Sunday, October 4, 2009

The Evil Chicken and his friend, the Footed Toothfish

It's been quite a while since I've had an operable camera on the cottage site, but those days are over(!). The building has gone through a number of visual changes in the past couple of weeks. My latest undertaking was purely for aesthetic value - both to cover up cracks in the red earthen plaster, and to add general character to the otherwise plain north and west walls.



You may be thinking: "but, but, but it looked pure, and simple, and beautiful before the mural. Now it's a bit too much; visually overwhelming, even. It takes attention away from the gorgeous foundation stones, and adulterates the curve of the roof."

I've thought the same things. However, it was an experiment, and a fun one at that. I don't think I'd ever do it on my own house.

But as far as positives go: it makes the house very unique - I specifically avoided certain subjects in my mural that I find corny and overused: hands, the sun, moon, stars, happy faces, flowers. It looks especially good from far away, like in the garden, which is where most people first see the cottage. I hope that it draws crowds down through the garden fence to get a closer look. Most importantly, the lime plaster covers up all the unsightly cracks that opened up in the earthen plaster beneath it. In fact, the shapes in the mural (including the Footed Toothfish and Evil Chicken) are based on where the biggest cracks were that I wanted to hide. The art created itself as I went along.

The earthen plaster had to be scratched and partially saturated with water to provide a good bonding surface for the lime plaster.

Here is the gardener's view (the origin of the mural is where the stove pipe exits through the wall - it's supposed to be like flames and monsters are shooting out from the pipe and around the wall, kind of) :

The drying process for the lime plaster was really neat. The plaster is actually mostly sand (1 part lime putty, 3 parts sand, 1/2 part horse manure). As you can see below, the freshly applied plaster is more the color of the sand, but the white lime completely takes over the color as it dries.

I don't know much in detail about the process that lime goes to - Mike is always able to explain it more fully (he was a chemistry major). Basically, limestone is mined, crushed up, and then heated in an extremely hot kiln. During this heating process, CO2 is released. (Then a lot more happens....) When you buy lime in the United States, it is sold in dry, powder form. The powdered lime is "slaked," which means that it is mixed with water to form a putty. The putty is stored under a layer of water to prevent it from being exposed to air (which will cause it to harden). The longer the putty is stored, the better it gets (can't remember why) - the putty I used has been sitting in a 55-gallon drum for 4 years! The putty is mixed with sand to make a plaster. When the plaster is applied, the lime pulls CO2 back out of the air, and goes through a chemical change, turning it back into "stone." So a coat of lime plaster on a wall is essentially a coat of really thin (and breathable) stone. It is more durable than an earthen plaster, which is why we used it on the exterior window sills (no photos, sorry) where rain water might sit for longer than on a vertical wall.

Up close, the lime and earthen plaster look very similar in terms of texture. This is because they are both mostly sand. One has clay, one has lime. Both have a little bit of horse poop, which provides tensile strength (if you ever pulled apart horse manure, note how it's mostly all grass, broken down into short bits). When I first started to touch and break up horse poo, I was a bit disgusted. Once I started thinking of it more as "grass that has been processed through a most beautiful machine using natural enzymes," it wasn't bad at all. In a plaster, the grass acts to hold things together and prevent cracking once the clay starts to shrink. It's like the rebar in concrete, but on a tinier scale.

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