Styrofoam / Polystyrene release agent
franwood
me create nameplates and logo's with our CNC hotwire machine. We use
polystyrene to create the molds.
The first small attempt work well and the plaster released OK, the
second attempt was a little more complicated and the polystyrene stuck
to the plaster and had to be picked off.
I have heard that vegetable oil can be used as a release agent, does
anyone have any product to recommend.
TIA
Fran
Rockhewer
try stuck. Here are several links that will hopefully help. I've heard that
the vegetable oil and mineral oil mix is good for latex molds. Just plain
old Murphy's Oil Soap is a good release agent also for plaster. Good luck.
http://www.cresset.com/rabrochu.htm
http://www.cresset.com/specs/880voc.htm
http://www.artstuf.com/surfacetreatments.html
"franwood" <fran...@eircom.net> wrote in message
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franwood
thanks for the links and reply.
I'm sorry l didn't make myself clear. The second attempt was with a
more complex mold but was it was new. We imagine that unless we were
asked to make a large quantity it will be easier to make a polystyrene
mold for each cast. We know that polystyrene isn't an ideal material
for large runs.
Is "Murphy's oil soap" a liquid, being based in Ireland you would think
l should know of it but unfortunately l don't , so l presume it's a US
based product.
Rockhewer
My apologies also. Yes Murphy's Oil Soap is a cleaning product for wood.
Just a liquid soap with very high oil content. You might have a similar
product available to you there. I don't have any experience with
polystyrene as mold material. I make plaster models, then coat them with a
petroleum jelly dissolved in a carrier such as painters naphtha or xylene to
use as a separator. However that may damage the polystyrene. The main
problem I see for you is having no buildup of the separator on the mold.
Here's another link I have that may help.
http://www.plastermaster.com/usg/plaster201.htm
"franwood" <fran...@eircom.net> wrote in message
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franwood
I think l will try the "petroleum jelly" idea and see how it works. I
see from your link l will have a few other products to try as well.
Cheers
Fran
Andrew Werby
to remove from the finished product. If you plan on painting it later, this
can come back to haunt you. Petroleum jelly is among the worst in this
regard. This is why most plaster casters prefer soaps to oils as release
agents. Besides Murphy's Oil Soap, you might try a dishwashing liquid (not
the type used in automatic dishwashers, but the regular hand-washing type).
I suppose polystyrene foam can be used for one-off or short-run molds if
attention is paid to draft. Try to keep all verticals at least 3 degrees in
from perpendicular; this will help a lot in releasing your castings. If the
foam has a lot of texture to it, this can impede release too; you might
think about a filler if this is a problem. There are some coatings (eg
Styrocoat) that will smooth out the surface of sytrofoam, making it easier
to release.
For longer runs, look into making silicone rubber molds from your
polystyrene positive forms; these release plaster quite well with no mold
release agents being necessary. Here's a source of supplies:
http://www.farwestmaterials.com/newpro.htm .]
Andrew Werby
www.unitedartworks.com
franwood
some stage we will look at painting the finished cast. Thanks for the
info regarding the cons of using vaseline.
We could cut a tapered mold but it would be very time consuming
therefore out waying the advantage of using the machine. We realise
that foam isn't an ideal material but it is quick and cheap to create
the nameplates etc.
The texture might be an issue, we thought that we could use a water
based auto filler primer. We have yet to try this idea.
As for the longer runs the plaster molding company are familiar with
rubber molds as they use them and have created their own designs.
It's nice to get further round the learning curve without falling at
these potential hurdles.
Thanks for the info and the link,
Gary Waller
wet it out with an epoxy resin like "west systems" or better - use their
filler/thickening ingredients. You'll end up with a thin, tough shell. -
easily released, unless it gets too hot (then you use high heat epoxies)
Then travel to Europe, the Middle East (especially Morocco), India, etc
- and see that the cnc look kills plasterwork - that the beautiful and
addictive stufff in the world has an organic character - be aware of the
organics if you want to succeed with the aethestics. A computer could
never recreate a rose garden.
CNC remains a dream of the (Star Trek) Borgs and (Dr. Who) Daleks.