Hi,
I am wondering if I apply aged lime putty mortar over already existing "gypsum plaster" (it is placed on metal lath). Is it going to be some dangerous effect for my fresco painting. Usually how long need efflorescence to shows on surface. Or is it going to be problem for lime mortar to setting over it. I would like to know some more about that, is that permanent enough or is possible after longer time salt from base coat to destroy surface.
Thanks for help!
Filip