AIBU to paint south facing windows with chalk paint as a temporary shading hack?

[JennyForeigner]

Just curious. I was reading an article on solar shading and was surprised it doesn't mention good old fashioned limewash, or the modern equivalent - chalk paint.

I've got a garage full of Annie Sloan, which I already use on a bathroom window to obscure it. A very quick bit of research says painting the exterior of my south facing French windows with chalk paint would cut absorbed heat by up to 90% compared to 40-60% for closing the curtains, and would wash off at the weekend.

Obviously I would recommend it as a solution for people in upper story flats or anything, but have I hit on a genuinely affordable and useful idea? How to shade your home

Take care with this. We’ve done it in the past too, but in the last heatwave the foil oxidised and left a burnt on residue on the windows that we’re struggling to get off.

Bugger. Thanks for the warning. I peeled a bit off just now and all was well, but I'll keep an eye.

That´s why we have persian blinds on windows in Spain. Mine are down when sun on windows. My husband forgets and when I got home yesterday the house was 30.6 C inside in the evening. It makes a huge difference.

Down a rabbit hole of looking at Japanese, Chinese, and Indian paper, fabric, and carved wood or bamboo folding screens.

An indoor carp pond and some tall deep green fronded plants in terracotta planters would also be cooling.

Any luck getting it off?!!!