Hill's Space

Meniscus mirror: draping success!

 |  1 min  |  145 words
A 12" diameter circle of glass!
The draped glass blank viewed from the side. The kiln has curved it so its sides are 1/4" above the table its center rests on.
The same glass, viewed to catch the light and highlight dents in the glass or bubbles. Two big pits are circled. There are many ripples and a few very small pits, but nothing big!
The furnace cement tool that helped curve the glass. It almost seems to have bent itself upside-down; the top part (which used to be curved) is flat and the bottom part (which used to be flat) is curved.

I got the news from my local glass studio in an all-caps email that said nothing but “IT WORKED!”

Look at this! My glass is now clearly curved, around 1/4" taller at the sides than at the center! That’s very close to f/4, my goal! SLUMPING DRAPING: SUCCESS

Weirdly, even though the mirror is the right shape, the cement form seems to have warped. The top face is now flat, and the bottom is now curved - which is weird because originally the bottom was flat and the top was curved. The bottom side looks… cracked? Like the bottom expanded? Maybe the water I sprinkled on top to prolong crystal formation ended up causing something weird.

The mirror is pretty smooth except for two pits, each 1/4mm deep. I circled them in black. Not bad at all!

Next steps: grind it smooth to within nanometers!

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