Subject: Re: Sand Casting Question

From: [email-masked] (Kurt Schaefer)
Date: 4 Dec 1996 19:35:40 GMT

> The problem arrises with the wooden models.  Even though the model 
> is liberally coated with the talc, we still have a problem with the 
> sand clinging to the models. This is especially true with with D
> rings and other closed shapes.  We would preferr to use basswood for
> the models, because it is easy to carve.  Maybe this is the problem?
>  Do we need to paint the models?  Is wood a poor choice?

I use wood to make patterns all the time.  I do the fillet work using
Bondo.  Then I seal the wood with a couple of coats of quick drying 
polyurethane varnish.  Works a treat.

   Good luck!
          -Kurt

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From: [email-masked] (Bruce E. Ferguson)
Date: 4 Dec 1996 13:59:33 GMT

We at the George Ranch have begun experimenting with bronze casting.  We 
are heating the bronze in a silicon carbide crucible in the forge and 
have encountered little problem getting the bronze to melt.  We are sand 
casting the bronze with a commercially available casting sand.  It is 
red and oily.  We are using talc as the parting compound or release and 
have had good luck with metal and plastic models.  The problem arrises 
with the wooden models.  Even though the model is liberally coated with 
the talc, we still have a problem with the sand clinging to the models. 
This is especially true with with D rings and other closed shapes.  We 
would preferr to use basswood for the models, because it is easy to 
carve.  Maybe this is the problem?  Do we need to paint the models?  Is 
wood a poor choice?

Thanks,
Bruce

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From: [email-masked]
Date: 4 Dec 1996 22:14:53 GMT

For wood patterns in oil-bonded sand, I heavily wax the pattern (three or
four coats, well buffed) and use regular kitchen-type corn starch as the
parting compound. This works well, even on deep cavities.
--
Winston W. Harness
http://ourworld.compuserve.com/homepages/brnzcaster/
--

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From: [email-masked] (Georgie Stanford)
Date: 5 Dec 1996 23:20:19 GMT

Kurt Schaefer ([email-masked]) wrote:
: 
: > The problem arrises with the wooden models.  Even though the model 
: > is liberally coated with the talc, we still have a problem with the 
: > sand clinging to the models. This is especially true with with D
: > rings and other closed shapes.  We would preferr to use basswood for
: > the models, because it is easy to carve.  Maybe this is the problem?
: >  Do we need to paint the models?  Is wood a poor choice?
: 
: I use wood to make patterns all the time.  I do the fillet work using
: Bondo.  Then I seal the wood with a couple of coats of quick drying 
: polyurethane varnish.  Works a treat.
: 
:    Good luck!
:           -Kurt
I use tung oil and then when it's dry smooth it first with #600 emery 
paper then burnish with a steel burnisher to harden the surface and fill 
in any pores that might be left. I wonder if he keeps his sand too moist or 
doesn't tap enough before he removes the model?

Georgie