Silicone oily residue on cast piece

[fern7]

Hello

Looking for some advice -

I have been using Platsil Gel-25 to make a mold and then casting pieces with more Gel-25 in that mold with no issues - using a liquid wax release (mixture of white spirit and hydrocarbon wax).

In my latest cast piece I was working on cleaning up some seam lines etc and used an elastic band to hold back a side of the piece to keep it out the way of where I was working for an hour or so, and when I took the band off again I noticed a small amount of an oily residue where the silicone had creased up against itself.

Has anyone experienced this before / know what it is? I had previously cleaned the piece in hot soapy water to remove any wax residue from the release so don't think its that, and the piece feels well cured otherwise so I'm curious to know.. It was easy to clean off with some paper towel but I guess I want to know if this is anything to be concerned about ( if it might happen again or affect the longevity of the piece) as it is a piece I am selling,

Thanks in advance

 

[ChickenHaunt]

Sounds like the silicone is leaching. It happens sometimes. Some silicones are more prone to it than others. Age of the material will also play a factor. It will likely make it harder for paint to stick, because there's constantly a little bit of oil working its way out, and if you put it on an absorbant surface, it'll get oil stained, but that's about the worst of it, in my experience (which is limited, mind you).

 

[fern7]

Thanks for your response - I thought it might be this but was confused because I haven't done any of the things that might cause leaching (I didn't use any silicone fluid / thinners etc), I just had a small amount of pigment and flocking mixed in (the piece is of a human hand so going for flesh look)
At the moment it is only happening in the small part that I am folding back, but I dont know if it will continue to do it, or start in other places.

I wont be painting it, so I just want to know if what is leaching out is hazardous or harmful at all? As I am giving it to someone else I want to ensure it is safe to handle etc. Any advice very welcomed!

 

[mvaefx]

The less viscosity of the silicone = more silicone oil too leach. I discovered this using Smooth-On's Eco-Flex series platinum silicone which has a low viscosity. I alleviated the leaching oil by mixing a 50/50 mix with a higher viscosity silicone, like dragon skin. It cured the oily issue and sped up the curing time.