Sat, Feb.12
7:00 am

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Earthen and Lime Plasters: I have been asked for my recipes for the earthen and lime plasters in my home, so here they are. These are very simple recipes and not "gourmet cooking". I am a simplist on a budget. If you are a perfectionist and willing to spend some money, you can research the internet for professional plasterers and for companies that specialize in refined products. My plasters are made from ingredients that cost about $8 for 50 lb bags, plus basic clay colors. You can grind up dried berries or use any other powder to color them, too. So, with that disclaimer, here is how I cover my walls (at the bottom, I talk about how to do this over regular framed walls, also):

EARTHEN PLASTER/COB: The first coat which shapes the walls and fills in the gaps and dents between bales is your basic cob or earthen plaster made with high-clay soil that I recommend purchasing from an adobe company, mixed with chopped straw and water. If you need large quantities and have a group of people ready to help, then rent a mortar mixer. Make some small batches first to get your formula down. Put some water in a wheelbarrow and then add a bucket of clay soil. Adjust the mixture until it is chocolate milk consistency. Stick your hand in and if your hand comes out coated, you have enough clay in there. If the mixture slips off your hand, your soil doesn't have enough clay and you'll have to get better soil. If it doesn't coat your hand, it won't coat the straw. When that is good, fill some big trash bags with chopped straw (I recommend finding a leaf mulcher to do the chopping). Add the straw until you have cookie dough and then you are ready to go! Spray clay water onto the bales to get them moistened and sticky - we filtered clay soil very finely and blew it on with a stucco hopper. You can also must make a very thin mixture of clay/water and apply with your hands. Keep it moist with a hose mister as you work. Then glop on the cob with trowels or by throwing mud balls at the walls and smoothing them. Wooden trowels will leave it rough enough for a second coat and metal trowels will smooth off the final coat. Use this thick clay plaster to shape areas around your doors, windows, or create art on the walls. You might not want too much straw in sculpting mixtures, because it makes rough edges, but you could either chop it very fine or use mortar sand to thicken it.

FINISH COAT: Then, when your walls are smooth enough to keep you happy, you may want a finish, color coat. You can use either clay or lime for the base. Clay is stickier, but less weather and water resistant than lime. Clay also can darken over time, but lime stays bright. However, lime is alkaline and you have to take precautions. Keep it off your skin and don't breathe the dry powder. I coat my hands with mayonnaise which has vinegar in it, use double-rubber gloves, cover my breathing passages when I'm mixing it up, and rinse my hands in vinegar at each break.

EXTERIOR LIME PLASTER: On the outside of my house, I have a coat of peach lime plaster, colored with ferrous sulfate fertilizer. Here is how I made these. You can double, triple the recipe as needed: Dissolve 1C ferrous sulfate fertilizer (available from wholesale landscape companies) in 4C water in a bucket. Add 4C powdered S lime (from home improvement stores) and 4C #60 silica sand (available from sand-blasting suppliers or some building suppliers). Mix it well to remove all lumps - a beater or large wire whisk work well. It should be stiff enough to stay on your trowel. It will be blue, but don't freak out - it will rust as it dries and turn peach. If you want to see what color it will end up, stick a wooden spoon in the mix and then dry it with a hair dryer. If you want it darker or lighter, adjust the amount of ferrous sulfate. Trowel a thin layer over your rough and damp earthen plasters. I roughed up my plasters with a wire brush first, but if you left yours rough, then you should be okay. Lime is slippery, but keep at it, always stroke upward and the technique will come. Dampen the base plaster with mist from a hose or a sprayer, as you work, so you aren't applying to a dry surface. Let it dry for one day at least and then go back with a very watery, thin coat made the same way, but add more water. Use a grout sponge to smooth over any ridges, cracks and trowel marks from your first coat. You can use the rough side of the sponge if you need a lot of smoothing and then the smooth side of the sponge if you just need to spread the color. Use lots of water and a circular motion to cover the whole area. Let it dry and presto - you have a lovely wall that will allow the bales to breathe, but protect them from the weather and looks like soft suede. You can use powdered clay to color the lime, if you don't want peach, also. I have had trouble with the ferrous sulfate color, if I try to use this without sand, making only a paint of lime, ferrous sulfate and water. I don't know why, but it does better as a plaster with sand.

INTERIOR CLAY PLASTER: On the inside of my house, I coated the earthen plasters with a fine coat of off-white clay and then I painted them with a lime paint. If your base earthen plasters are smooth enough, you could move right to the lime paint. Here is my recipe for a basic colored clay plaster: Get a large bag of powdered white clay from a pottery-supply store and then some smaller bags of whatever color clay you want. Basic white clay is a little gray - like unglazed pottery. I added a little yellow iron oxide to take out the gray. Mix up some tests until you get a color you like. Put a few cups of water in the bottom of a bucket, so the clay doesn't stick at the bottom, then add equal parts of white clay and #60 silica sand with the amount of colored clay that you want. I used 10C white, 10C sand and 1C yellow iron oxide to get my basic wall color. Add enough water to make it cookie dough consistency. Trowel on as I mentioned above and then do a sponge coat to smooth it also as mentioned above. You can experiment with ground mica instead of all sand, with using different coloring powders, and remember to imbed a few shells or colored glass and sculpt something fun! When you have a surface that you are happy with, make a mixture of about half/half white glue and water, and paint it over the surface to keep the sand from sifting down and give it a little water-proofing. I buy the glue by the gallon at Lowes.

LIME PAINT: I have found that clays darken over time, so I am now coating my walls with a lime paint. It is brighter and more durable, but more brittle than clay. Note the lime precautions that I mention above - it is very caustic when wet and you should not breathe in the powder. This one is easy: mix powdered S lime and water to paint consistency. Add colored clay to make it the color you want! Test the final color by coating a wooden spoon or paint stir stick and dry with a hair dryer. My basic wall lime paint that is slightly gold, is 4C water, 4C lime, 2Tbsp yellow oxide, 1/4 tsp red oxide (be careful with this red - it really stains!). Mix and apply with paint brush. When dry, coat with a half/half mixture of white glue and water.

FOR FRAMED WALLS: To do this on a framed, drywall wall, buy rolls of burlap from a home improvement store, garden department. Cut a strip of burlap to fit your wall, then mix some clay and water in a bucket, soak the burlap in this mixutre and then put it up like wallpaper. This is really messy, so cover everything in the area! I used push pins to hold the top in place, while I spread out the rest of the burlap. This will stick to the wall as it dries and give your wall a texture over which you can plaster - or you can leave it up there as burlap wallpaper! I had some ladies come on the home tour and tell me that clay plasters give off negative ions and good vibes. =) I don't know about the ions, but I do like the vibes.