Thursday, June 19, 2008
I melted some clear plastic spoons down in the oven. It's in a leftover artichoke jar. I'm not sure what kind of plastic they are, they're not really marked, if you squint it has B-4 on the handles, but it's not HDPE, it's probably some kind of PS, it was stable boiling in water, was a bit sticky at 350 F (176 C), but that might have been uneven heating from the broiler. It started gloppy flowing a bit at 400 F (210 C), so I bumped it up to 450 F (232 C), which made it pool in the bottom, but as the oven got to temperature it started smoking, so I shut it off and left it in the oven to cool slowly, so that the glass wouldn't break. Oh yeah, don't try this if you aren't ready for the jar to break, I expected it to break, I had it in a cast iron pan and it was preheated to even out the temperatures. The result is about 2 cm of hard clear plastic from having the jar full of broken pieces. As the jar cooled the plastic pulled away from the glass, making sounds that were very similar to cracking glass. There is a bit of bubbles in the plastic, but I think that this might be a workable way to cast plastic parts if you had an open faced mold, it was much to sticky to pour through a gate without something like an extruder.