File puptcrit/puptcrit.0803, message 502


Date: Sat, 29 Mar 2008 14:51:28 -0500
To: puptcrit-AT-puptcrit.org
Subject: Re: [Puptcrit] Industrial type PVA?


The PVA (Poly Vinyl Alcohol) that we use in our shop is a green liquid 
and is used as a mold release or barrier coat in mold making. It is used 
a lot when working with fiberglass. For example, when releasing a 
fiberglass casting  from a fiberglass mold, or as a parting agent for 
the second half of a fiberglass mold or mother mold.

It also comes in quite handy if you use a platinum base silicone against 
a material that would normally inhibit the cure of the silicone 
(platinum base silicone is quite touchy in that respect). The PVA acts 
as a true barrier coat, yet is 'very' thin and will not affect the 
detail of the piece being cast. You can brush PVA on or apply with an 
airbrush. The nice part is, when  you are finished, the dry PVA wipes 
away and dissolves with just water.

 It's an easy material to use for this type of application. This type of 
Poly Vinyl Alcohol is not really an adhesive, and has no tear strength 
even if it had strong adhesive qualities. A little goes a long ways. 
I've had a 1 gallon bottle for about 15 years, and there's still a third 
of it  remaining. I wouldn't be without it myself, but I work a lot with 
silicone, urethane and fiberglass (both polyester and epoxy).

Cheers,

Mike Brose
http://www.puppetsandprops.com

Steve Millward wrote:
> I have only read about it.  It is used in the bookbinding industry.  The
> Material safety data sheet says it can be a skin irritant.  For the powdered
> form  you would want to use a respirator.  Write to the Celanese corporation
> and ask for a sample.
>
> Steve
>   

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