Sealing plaster sculpture from casting plaster, Hydrocal, or POP
babz_from_SF
I've just started sculpting, and finished a couple of soft-ish
scuptures made of casting plaster. People tend to pick them up and
handle them a lot, and I guess pretty soon they'll be worn away, or
grease-stained.
I would love to be able to give these pieces a semi-durable coating
that would allow them to be picked up and handled without wearing away/
grease stains.
In particular, I'm interested in giving them a moderately durable,
transparent low-gloss finish, or whatever I can do that's towards that
end of the spectrum.
Thank you very much for any help/advice,
Barbara
Andrew Werby
"babz_from_SF" <babx....@gmail.com> wrote in message
news:5b0ab9c2-73c0-48b3...@e10g2000prf.googlegroups.com...
[The classic treatment for plaster is shellac. Dilute the first coat heavily
with alcohol (denatured) so it can penetrate. You can build up subsequent
coats with progressively less dilution, if you want more protection or
shine. Shellac tends toward a yellow-orange tinge, which is more evident the
more you put on.
Most paints don't work, because the plaster sucks the solvent out of the
paint before it can form a proper film. I have tried polyurethane varnish,
though, applied similarly to the shellac, and it seemed to work okay on dry
plaster. A waterbased varnish, such as an acrylic medium, might work too,
particularly on a fresh piece, but I haven't tried it.
You say your pieces are "softish" - how did you make them? Plaster works
best if it's all from the same batch. If you've added successive batches to
already set plaster, this will cause the later additions to set poorly,
since the water which is necessary for proper hardening is sucked out before
they can set, resulting in a soft surface. If you're going to work this way,
try soaking the plaster in water before adding more.]
Andrew Werby
www.unitedartworks.com
cjwright1 News Account
To add to what Andrew said you should shellac the plaster. But you can get
a dewaxed clear shellac from Woodworkers Supply. It comes in shellac flakes
that you have to mix with alcohol. This shellac stays clear with the
subsequent coats. It is great for making sure that the white stays a
purerer white not a light golden yellow. Also since the shellac is
dewaxed - other coatings will stick to the top of it unlike regular shellac
which has some wax in it.
"Andrew Werby" <and...@computersculpture.com> wrote in message
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Dan S
"cjwright1 News Account" <cjwr...@verizon.net> wrote:
> dewaxed clear shellac from Woodworkers Supply
I did not know that existed!
i have been using Edison Coating's System 90 II but it's not cheap or
easy to order (it's a 2-parter and one part is hazmat.)
Really Andrew is right, your plaster should not seem soft. People who
mix in too much water also create soft plaster. When you go to add more,
along with wetting it, score the surface.
dan
Gary Waller
shellac sealer, then a white wax shoe polish. The great advantage of shellac
is that the plaster can still be a little wet when you apply it. Red shellac
is easily available, but you may want to tone down the red with
alchol/thinner. Apply a coat, or a couple of coats. Then use a furniture wax
tinted white with pigment or calcium carbonate, or white shoe polish. Get a
rag and carefully rub over the surface. Let it harden, and then buff it and
polish, leaving the white highlights in the undercuts.
It looks a soft warm, red brown, and the highlights make it come alive. I
call it antique finish because this is how the old plaster piece molds
looked - sealed with red shellac, and then larded up to make a mold.
"babz_from_SF" <babx....@gmail.com> wrote in message
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dswest...@gmail.com
diane
SL
http://www.woodweb.com/knowledge_base/Shellac_and_Alcohol.html
http://www.leevalley.com/en/wood/page.aspx?c=&p=20107&cat=1,190,42942
<dswest...@gmail.com> wrote in message
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> diane
This email is free from viruses and malware because avast! Antivirus protection is active.
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lianne....@gmail.com
I am looking for the same solution as Barbara, but I need the plaster to stay white white white - does your dewaxed clear shellac solution still give it an amber/yellow tint or is it just minimized?
Thanks,
Lianne