Dry wall mud dries hard as nails but breaks down fast using white vinegar.
also, we use painters 5 and 1 tools for scraping frames. Keep a supply of green pads bought from the janitorial supply store nearest you. dont touch the glass...it will scratch glass fats! But for paint, stucco and dry wall mud, green pads and goof off are da bomb!
for the last 14 yrs i have tried many ways to deal with this. the best that works for us is spray around frames with straight water, take a 1" scaper knife and run up along sides and across the top for clean edge. everything else will wipe off with a sponge. may take a little practice to use a razor knife without knicking frames but takes 2 minutes per window to knock off mud once you get used to it.
As for the razor... go to your local auto parts store and order and inspection sticker scraper. Has a nice adjustable hand for angles and allows you to control pressure. Otherwise I use a plastic scraper and vinegar.
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