This image of plaster prep on straw bale walls in the straw bale hybrid home highlights a mix Carolyn developed to combine the clay slip and infill coat, saving one entire pass on the walls. After many years of applying heavy cob infill coats which take much time and effort to fill in the small uneven areas of a straw bale wall and serve to level them up, Carolyn began thinking about options. Also after hand applying clay slip, which will drip down sleeves endlessly and slap into the eyes, or using a stucco sprayer, which can clog if any particles which are too large get into the sprayer, it was time to experiment.
After reading about different plaster techniques used in areas where materials may not be the best, or even available, there was a small blurb about heavy straw, heavy clay which caught Carolyn’s attention.
She decided to play around with a mix of medium to finely chopped straw mixed in a heavy clay slip and see if it would serve to both key in the mud into the raw straw bales, and also to serve as the infill coat to level up the walls. After a series of experiments with formulas, she arrived at a perfect mix. It is light weight (cobbers will appreciate this aspect), easy to apply, not too drippy and the best of all – can be applied between 2-4 inches and then some.
Carolyn now will use nothing other than this mix to prepare the walls for the first earthen coat of plaster. It was used for all of the walls in this straw bale hybrid home with nary a crack appearing. She is sold on the idea and will never go back to mixing heavy cob by the hundreds of pounds (even though she loves cob!).