Fluid propertied of RTV silicone

[Vidaman]

Is anyone aware of any peculiar properties of uncured RTV silicone that would make it particularly difficult to seal against? I have a spool valve that works great with every fluid except RTV silicone. With RTV, the double lip seal that seals between the reciprocating shaft and the atmosphere cannot contain the RTV for the same cycle life as it can for other fluids. Obviously there is the fact that the material cures, which may be the root cause (I'm only just starting my investigation). But are there any other properties to consider when sealing against uncured RTV.

Thanks,

Mike