lost foam: Beware the green foam!

This green foam is great to work with. It carves like sandstone and can be worked with your fingers. Sadly, the green foam does not burn out with molten metal.
(corrections does not burn out with molten zinc see comments)

lost packing peanuts foam horse

would look better with legs.... and a tail. plus something seriously wrong with some proportion that i can't figure out. at the least the front legs are too bulky. point it out in the comment section. I gonna make a new one but not till i figure that out. was my first lost foam with packaging peanut piece.

Lost foam bull #2

Lost foam bull #2

not sure why. much less problems with lost foam bull 1. I think I have it figured out for lost foam bull 3. going to do a "burnout" or washout of the foam with acetone. the other big change is moving away from using any of the more dense pink foam. much harder to burn out. I think that joint to the tail gave me major bubbles.

I have also added a new tag Failure to all the old posts that meet my criteria.

Acetone burnout of lost foam.

I have been looking for a way to make sure that i get a full burnout of my lost foam. I find the gas created in using the metal really makes it hard to get a perfect casting. It was suggested to me by this guy that i try using acetone.

Very happy with the result. I have not poured yet but I have a clean mold. This mold is another lost foam packaging peanut bull but with extra vents. I test all of the vents by putting a piece of paper in them and seeing if it gets wet. I have also determined the exact volume of metal needed by collecting the acetone that filled the mold. Another upgrade is the large mold in an existing bucket instead of simply burying a thinly coated bull in sand. Hopefully this will make a mold blowout impossible.

lost foam figure piece

lost foam figure piece. not a big day because the crucible blew out but got this done first.


Here it is as a bookend with an Ikea clear plastic bookend. Have not attached him yet but might.

Lost foam with packaging peanuts.

The current system:
Packaging peanuts are glued together with hot glue and pour spouts are made out of pink insulation.I have used both drywall mud and plaster and found that plaster is much better for holding the shape.



After the foam is coated with plaster it is buried in play sand and the metal is pour over burning out the foam.






Concerns:
Cleaning the plaster off is a pain. Currently I do it by soaking the piece and working out the plaster with a fine metal tool and a wire brush. I was thinking a pressure washer or sand blaster might work well.
The hot glue sometimes obstructs the profusion of the metal. In this piece one of the rear legs is not getting the metal.

 buy my ingot from Rotometals. also available through Amazon.