Attempt 1
This time I bought some new porcelain tiles from a local store for $5. Apparently glaze on tiles are slightly softer than porcelain, but per advice I just placed the tiles upside down. Mirror sat below, then plastic wrap on top, then tiles, and finally dental stone gets mixed and poured on top. Dental stone is a waterproof plaster that hardens fast; last time it hardened in my bucket after just 15 mins of mixing. This time I set a timer for 8 minutes to pour, and used a thinner ratio if around 45 mL water to 100 g powder. I accidentally lifted up some tiles with a sticky hand, but it poured successfully! Now I can use this tool for the first half of grinding that 12" meniscus blank I made into a mooth mirror!
