The painted red strip around the outside of Roman Buildings

[Aetius Helvius Merula]

I see it's been a while since anyone commented on this, but I'll try:

I don't know how much of this applies, but I've been told that the dark red paint that's traditional on barns in America was originally composed of milk and blood from slaughtering animals. It was plentiful and it preserved the wood. The Romans didn't drink nearly as much milk as Americans do, but I wonder if a chemical analysis of the residues of red paint might show it to be blood-based...?

This seems like a huge amount of a food product to waste by throwing it on a building.