How to clay plaster - basecoat

[@kasgraham6348]

Please do post a video of the top coat. This was fantastically informative and helpful, thank you!

[@rossmcleod7983]

Triffic rundown Will, looking forward to giving it a whirl. Love your work.

[@RegretWhisperer]

great video, you explained your process well. i’m waiting for warmer weather to plaster the inside of my cabin walls, straw behind wood lath

[@prplepoppyy]

Thanks will. We are soon clay plastering our hempcrete walls. We have big walls so feel a bit daunted. Just gotta get started.

[@williamstanwix]

I’m sure it will look beautiful, I’ve seen loads of clay plaster by first timers and no matter the texture it still ends up looking great. If you get stuck feel free to give me a shout.

[@schiacciatrollo]

i like cracks for the finish

[@williamstanwix]

Me too! instagram.com/p/CQ5ZjI0sk7l/?igsh=MTd0Yzh0bWZvdmQyNg==

[@schiacciatrollo]

@@williamstanwix thank you .. nice being part of the clay family

[@bendwyermusic]

Why do you need to let the base layer dry completely before adding the top coat?

[@williamstanwix]

The dry basecoat helps the top coat dry quicker and helps you get a good finish. If it was wet it would take ages to finish the top coat as it wouldn’t be getting hard quick enough

[@Shveik1000]

Dear Sir, is that ok to do clay plaster this way on the concrete walls and conventional bricks (ofcause primer first)? Is that ok to put clay coats on the gypsum-plastered wall?

[@adrianfielding4678]

I have done a little of that which you ask in a new cob barn for use as a workshop, studio and small kitchen. The building has been in use 5 years. The finish in most of the building is no more than cheap, homemade clay paint, over two base coats that are similar in constitution to William's (although, based on what I glimpsed of the cob blocks early in the video, I reckon I might have used a bit more straw). It has worked well, notwithstanding the bits that reveal me to have been a novice. Inside, the plinth walls are 450mm thermalite blocks (stone skin outside) topped with mass cob up to wall plate - I used the same clay mix from skirting height upwards to cover all materials, including some concrete lintels. To bridge the interfaces, where differing materials meet, and in a few spots that I dubbed out the most, I used scrim, mainly hessian and synthetic occasionally. Clay is forgiving, if you keep your workspace tidy you can re-constitute surplus and dropped plaster - just wet and remix if it dries. I think clay could work well on bricks that aren't glazed. On a few walls I began a journey with homemade clay finishing plaster on both the clay render/plaster and on plasterboard. To my surprise they have all held up well and the the only material that I have sized, with anything other than a thin clay slip, is some of the plasterboard, on which I used PVA. That is just about okay but not the best; equivalent dings look and are a bit worse when the finished plaster is on the gypsum rather than the clay render substrate. Experimenting, I think I have learned how to size gypsum with clay slip for slightly more durability (and greener cred.) but it requires being quick, clean and organised to time everything ( like cooking a big roast with all the trimmings). However I don't know how to approach a gypsum skimmed and (perhaps) painted walls, other than stripping back to brick. Next winter I will be working on the interior of my current cob project, a house, and I am going to use a wood wool board instead of plasterboard.

[@Shveik1000]

@@adrianfielding4678 Thanks for the sharing your experience!

[@adrianfielding4678]

@@Shveik1000 Have you already done your plastering ?

[@williamstanwix]

Yes you can use it on concrete, bricks and gypsum. Over gypsum and concrete you need to use gritty primer, on soft bricks you can paint a slurry of clay and sand as a primer on hard bricks you need a primer.