I think both blue and green boards mold resistant clams are based on the chemical treatment of the paper binding the material rather than the gypsum itself. Since I think the manufacturing process is an industry secret I haven’t been able to find out.

Some times in a situation where plaster appears to be molding on the surface, its really the residue paste of removed wallpaper that the spores are feasting upon.

I never thought I would have so much fun discussing Sheetrock.

As for your point about holding up better in moderate water leaks, I’m afraid my only experience with rock-lath is on the Coast after Katrina, so combined perhaps we have a full experience with the stuff. The house I saw that had the rock lath had taken about 4 feet of water in the storm surge (not sitting flood water, but a surge that went in and then out again a few hours later). You could tell exactly how high the water had been because below was completely black and above was just fine. Meanwhile the plaster walls on regular wood lath had no mold at all, unless they had been locked up tight with wet furniture and such.

From my experience, moderate water leaks are harder on plaster (which turns into a pile of chalk and sand) than drywall (which can actually get sopping wet then regain most of its original strength when it dries, especially if the water can drain through the nail holes). Rock-lathe plaster is somewhere in between; it either survives with almost no damage, or it falls apart. Chronic low-level moisture is probably where real plaster has an edge, since the wood lathe is much less susceptible to mold. I’m not very familiar with the effects of flooding and I hope it stays that way. Maybe the “mold proof drywall” they have pushed on and off will prove to live up to its promise; it would be a bit closer to the best of all worlds.

Thanks for the cool article!