I've been wanting try this for a long time. I'll play with it on the Mask HD and let you know.
Here are my thoughts after having worked with this stuff on the medical side of things:
Silicone is generally accepted as biocompatible, meaning it shouldn't harm living tissue. Just about every disposable medical device has silicone on it or in it (needles, IVs, valves, etc). Having said that, it's generally frowned upon to allow it to mist and enter into the lungs. I had to set up one manufacturing process where we sprayed into a protective cover that went over a scalpel. It was a prototype machine that required manual operation from several feet away. Even though we were only spraying micrograms of silicone, it would still coat the operators safety glasses. We joked he was going to quickly develop "slick lung" and gave him a face mask and shut it down as soon as possible we could fully automate it.
10,000 to 12,500 cST is a thicker viscosity. I don't know why, I always liked working with the thicker stuff better. It gets EVERYWHERE way too easily.
When you get a shot or an IV inserted, the reason why it goes in so easily is because A) the needle is freakin sharp, and B) it has a coating of silicone oil on it. The needles will have it baked on. For a thinner layer, the silicone is cut with scary chemicals like hexane and surfactant-like additives, dipped, and then baked.
My recommendation is if you do this, don't leave much left in the can because the blow back will not exactly be healthy for you. I'm not going to say it's toxic either, but the less you get in your lungs the better. I would be especially wary of getting a lung full of vaporized DOT 5 with all of its crazy additives. Again, not saying don't use it, just don't leave the stuff puddled in there like you would in wet a suppressor if you're going to do it. I feel better about handling "the Dip" than imagining breathing in a mist of silicone.
Oh, and it's 100% fine for aluminum if anyone is still wondering.