Subject: Re: Lost Wax Casting

From: [email-masked] (Carl Mork)
Date: Sun, 16 Oct 1994 06:12:00 GMT

-=> Quoting [email-masked] to All <=-

 Ro> 2. I also have heard about needing to shake or vibrate the flask as
 Ro> the investment hardens. Is this important, useful, and how violently
 Ro> shaken does it need to be? 

     I don't know about any ceramic coating,but it may something my teachers
 never mentioned.  It may have something to do with the practice of coating a
 wax model with a thin solution of investment plaster before puttin in the
 the investment.  This helps reduce chances of bubbles staying on the surface
 of the mold.

     As far shaking the investment, it is very important.  As you mix the 
     investment, bubbles form and these have to be gotten out or you lose 
     the whole thing.  People who do casting for a living usually buy a 
     vibrating surface to do it for them.  You shouldn't do it too violently
     as that could break the wax model or the sprues, but firm enough to knock
     the bubbles loose and send them to the surface.

     Hope this is of some help.
     [email-masked]

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From: Bruce Olson <[email-masked]>
Date: Mon, 17 Oct 94 00:12:17 -0500

The wash is just a thin coat of investment to prevent air bubbles from forming
on the surface when the investment in poured in the flask.  The vibrating of
the flask after the investment is poured in is another
attempt to remove air trapped on or under the wax pattern.  A vacuum is
frequently used (the entire flask is placed in a vacuum)to remove air bubbles.
I use both the vacuum and a gentle pounding with the hand on the vacuum
machine to remove air bubbles.  The investment should be evacuated before
it is poured into the flask or it will bubble up much like a loaf of bread
when it is baked and run over the edges of the flask. Good luck.