The silicones that have been tested successfully are Tin-cure RTV silicones, such as Silpak R1348, or Smooth-on Tin-Cure Silicone Rubber. You can cure the silicone around the print without the need of a coating.
On the other hand, Platinum-cure resins are much more sensitive to trace amounts of catalyst inhibitors. We have had several reports that these silicones will not cure completely on the surface of untreated, fresh prints. We recommend post-curing the prints thoroughly with a low wavelength (365nm or less) UV oven and using a Polyviny Alcohol (PVA) release agent to cover every surface of the print that will come in contact with the Platinum catalyzed RTV rubber. Similar protective barriers are also available as acrylic varnishes. The PVA barriers can be dissolved with water but the acrylic ones are permanent.