2 comments on “Lost-Foam Casting: A Primer

  1. Hello-
    I am doing some lost foam casting, where the molten aluminum is cast around wood. I have been having trouble with the gases from the melting foam causing a lot of bubbling and the eventual failure of the casting. I know it is a venting issue, and I am going to try the drinking straw method. Is the straw simply glued to the surface of the foam? Or is there a hole in the foam where the straw is attached? I would guess that a drilled hole under the straw would allow gas to escape earlier in the pour… Thanks very much for the blog posting and any help you can offer.

    • Hi Erin, sorry I am seeing this so late…The straw is glued around its perimeter, no hole drilled under…that has never been necessary for me even when pouring a 20 lb piece that needed about 8 straws if I remember correctly. I spaced them evenly and glued them at intersections/joints in the casting because I figured if there was any cross-flow of molten metal through those joints, it would create a lot of churn that would force gases out faster. I’ll be interested to see how it turns out!

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