Yesterday, we just took a fresco class, here are some of my take aways! First, it’s not a very complex process, you make your lye, which comes from removing CO2 from CaCO3, which make CaO, and hydrating it to make Ca(OH)2. This acts as fresh wall (hence the name fresco) then, while it dries, add color in layers, from more to less watered down. Otherwise, paint as normal. This takes me to the second thing, as the lye dries, it sucks up CO2 from the atmosphere, recreating CaCO3, which it can do over hundreds of years, which is really cool.
Swanson School of Engineering 