I want to use mostly clay in my first coat, then a mix of clay, sand/silt, wheat paste in second and final coat I may use linseed oil. The truth is, I’m clueless! I put a test spot of clay on straw today and it won’t dry. I have no idea what that means. More clay, less water? I have been reading so many contradictory things that now I’m confused. I thought this would be simple but I need a little guidance.
Depending on the weather and climate and the substrate, a base coat of clay plaster 1" or so thick should stiffen up within a couple of hours, enough to not be workable, and firm enough to add more. It would probably not have dried enough to finish shrinking, meaning that both layers would still want to shrink, and you might get deeper cracks. In cool damp conditions, it may take longer.
I am not sure where you are living, but I am building a strawbale home in southern Arizona. It I very dry here, so Adobe dries fairly fast. I put an Adobe mix on the inside of our little cottage. The 1st coat which was straw, native soil and water mixed in a mortar mixer. This 1st coat took about 24-48 to dry, a couple spot that were a bit thinker took a bit longer to dry.
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