Tldr; Wet newspaper dipped in ashes.
So, the other day I had to clean out the fireplace, and ofc the fireplace window(glass) was rather dirty. Tried for a while to get rid of it with paper, then scrubbing it off with a one-time-use sponge etc… nothing gave any good results.
Then, I came across this random video online of a woman who said to use wet newspaper dipped in ashes from the stove, and start scrubing - This works like a charm! Forget all expensive chemicals and soaps to do this job, just KISS! Keep-it-simple-stupid.
Please give this a go next time you have to clean your wood-burning stove.
A lot of folks don’t have the old knowledge that wetted ash burns you. It’s actually the Arabic base of the word “alkali” and was historical common knowledge that we’ve lost. How bad it can be depends on the plant, but there’s cases of people using popular ash and occluding it in folk remedy and getting pretty deep scarring burns. It’s what we used to use to tan leather and make soap, after all.
Edit: Sometimes it results in pretty funny incidents though:
https://www.bbc.com/news/world-europe-26478900 (the chemistry in this article is completely out of wack. Generally it’s potassium carbonate that you’re creating with ash. You’d need to add slaked lime [lime dissolved in water, calcium hydroxide] to potash/potassium carbonate to make potassium hydroxide and calcium carbonate [chalk]).
https://www.ucanews.com/news/philippine-bishop-orders-probe-into-ash-wednesday-burns/81551
https://www.reddit.com/r/Catholicism/comments/7xia9n/help_my_church_added_too_much_water_to_the_ash/
https://www.foxnews.com/lifestyle/ash-wednesday-worshipers-in-colombia-hit-by-mysterious-burning-rash-on-forehead
What a mystery. And it only seems to happen in churches that use water for ash wednesday, never oil.