[GSBN] Exterior plaster sealer?

[Tom Hahn]

Ultimately, I'll defer to John's expertise with them, but we have 
also had good experience with siloxanes... admittedly not under such 
severe conditions as you describe, Darrel.

Depending on the surface type/texture, there are several variants in 
the water-based EnviroSeal line that we have used on even very 
open-pore surfaces, with good results (and little or no visual sheen 
or color change).

Tom Hahn
Ecosa Institute/Ecosa Design Studio
Prescott, AZ