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mold on natural plaster

 
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Hey y'all
I'm in humid Georgia and just put up a natural plaster recipe onto drywall.  It's a recipe that I used to use in California without a problem.  Unfortunately it's been really wet and rainy here and 90% of the walls now have a fuzzy mold on them, which is no bueno at all.  I was thinking of either bleaching them or painting them with lime water and then potentially re-plastering them with the same mix that has borax added to it.  I haven't done much natural building in almost 15 years though and I'm very limited on time (running an organic farm during peak season while doing this), so I can't really go through much more trial and error than I already have and I'm currently way behind on finishing this necessary building.  Any experienced recommendations would be greatly appreciated.
Thanks in advance,
Steve
 
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Location: Victor, Montana; Zone 5b
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Hello, I had the same thing happen to my place when I plastered too late in the year and the humidity was high in the house. I found making a solution of borax and clove oil cleared up the walls pretty quickly. The mold will die once it dries and then you can easily paint over with a clay alis or another finish coat of plaster with an anti mold agent like you suggested. Good Luck
 
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hey steve ...
that s not nice. may i ask what recipe you used for your plaster? and welcome to the forums.

would a lime plaster stick to your plaster? i think, this would be the best option for humid climate.

good luck
 
Steve Rovolis
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Thanks guys.
Honestly, I'd like to avoid a lime plaster if possible.

I just sprayed the walls with a bleach solution and the mold immediately disappeared in most places, except where there was some dark growth.

Next, I intend to re-plaster the remaining walls and ceilings with a commercially produced wallpaper adhesive instead of flour paste, due to the fact that it has a mildew-cide in it. I also intend to add borax to the mix.

I'm not sure in what ratio though as it's been a long time since I've used it in plaster (suggestions welcome). I then intend to paint all the walls with a lime-wash in hopes that it alters the surface pH to be less hospitable to mold and mildew.

The existing recipe is 2 parts fine play sand, 1/3 part 200 mesh silica, 1 part kaolin clay, 1/4 part flour paste, 1/16th part titanium white, and a pinch of control fibers.
thanks again
 
Daniel Ray
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it is always good to remember that lime plaster sticks to lime plaster, and earth plaster sticks to earth plasters, but they don't mix well in layers. They breath differently and will eventually crack apart given time.
 
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Could you get the mixture to work without flour/adhesive? Maybe in thinner layers or more/less water. Fungi are definitely harder to kill than humans, so I prefer not to feed them instead (no organic components).
Does the dry wall itself contain organic components?
 
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Hi . I live in humid northern New Zealand. Borax works as a fungicide. Bleach is temporary and doesn't kill the spores. We use Titree oil here in water 10/1 oil. The idea is the oil smothers the spores. Someone suggested clove oil. I'm thinking any fine organic oil would work.
Please dont put lime onto earth.. asking for trouble as have different vapour retention rates ..unless you really know what you are doing ... good luck.
 
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Kia ora Esther, and welcome to permies! Good tip there.
 
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If it's white hair mold then it's harmless, put a fan in the room of a dehumidifier.  It will eventually die and can be brushed off.
 
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I have been told that bleach has too much water content to do an effective job of killing mold. It was suggested to use hydrogen peroxide instead.

I like the suggestion to use lime based, because I have heard that it is too alkaline for mold to even grow.
 
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