Calcium Bloom

[Tdawg]

If razor blade won't get it off on glass then it is something else, not calcium carbonate. I can't think of anything that I cannot scrape off glass with a razor blade.
ANYTHING CAN BE SCRAPE OFF GLASS WITH A RAZOR BLADE SCRAPER, UNLESS IT IS IN THE GLASS.

Hmm

 

[Tdawg]

If razor blade won't get it off on glass then it is something else, not calcium carbonate. I can't think of anything that I cannot scrape off glass with a razor blade.
ANYTHING CAN BE SCRAPE OFF GLASS WITH A RAZOR BLADE SCRAPER, UNLESS IT IS IN THE GLASS.

So, I stand corrected, I can scrape it with a razor blade, but it seems to come back Ina couple of hours.