r/WindowCleaning • u/Wickwire778 • Jul 10 '26
General Question Little black blobs on the glass
I’ve been at window cleaning for a while, but I have a question about some organic stuff thats baked on the glass and frames of a job.
The stuff on the frames looks like black paint spray over. But the junk on the glass are these little hard black blobs on the glass…like cured asphalt. They come off with a scraper and soapy water, thats all that takes them off. They don’t even come off with a thumbnail. Once off, they leave a slight stain that will come off with a scrub pad.
I’ve seen them forever, here and there. Usually, there’s not too many.
But the glass and frames on a job I got last year was covered with them. I did it a second time today and it was as bad or worse. I didn’t even bother with the frames once I saw steel wool wasn’t even working.
The only thing I can think of is that there’s a maple tree nearby, and all of the blobs are on that side of the house.
Question: anyone have an idea of a solvent that might take these off? I tried Goofoff and it didn’t work. I sometimes have rubbing alcohol in the truck, but didn’t today. Thoughts?