Cob workshop writeup
Aug. 8th, 2006 07:39 pm![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
helen99We spent the weekend at Heathcote - an intentional community that ![[livejournal.com profile]](https://www.dreamwidth.org/img/external/lj-userinfo.gif)
rhiannasilel told us about a while ago. They were offering a cob workshop, and for a once, we weren't already booked and they didn't cancel.
The workshop was centered around the task of encasing a masonry stove in cob (a thermal mass) so it will collect heat and continue to radiate it long after the fuel is spent. We also built a cob bench and applied earthen plaster to walls bordering a couple of windows. The stove, bench, and windows were situated inside a strawbale house that the Heathcote community is currently building to house one of the families who lives on the land.
The cob that was used for the stove was not allowed by fire codes to contain straw, so I still haven't had the opportunity to play with actual cob, which is a combination of clay, sand, and straw. The cob used on the stove was sand and clay only, which means its tensile strength was greatly diminished. To compensate, a larger amount of sand was used.
The cob bench did have straw in it, but there were a limited number of spaces to work around the bench, so I didn't get to play with it. Rialian worked on the bench for a short time, though. He thought the bench cob contained too much water and not enough straw, which made it considerably weaker than it should have been. According to Ianto Evans (The Hand Sculpted House), cob is supposed to have enough tensile strength to resist being pulled apart if two people tug at a ball of it from opposite sides. The cob we used on the stove was easily broken, and the cob used on the bench was wet and barely held together. It had to be propped up with bricks while it dried.
This is why we suspect that everyone was learning during this workshop, including the presenter. Heathcote is just getting started with natural building, and they have a good deal of experience with what not to do, but haven't gotten it quite perfect yet, from the looks of what is already up. I have a feeling that cob building is a lot like cooking. You know when you have it right, but it takes a while to get the feel of what "right" is.
That said, it was a lot of fun to splash around in the mud all weekend!! There's just something about playing with mud that gives substance to one's form, for lack of a better way of putting it. I don't care if the whole thing was full of mistakes, that was the important part for me (and everyone was learning at the same time).
There were several tasks involved. The first task was sifting the clay and sand to remove debris and rocks. This was done by attaching some hardware cloth to a wood frame, which was then placed over a pair of 50-gallon trash cans. One person would shovel dirt onto the hardware cloth, and two of us would rub the clay on the hardware cloth which acted kind of like a grater. The clay then broke apart and sifted through the hardware cloth, leaving the rocks on top.
The large pile of clay which had been excavated to make the foundations of the house was the source of the clay. It was cool that they could use the materials directly from the excavation site to build the house. Builder's sand to mix with the clay had to be brought in from elsewhere, though. Once a large trashcan was full of sifted clay, the clay was put in 5-gallon buckets and placed aside, ready for mixing. Then the trashcan was refilled. After a bit of doing that, I decided to try something else.
I gravitated toward the task of mixing the cob ingredients on a large tarp. The proportions of clay, water, and sand were dictated by the presenter (that was the part that we found to be different from that described in The Hand Sculpted House and on http://www.cobcottage.com), but the mixing was done by participants. First, we dry-mixed together several 5-gallon buckets of sand and clay. The amount of sand used was usually larger than the amount of clay, but the proportions varied as we tried to get it to feel right. After it was thoroughly mixed, we sprayed it down with a hose, whereupon we ... jumped in it and began kneading it with our feet! The first jump is always the best, while it was still nice and aerated and wet and our feet sank all the way down. When it got too tough to sink into, then we would "roll" it (grab an end of the tarp and pull it until the pile flipped over). Then we'd spray it some more and jump in it again. After it got too tough/dry again, we'd roll it from an edge of the tarp 90 degrees from the first edge and spray it down again and knead it some more, and so on. The end result when the mixing was done was a huge, "burrito" shaped mudpie which could be shaped into loaves. The next step was to create hundreds of little loaves that could be applied to the surface of the masonry stove.
After that, I did some sculpting on the stove. I thought I was doing pretty well, until the end of the day when the presenter realized that a large crack had developed through the portion that I'd done. The reason was, I'd built up one side of a corner and then built up the other side of it, rather than keeping both sides even. The first side had dried a little bit and hadn't bonded together, so when it dried more, it pulled apart. A cob structure has to be built like a clay pot - building around the top evenly. Oops.
The last thing we did was to try to put some earthen plaster on the wall. The "plaster" was similar to the stove cob, only much wetter, and was applied with a hand trowel. I didn't do too well with this, because for every 5 inches I put on the wall, 4 of them would fall off! I think that if I ever make a plaster to use myself, I'll put something sticky in it...
I suspect my trowelling skills are not what they should be, because Rialian had no problem with it though, so he finished my window for me while I handed him mudpies.
So yes, we spent the entire weekend playing with mudpies, and it was good...
rhiannasilel told us about a while ago. They were offering a cob workshop, and for a once, we weren't already booked and they didn't cancel. The workshop was centered around the task of encasing a masonry stove in cob (a thermal mass) so it will collect heat and continue to radiate it long after the fuel is spent. We also built a cob bench and applied earthen plaster to walls bordering a couple of windows. The stove, bench, and windows were situated inside a strawbale house that the Heathcote community is currently building to house one of the families who lives on the land.
The cob that was used for the stove was not allowed by fire codes to contain straw, so I still haven't had the opportunity to play with actual cob, which is a combination of clay, sand, and straw. The cob used on the stove was sand and clay only, which means its tensile strength was greatly diminished. To compensate, a larger amount of sand was used.
The cob bench did have straw in it, but there were a limited number of spaces to work around the bench, so I didn't get to play with it. Rialian worked on the bench for a short time, though. He thought the bench cob contained too much water and not enough straw, which made it considerably weaker than it should have been. According to Ianto Evans (The Hand Sculpted House), cob is supposed to have enough tensile strength to resist being pulled apart if two people tug at a ball of it from opposite sides. The cob we used on the stove was easily broken, and the cob used on the bench was wet and barely held together. It had to be propped up with bricks while it dried.
This is why we suspect that everyone was learning during this workshop, including the presenter. Heathcote is just getting started with natural building, and they have a good deal of experience with what not to do, but haven't gotten it quite perfect yet, from the looks of what is already up. I have a feeling that cob building is a lot like cooking. You know when you have it right, but it takes a while to get the feel of what "right" is.
That said, it was a lot of fun to splash around in the mud all weekend!! There's just something about playing with mud that gives substance to one's form, for lack of a better way of putting it. I don't care if the whole thing was full of mistakes, that was the important part for me (and everyone was learning at the same time).
There were several tasks involved. The first task was sifting the clay and sand to remove debris and rocks. This was done by attaching some hardware cloth to a wood frame, which was then placed over a pair of 50-gallon trash cans. One person would shovel dirt onto the hardware cloth, and two of us would rub the clay on the hardware cloth which acted kind of like a grater. The clay then broke apart and sifted through the hardware cloth, leaving the rocks on top.
The large pile of clay which had been excavated to make the foundations of the house was the source of the clay. It was cool that they could use the materials directly from the excavation site to build the house. Builder's sand to mix with the clay had to be brought in from elsewhere, though. Once a large trashcan was full of sifted clay, the clay was put in 5-gallon buckets and placed aside, ready for mixing. Then the trashcan was refilled. After a bit of doing that, I decided to try something else.
I gravitated toward the task of mixing the cob ingredients on a large tarp. The proportions of clay, water, and sand were dictated by the presenter (that was the part that we found to be different from that described in The Hand Sculpted House and on http://www.cobcottage.com), but the mixing was done by participants. First, we dry-mixed together several 5-gallon buckets of sand and clay. The amount of sand used was usually larger than the amount of clay, but the proportions varied as we tried to get it to feel right. After it was thoroughly mixed, we sprayed it down with a hose, whereupon we ... jumped in it and began kneading it with our feet! The first jump is always the best, while it was still nice and aerated and wet and our feet sank all the way down. When it got too tough to sink into, then we would "roll" it (grab an end of the tarp and pull it until the pile flipped over). Then we'd spray it some more and jump in it again. After it got too tough/dry again, we'd roll it from an edge of the tarp 90 degrees from the first edge and spray it down again and knead it some more, and so on. The end result when the mixing was done was a huge, "burrito" shaped mudpie which could be shaped into loaves. The next step was to create hundreds of little loaves that could be applied to the surface of the masonry stove.
After that, I did some sculpting on the stove. I thought I was doing pretty well, until the end of the day when the presenter realized that a large crack had developed through the portion that I'd done. The reason was, I'd built up one side of a corner and then built up the other side of it, rather than keeping both sides even. The first side had dried a little bit and hadn't bonded together, so when it dried more, it pulled apart. A cob structure has to be built like a clay pot - building around the top evenly. Oops.
The last thing we did was to try to put some earthen plaster on the wall. The "plaster" was similar to the stove cob, only much wetter, and was applied with a hand trowel. I didn't do too well with this, because for every 5 inches I put on the wall, 4 of them would fall off! I think that if I ever make a plaster to use myself, I'll put something sticky in it...
I suspect my trowelling skills are not what they should be, because Rialian had no problem with it though, so he finished my window for me while I handed him mudpies.
So yes, we spent the entire weekend playing with mudpies, and it was good...
![[identity profile]](https://www.dreamwidth.org/img/silk/identity/openid.png){kind=small}
(no subject)
Date: 2006-08-09 01:23 am (UTC)I can also tell that you have no feline in you at all. I'd love to play in mud, if it weren't for it getting in my claws, my fur, and my hind paws.
(no subject)
Date: 2006-08-09 01:47 am (UTC)(no subject)
Date: 2006-08-09 02:04 am (UTC)And you are so right--in fact, the best mask I ever found is the one by Burt's Bees. All that's in it are French clay and herbs. It's wonderful!
(no subject)
Date: 2006-08-09 11:37 pm (UTC)Apparently it didn't always look like that, though - they'd cleaned it up and set it up all nice for the workshop.