I really enjoyed reading this, I am still hoping for a red barn of my very own. For now I'll just keep painting other things red :)
We've had great success using milk paint both indoors and out. It's standing up really well on our outbuildings and on the furniture that I've painted. The milk paint that I've been buying contains milk protein (casein), limestone, clay, chalk and natural non-toxic pigments made from iron oxides. It's amazing stuff especially if you want to avoid the use of paints that emit unhealthy fumes. I know some of the more trendy "milk paint" products aren't really holding to the traditional recipes anymore.
I'm interested in using slaked lime and water in the spring to paint the inside of the chicken coop. I've read that this has antibacterial properties. I would love to know if anyone else does this and what they think.
You can make your own Milk Paint, using skimmed milk, mineral oil or jojoba oils, rust or red sand, and lime. There are a bunch of good website that have the recipes. Give that a go. I don't know much about slaked lime for painting. Sorry. Thanks for reading.