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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.
HAVE
FUN - THE MORE YOU DO THIS, THE EASIER IT GETS!
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