Well after noticing the beginning of some deterioration on one of my SAW kit moulds, I'm now using release spray after every cast. So I wanted to instigate a bit of a discussion about release agents.
The primary purpose of the release agent is to prevent the resin from sticking to the silicone mould. At first this may seem silly, as the only thing that seems to bond to silicone is more silicone! But just because the silicone and resin don't bond, they still do stick together slightly and in the process of demoulding a bit of extra stress is placed on the mould. By giving the mould a release coating, the resin sticks to the silicone much less readily and the difference is very noticeable when removing the part from the mould.
The secondary purpose of the release agent is to help prevent bubbles (the ones that aren't going to be compressed small enough from the pressure) from sticking to the silicone and thus rise up and out the vent(s).
On an uneducated whim a while ago I bought some Mann Ease Release 200 spray. I don't use anywhere near as much as the instructions on the can specify. I just give the mould a light misting now each time after I demould. I'm not sure now well it works for preventing bubbles sticking, but for that I use a second agent in conjunction with the Ease Release 200: talcum powder.
I picked up a big bottle of baby powder for only a couple of bucks. It smells nice
When preparing a mould for a cast, I pour it into the mould and then use a big soft brush to dust it all around. Then I hold the mould upside down over a bin and tap the excess (most of the talc) out.
So has anybody else had any experience with other release agents?
How much do you use?
Is there much difference between the different brands?
Do you use the same release for both resin to silicone and silicone to silicone?
Do you notice a significant improvement in mould longevity when using the release?
On a related note, the release agent I use for silicone to silicone (in two part moulds, etc.) is good old Vaseline. It's cheap, easy to get a hold of and works fantastically. I bought it in this little metal tin (it's an aloe vera one that's intended for dry lips) and to use, I simply spatula a bit into the lid and use a lighter under the lid to melt it down nice and runny. Then I just brush it on. Easy!