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Step 4Build hearth
The Popular Science article I read mentioned using a casserole dish for the hearth, but then went on to say that the glass top of the dish cracked due to thermal stress after being heated then removed from the microwave. Not wanting to have shattered glass in my face I opted to skip this step and go right for brick as the hearth.
Knowing that I would be reaching tempertures of 500°C (900°F), I wanted something that could handle the heat stress and fracture if it failed and not splinter. I chose brick. There's a specific dense brick used in fireplaces called fire-brick that would have been ideal, however I used think regular bricks and no fractures occurred in over 40 minutes of heating. I also (erroneously) added an additional layer or insulation to the inside of the brick to try and create more heat in the hearth. Do not do this! Brick on it's own will suffice.
Stack your bricks into a simple house-like configuration. Leaving anough room in the middle to have your silicon-carbide slab to sit on teh base of your brick-house with the stainless steel crucible on top. Lay bricks over roof of brick house.
Knowing that I would be reaching tempertures of 500°C (900°F), I wanted something that could handle the heat stress and fracture if it failed and not splinter. I chose brick. There's a specific dense brick used in fireplaces called fire-brick that would have been ideal, however I used think regular bricks and no fractures occurred in over 40 minutes of heating. I also (erroneously) added an additional layer or insulation to the inside of the brick to try and create more heat in the hearth. Do not do this! Brick on it's own will suffice.
Stack your bricks into a simple house-like configuration. Leaving anough room in the middle to have your silicon-carbide slab to sit on teh base of your brick-house with the stainless steel crucible on top. Lay bricks over roof of brick house.
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What are the white bricks in the picture? Are these the slabs of insulation that you are telling us NOT to use? There seems to be a disconnect between the written and the visual instructions that is a bit alarming! I sure wouldn't want to make a mistake with an instructable like this. Could you clarify?
The instructions are clear and I quote "DO NOT DO THIS!"