42761Re: Need advice
- Apr 11, 2013FWIW, US Gypsum also has a plaster specifically formulated for non-ferrous metal casting, they call it simply USG metal casting plaster. The other major North American plaster manufacturer is Georgia Pacific, they also have a line of metal casting plasters.
--- In firstname.lastname@example.org, Dan Brewer <danqualman@...> wrote:
> So here is a link to one supplier.
> The name of the company is US gypsum not US plaster. Brain fart. The way
> that I use it is to take my wax master with sprus and vent attached and
> coat it in Jet dry. Yes the stuff you use in your dish washer. It breaks
> the surface tension on the wax and allows the plaster to stick. I mix a
> little of the plaster up to the consistency of thin pancake batter and
> paint it on. until I have coated the entire master except the top of the
> pouring cup and the top of the vents. . I let that dry a little miz a
> little more up a little thicker and put on another coat. When still wet I
> sprinkle flint sand on the entire piece. Let that dry for a little. Mix up
> some more plaster about 60/40 plaster sand and coat the piece. Let dry. You
> should have coated the piece about 1.4 to 1/2 inch thick by now. Mix up
> some more plaster 50/50 sand and plaster. sprinkle each coat with sand. The
> next coat should be 30/30/30 plaster /sand / and grog. Grog is previously
> fired plaster that has been broken up in to pieces that will fit through a
> #8 sieve. When you have 3/4 to one inch of plaster wrap the piece in small
> chicken wire. This is to keep the mold from breaking up when you fire it.
> Add another inch of plaster , grog, sand to the outside of the mold. The
> top and bottom of the mold should be able to support the mold with out
> tipping over. The top because when you fire it the top will be down so all
> of the wax will leave the mold and the bottom so you can fill the now
> vacated mold with metal. Let dry .for several days in a warm spot. I place
> mine on a blotter board. My blotter board is a 2x2 piece of drywall.
> Place in your kiln and heat at the rate of 100 deg f per hour until the
> melting temp of the wax has been reached. My kiln has a stainless steel
> sink in the bottom that is plumbed out the bottom to get some of the wax
> out of the kiln. I am able to recover some of it but not much. after the
> wax is out around 200 to 275 deg you can ramp up a little faster Fire at
> 2000deg f for 4 to 20 hours depending on size of the piece. Let cool to
> around 400 deg and pour.. Cover the pouring cup and vents with perlite or
> vermiculite and let cool. When the outside of the mold is just hot enough
> to touch sweep off the perlite/ vermiculite and you can remove the
> plaster. Remember that it will be hot. I use a hammer and a water hose to
> remove most of the plaster . Plaster will clog your drain . More clean up
> can be done with a stiff brush or sand blasting.
> For more information look up lost wax casting , ceramic shell casting.
> Dan in Auburn
> Other places to find casting plaster are pottery suppl houses. jewelery
> supply houses. And there are lots of formulas of the casting plaster. This
> is just the one that I have been using.
> On Thu, Apr 11, 2013 at 11:56 AM, Inventor <welfab@...> wrote:
> > **
> > Hey Dan,
> > About a half a dozen links wouldn't hurt....
> > A few to read up about it.
> > A few more as to where to buy it for "20 BUCKS"
> > All I've found was clay and that 'started' at $85/50#.
> > Grandpa Bill
> > --- In email@example.com, Dan Brewer <danqualman@> wrote:
> > >
> > > On of the problems with using POP is that it is hygroscopic meaning that
> > > the material will never release all of the water trapped in its
> > structure.
> > > It actually will draw water out of the atmosphere . I would use a
> > material
> > > that when fired will vitrify and change to a substance that now will
> > reject
> > > water. American plaster makes casting plaster. 50 lbs goes for about
> > > 20USD . There are several others. Plaster of Paris is best left to the
> > > art casting for statues.
> > >
> > > Dan in Auburn
> [Non-text portions of this message have been removed]
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