When living in a Tiny House the issue of weight is something that has to always be taken into account. Often this excludes the use of cob in any substantial way. There are few things like the touch and warmth of cob. Most of the walls however are sheetrock and normally that limits when you can do with it. Cob does not stick to sheetrock but peels and crumbles off.
I had worked with a flour paste cob slurry before and knew there were ways around using normal cob but I wanted to find an easier and less labor intensive means to do it. The flour you have to cook down and into a paste and get the texture and mix right or it would be too runny or too think and not work well. Not everyone has the time to perfect the method so I wanted to find an easier way. What worked was taking sheetrock mud, you can get a large box from any home center, and mixed it with a clay soup.
When the two were completely mixed, to the consistency of thick soup I used a large brush and simply painted it on the walls. It took barely two coats but went on quickly and easily with the sheetrock /clay mix sticking to the wall with no issue.
Like with all cob work as it dried it cracked a little but with a damp cloth my fingers i simply smoothed it out, adding a small amount of clay to any areas that seemed to need it. I was able to get a smooth finish and the white of the mud-paster did not take away from the color of the clay itself.
As the work was done int he kitchen it needed to be sealed not only from water but from touch. Unsealed cob in time, will peal and crack from weather or wear. I chose to use boiled linseed oil. Normally this is mixed with mineral spirits in a 50/50 mix after the first coat but due to the chemical sensitivity I opted to just use the oil on its own.
I will warn any one who uses linseed oil, mixed or straight, it stinks. Fortunately the weather was above freezing and I was able to keep the windows open but the smell lingered for days after it had dried and that does not happen over night. I suggest doing this when you can leave all the windows and doors open for days.
The slurry did not bind well to the wood of the window frames. i had not expected it to but wanted to test it out. The windows will be trimmed out anyway so there was no worries with the effort. The work itself took me a full weekend with time to allow the cob and the linseed to dry between layers. It was a small space though and the time it took to get the smell out was closer to two weeks, but the end result I am very happy with.
The warmth of the color of the clay, as well as the feel of it, is a welcome addition to the house. I will be doing another two walls but not until summer is in full swing and the windows can be left open even at night.