I am just about to finish construction of my RMH and I am trying to look into the best option for plastering. (Best being easiest to do with easy to find supplies.) It is in my greenhouse so it will need to resist moisture fairly well.
Also, I'm assuming that everything is going to have to be very dry prior to being plastered....so it may be a while before I can do that part. This is my first RMH and I've never mixed a plaster before.
As for me and my house, we will serve the Lord. Joshua 24:15