I tried the resin again, this time using the vacuum chamber.
I mixed it up (using a different glow in the dark colour this time), and cycled it in the vacuum chamber a couple of times. The resin mixture also did the boiling in a vacuum thing! Yay!
Once I removed it, the liquid looked really clear: all the bubbles had gone.
Recap of Problems
So, lets run through our problems from last time
- A: (big bubble): gone.
- B: (crap in mould): gone.
- C: (bubbles): gone.
- D: (concave base): much better now, but still slightly present. Easy fix when making a mould next time though.
There is a new issue though, the epoxy doesn’t seem quite solid as solid as before: its ever so slightly bendy compared to attempt #1.
I think I didn’t spend long enough mixing it this time, which I was careful to do with #1. I was too excited to try it out in the vacuum chamber.
Reading a bit more on Silicone moulding shows there are two types of silicone, both with two names for extra confusion:
- Tin Cure/Condensation Cure – This is what I’ve been using ‘cos its cheapest!
- Platinum Cure/Addition Cure – This is better for numerous reasons, but is more expensive.
Platinum cure is better for epoxy resin as the Tin cure can apparently interfere with the Epoxy curing process. It can also cope with much higher temperatures, and can in some grades be skin and food safe.
In this case, however, I don’t think the Tin Cure Silicone caused my epoxy setting problem since the original (Blue) owl set fine using the same mould. I’ll see if the new one sets in a few days.
I’d like to try a completely clear, smooth epoxy cast next to see what the surface is like. I’m enjoying making the opaque glow in the dark items, but I also want to create some objects to show off embedded delicate things. I guess I’ll also need to read up on polishing epoxy resin items as well.
Ooh, as I said, platinum cure Silicone can also resist much higher temperatures: I fancy some Pewter casting sometime soon!