To most whitewash is a derogatory term.....even when talking about the real thing. That's really too bad. It's a great old technology....with many uses/advantages and very environmentally safe.

And it even pulls CO2 out of the air.

https://en.wikipedia.org/wiki/Whitewash

 

Never heard of the derogatory use, other than to cover up something. I always thought of it as a type of paint, if I thought of it at all.

 

"never heard derogatory use"!?!?!?

(and this from a "moderator"?!)

It is frequently used to describe incomplete and favorable descriptions of conditions, to present them as good or acceptable, where there are known faults/deficits with those conditions. I believe Merriam Webster uses the example of concealing corporate wrongdoing.

The actual compound known as Whitewash is simply a suspension of lime or gypsum particles in ordinary water. I'm not a chemist, but I don't see much CO2 impact there. It would take quite a bit to reflect much solar energy.

 

Source: Somewhere on the internet
Lime mortar does not require water to grow crystals, cure and get hard like cement based mortars. Limes get hard by absorbing carbon dioxide from the atmosphere. As such, you must add only just enough water to make the mortar workable. Mortar can be mixed by hand or in a modern cement mixer.

And here (of course): https://en.wikipedia.org/wiki/Lime_mortar

How did I know that? My home in Cleveland is older and is brick with lime mortar and lake sand. It needed some repairs. Mortar needs to be softer than the bricks it holds together. Lime mortar fulfills that need. Later at my hobby farm, I had problems with burrowing animals, mainly groundhogs. So I read up on mortars and "soft" concrete (as is used for barriers at toll booths). I wanted something to put around the base of my barn that would stop the groundhogs, but not destroy my mower when I hit it. Played with lime mortars, crushed limestone, sand, and a tiny bit of cement (1 shovel per 12) to come up with my special mixture. It sets quickly, even in damp areas and remains soft enough that a shovel will cut it. No ground hog burrows since then.

Back on topic, while white wash does absorb CO2, , I suspect the amount you exhale while painting a barn balances out the amount absorbed.