If mortar from bricklaying is spilled and allowed to dry on glass window surface does it etch, damage or bond to the glass and/or is there a way to clean the mortar without damaging the glass?

I've heard you can use a blade and also you can use an acid cleaner, like phosphoric acid, to help...

Id call a local masonry shop, might be under masonry, might be under landscaping, and see what they recommend. The two in town here are run by guys who were masons, worked in the field, and now just buy and sell materials. I've always had great advice from talking to the mason supply houses.

Or wait here... there are some great construction people here wholl chime in once they see the thread.

Crystal Clear 550

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Where do you find Crystal Clear 550? I've never seen it

Only if you scratch it while removing it