To make a meniscus mirror I need a precisely-shaped thing that will stay the same shape even at 600C. On Jan 31, I machined out a new piece of wood, sprayed it with polyurethane, and then poured in furnace cement!
...but several days of drying later, I couldn't get the cement out of the mold. It stuck to the wood too well. In attempt #1 I used 3 coats of polyurethane, but in this I only used one. Eventually the wood started warping, so I figured I'd try using a hacksaw to try to cut out the wood, but even that didn't help. Maybe the edges were holding it in place? Nope. The wood was practically bonded to the cement.
So... how can I remove this furnace cement (which cures at high temperatures) from the wood?
I decided to set it on fire.
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