From: John Murray 
To: Russell Jocoy , bobmay{at}nethere.com, atm{at}shore.net
Reply-To: John Murray 


Russell,
        I've been doing the agitation via orbital sander for a few tools now
with
no problem. I took the advice from the USG site before I started doing
this. The photo and data sheet for Hydrocal 105 (which is what I am using)
has under the heading "Pouring" the following advice.
        To prevent air entrapment and provide a uniform smooth surface, careful
pouring of the slurry is necessary. Agitation of the filled mould is a
further step used to prevent air at or near the surface of the cast piece.

        As I say, the orbital sander floats the air bubbles out and fills any
voids
easily without making a mess. If you get caught when the plaster starts to
go off you can give yourself some more time to get it right. The thing
though, is that after the pour is done and while the plaster is still
fluid, a quick burst of the sander usually prevents you from getting caught
out in the first place thus avoiding the need to do the agitation after it
has started to go off.

Cheers

John Murray
Whyalla
South Australia
Check our web page at http://astronomy.sa86net.com ATM and M-O-M stuff.
Latest Ronchigrams only at http://www.users.bigpond.com/imasloth/


> >
> ("atm{at}shore.net")
>
>     Bob,    I keep agreeing with your statements and it may sound
> like a yes
> man but you are right  on.
> These quick set "concrete or plaster" mixtures are not cement in
> the laymans
> terms. These mixtures
> are closer to epoxies in reality. Most all quick set plasters or cements
> will give instructions as to NOT
> add water after the process has begun, and also Not to agitate once the
> hardening has started.
>     To all on the list that are not used to using dental plaster,
> Hydrostone, or hydraulic cement,  mix
> a small portion and see what properties are and how quick they
> set. You can
> set up your process
> accordingly in quick steps, just as the mixture sets up in quick
> steps.....
>   These  mixtures will NOT
> wait for you (if you have ever tried to BONDO a fender you can
> understand)
> Oh, my bad, fenders
> don't dent anymore, they bounce back out.   Here I go again.... Russ J.
> ("atm{at}shore.net")
>
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