Building a glass box

Investment core

Plastic box with removable sides will contain the plaster/silica mixture that will form the investment core.

Investment core

The plaster/silica investment core is ready to be saw-cut to size.

Vermiculite form

Saw-cut and pre-fired vermiculite boards will be assembled into a container to harness the flow of glass as it heats in the kiln.

Vermiculite form

I primed and kiln-dried the vermiculite boards to prevent glass from sticking during firing. That was my first fatal mistake. I should have lined the walls with fiber paper or used primed fiber board instead of vermiculite to prevent sticking.

Vermiculite form

Pilot holes are drilled.

Vermiculite form

Loosely assembled vermiculite form.

The vermiculite containment form turned out fine. The plaster/silica investment core turned out fine as well. After several tries I was able to stack the cut-glass strips snugly between the core and box walls. (I forgot to photograph this process.) From this point on, everything that could have gone wrong did go wrong due to bad judgement calls. The glass stuck to the vermiculite form, the glass cracked, and the mess you see below is the result. Do I understand enough at this point to try it again and is it worth it? I haven't decided yet.