"George" wrote in
news:_NUOd.51485$4I2.24351@attbi_s01:


snip If it
was me, I'd use the vinegar. Have a little patience with it, as it
takes a little longer to work. But it does work well.



I used vinegar and it worked. I still needed the razor blade, but at
least it came loose this time. I used a 50/50 solution of white distilled
vinegar and water. Soaked paper towels in it, and laid them on the
affected areas (only one layer deep). I let it sit over night. In the
morning it was all dried. And I scraped it off, with a some effort. I
suppose, more vinegar may have helped more,

One thing I have noticed is that in the areas of the most coraline crust,
there are definite marks on the glass that I cant remove. I did a whole
nother vinegar treatment just on these marks, and they dont move at all.
Not with a sponge, or a razor blade, or anything. I dont even feel
anything there with the blade or by touch. But the marks remain, looks
similar to waterspots. It really doesnt matter, because they're very
subtle, you have to look for them, and they're all on the back glass, so
inconsequential. But it makes me wonder it the coralline actually etched
the glass itself.