Searching the archives, I found a few references to sealing colored plaster, but none that specifically answered my question.  I am going to skim coat blue board with Diamond finish with LaHabra stucco color added to the mix.  I want to seal the finished plaster.  USG makes a sealer- has anyone used it?  I want so use something I can paint in the future, in necessary.  That means I can’t really use a polyurethane based sealer, or a silicone based sealer.  Does sealer darken the finish much?

USG reccomends taping with Durabond (or setting mud), then finishing with Diamond finish plaster.  Does anyone just use Diamond finish on the joints, then another skim coat? 

Thanks