Note that dish detergent is NOT soap. It’s a detergent - an entirely
> different chemical. So-called ‘soft soap’ and liquid hand soap are not
> actual soap, either: they are detergents, too. You gotta have an actual
> stearate for it to be useful as a mold release. Murphy’s is about the only
> actual liquid soap out there nowadays.
>
> Snail Scott
> claywork at flying-snail.com
> www.snailscott.com
>
>
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