By "seal" the mold do you mean use a release agent so that the master comes out of the mold or are you talking about some kind of preservative coating on the silicone?

Also, I gather you didn't use the thinning agent?

As it may help to explain my initial goal with this mold, I want to make one of these...

p068.ezboard.com/fhirstar...2351.topic

Thanks again,
GW-