2004-12-17

Tried casting with:

• Epoxy
• Polyurethane
• • stuff for Shore A 95
• • mixed it 2:1 instead of 1.5:1 to try to get shore A 40

I did some small pieces with embedded LEDs in the silicone RTV molds from before. The LEDs are pretty satisfying – you can just see the dome. Really what you see are the wires and metal. The small pieces were mixed and cured outside. Temperature went down to 10C.

Also did some X-mas ornaments at the bottom of paper cups. These were cured inside (approx 16C).

The ones cured inside definitely came out better. No real surface tackiness on the epoxy, but it is kind of squish at the edges. The polyurethane is slightly tacky.

The epoxy done outside is tacky and squishy at the edges. The poly is way goopy and not very good. These are currently in the toaster oven on low. This seems to make them more flexible while the temp is up.

Starting to think that a toaster oven setup with an exhaust fan might be an interesting idea. Could be used without the fan for toasting SMT boards.

To do:

• get a scale and actually mix things with accuracy
• figure out way to control temp
• find something to use other than soft modelling clay – it tends to smear over stuff and be hard to remove
• investigate thermoplastic – potentially less toxic than polyurethane/polyester
• get some mineral oil – use to dilute petrolatum jelly to reduce size of streaks