Is there a way to quantify phrases like "a little wet"? I have read many posts about constructing with cob, earth bags, rammed earth, etc that use phrases like "add water until the soil is a little moist". As a newb, I feel a little uncomfortable with this. If it were my occupation, by the time I was halfway through the 2nd or 3rd building I would have an intuitive sense of what "a little" means, but the nature of my needs - as well as the needs of many people in this forum - most people will not be building one house after another, and will not have the chance to develop that intuitive sense. I don't want my learning curve to result in half of the walls of my house falling down after 3 years. I have seen moisture sensors used to test the amount of water in the soil of house plants. Can something like this be used?
I can hear your frustration, and this is a common and understandable one. Each clay type is a bit different so I am not sure if even a moisture meter would give the exact number we could use. I can share "ranges" for folks...
A "little wet" in my experience with cobb and related, is a "washcloth well wrung out." It is damp and a little wet but not dripping. Each clay types does have to be experimented with. I look forward to others views on sharing this "little wet" topic...if there is a better way to share with students I would love to learn it...
This is absolutely one of those things that can only be learned by doing. My cob experience to date involves building two cob ovens and one RMH, so no load bearing walls or other critical structures, but I can say that even that small amount of experience is enough to start getting a good handle on what works.
Erica Wisner has a post in the PEX/PEP1 forum on the Cob thread there that addresses some of this. Her husband Ernie trained at Cob Cottage Co., one of the foremost cob education groups in the country. In her post she cites his observation that there is a constant process of adjusting the mix when making cob, as the materials are just not uniform.
Considering the large amounts of cob involved in doing even a modest sized structure, there is lots of opportunity to figure out the "right" feel and how to get the mix to that point.
It is more frustrating when reading about it than when actually doing it
As it was said you don't need to worry about it. To little and you won't be able to mix the ingredient, to much and it will start flowing and there's is a margin in between. If you stay closer to to-ittle than to to-much it'll dry faster.
posted 5 years ago
I guess I am just too "wet behind the ears"
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