Re: Investment for lost foam


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Posted by John L. Odom on January 28, 19100 at 07:30:02:

In Reply to: Investment for lost foam posted by Jeff Krueger on January 27, 19100 at 23:23:57:


Because the lost foam process produced a lot of gasses the mold material must be very pouous. Sand is great.

The pouring temperature of aluminum is too high to use with plaster unless the plaster has been thoroughly dried to remove BOTH the mechanical and the chemicaly bonded water. When plaster loses its chemicaly bonded water it loses strength. This is why investments are "grogged" with sand. The drying is accomplished when a wax model is melted out and the investment baked out.

The beauty of lost foam is avoiding all that by simply using sand.

John Odom

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