Re: Air-set sand

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Posted by bpfink on September 29, 1999 at 07:34:11:

In Reply to: Air-set sand posted by John Odom on September 21, 1999 at 16:57:00:

As an additional comment / question here. There is also a core sand which is composed of a dry sand and a fine powdered rosin. It is generally poured dry into an aluminum mold that is hot and then the rosin melts and binds the sand together that is in contact with the aluminum or heated area. It makes for a kind of solid OR "slush" cast sand molded surface. Detail is very good for a sand cast but I have only seen it used industrially and demonstrated at the International Foundrymen's Conventions. It was used there for exacting core shapes and premade components such as the mold pouring cup assembly or for a cup unit that also had a stainless steel or ceramic screen set in as part to hold back any wayward slag, etc..

Just as a side thought here is the question:

Has anyone ever used it for the whole investment mold in a styrofoam / baked burnout system. I have never tried that but wonder if it might not just work well. The heat source would be from the outside of the metal flask and the investment MIGHT start to set and fuse before the inner styrofoam even melted or altered. In addition since the sand/rosin body would be like a gummy body any expansion of the styrofoam from the warming and heating of it would be compensated for by the flexibility of the sand in the early state.

Once the mold was partially burned out it could be cooled before pouring. A residue of the styrofoam would not be detrimental since this is a sand mold and somewhat able to exhaust gasses also, though certainly not as much as a green sand mold would.

Just a thought and a tad of wondering... it might make a very easy investment to just pour in a bag of dry rosin/sand into a metal flask, tamp it a bit and set into a kiln for burnout.

No fuss, no mess, but maybe a lot of stink or something not being considered here.

bruce paul fink


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