Blackboards were often real slate. Chalkboards (note the different name!) were wood painted green. I don't know why the name was different, but that is what I always saw.
Comment on Blackboards were the OG dark mode
reddig33@lemmy.world 3 days ago
There was this strange fad of repainting blackboards to green in the early 80s, because someone thought white text on a black background was causing eyesight problems. I don’t know if that actually turned out to be true.
bluGill@fedia.io 3 days ago
oce@jlai.lu 3 days ago
I couldn’t find any reliable source, but the most convincing idea I read was to reduce contrast and glare issues between the white chalk and its background. The green would reflect more light than the black, reducing the contrast and the glare. Also, the original blackboards were made of black slate, but then they became synthetic which made it easier to change the color.
Axolotl_cpp@feddit.it 3 days ago
I don’t think it’s true but it’s real that ir may give problems to some people (especially astigmatic people) but
Perspectivist@feddit.uk 3 days ago
It was actually just that the world was black and white before that.
prettybunnys@piefed.social 3 days ago
exactly, they were always green, but since the world was black and white some of them went cheap and put up a black board instead of the proper green.
When the world switched to color the black ones often were repainted.