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Earthen Plaster

PostPosted: Sun Sep 07, 2014 10:49 pm
by mannytheseacow
Coming up on the plastering this bench soon and I really want to go the earthen plaster route. Anyone have any tips, advice, etc? I did a basic plaster on my first bench using flour paste, sand, and clay soil. I've been messing around on my little 4" cookstove with just sand and clay soil. My new bench I want to try the manure plaster.

So I went into the pasture over the weekend and picked up a pail full of manure. Some nice green fresh warm slimy piles and some dried up chips too. I put it all in a bucket and added some water. Put the lid on and have it sitting in the sun. I'm going to leave it there for a while. Some of the manure had maggots in it so I'm hoping it kind of cooks itself. Definitely looking for some insight from others who have done this, as well as documenting it here in the forum for other folks to learn from.

Re: Earthen Plaster

PostPosted: Sun Sep 07, 2014 11:16 pm
by pa_friendly_guy
I have never tried to make any plaster of any kind. From what I have heard and what I have read horse poop seems to be preferred because it contains more fiber. Since the horses do not chew the cud there is much more stuff in it that passes through the horse that is chewed up by cows, sheep goats etc. That fiber helps the plaster hold together. The fellow that built the straw bale building that I saw in class made his plaster from hydrated lime and water. He used it both inside and outside of the building. He made it into a thick heavy paste and just slapped it on. The outside plaster he had added a natural dye [ iron oxide ] that turned the plaster red. It hardened to a very hard, very durable plaster. He claimed that the lime turned back into lime stone as it dried and hardened.

Re: Earthen Plaster

PostPosted: Mon Sep 08, 2014 2:29 am
by matt walker
I use cow poop, since it's what I have. I have never done the fermentation gig though, I never plan that far ahead. Lately I've been using the fire clay as the base since that eliminates the screening of my local stuff. I can get a really smooth plaster that way. I put a couple inches of dry fire clay in the bottom of a five gallon bucket, then use a paint mixer on a drill motor to stir as I add water/flour paste/manure liquid from another bucket. I go for milkshake consistency, then start adding in sand until it gets too stiff for the mixer. At that point, it's pretty much there. Might need to massage it a bit by hand, but that usually gets you close without too much effort.

Re: Earthen Plaster

PostPosted: Tue Sep 16, 2014 7:49 pm
by mannytheseacow
I tried my first manure plaster application this past friday. It really stunk but I expected that. The mix I ended up with was 3 parts sand, 2 parts water, 1 part manure paste, 1 part clay soil, and 4 parts flour paste. I didn't really notice any difference from the non-poo plasters that I've made aside from the smell and the putrid green hue.

It dried within a day. I've been burning pretty hard, fans on, windows open, dehumidifier on, air exchanger on, etc. I'm pretty sure the mass it dry and the plaster was dry within 24 hours.

The whole house stunk for the first 24 hours. Now there is just a faint smell of cow manure in the room with the bench. Sticking your nose near the plaster, it still smells awful! I think the rest of my plasters will be non-poo. I guess I'm just not that "natural".

I also have to mention what a trooper my wife has been through this. I think anybody else would have given me the boot when they came home to a house stinking to high heaven with cow manure. She just holds her nose and kind of laughs about it. She was definitely relieved when I told her I was leaving it out of the next batch.