Blotchy windows

What is this?

@infinity @danthewindowman @dcbrock

Looks like it could be a bad seal on the glass. So moisture gets between the panes.

Were the windows dry in the pics?

Hard to tell from the pics. Sometimes if you’re a pro like me :laughing: you can put your fingernail right over the defect and tell if there is a slight distance between the two, so you know it’s inside or not.

Can’t say for sure, @Grizz but I would start with figuring out where that ‘stain’ is, can you visually see if it is on the outside of the glass or between the panes? Run your fingers over the glass and see if you can feel a difference in texture where the stain is. If between panes, the seal is broken, nothing you can do. If it is on the surface, you can try 0000 steel wool and soapy water, might be hard water stains? Be sure there is no coating on the glass first.


Ditto. Nice to see another window guy on here.

No he said they are not visible when dry only when wet or has dew on them in the morning. He tried ebc to see if it may have been some kind of oil with no luck. The customer had tried cleaning with vinegar and it also didn’t work. I have seen this before but never worried about it.

Its on the outside for sure. Water doesn’t stick in those spots.

Its on the outside for sure. Water doesn’t stick in those certain spots in the pic almost like it has spots of rainx or something. I have seen this on multiple houses but only maybe 2 or 3 spots on larger windows so i figured you guys that do windows everyday see it all the time. He used alittle diluted ebc and brush and rinse just out of curiosity if it would come off with no luck the customer scrubbed it with vinegar and it did work either.

It’s hydrophobic on that part of the glass.

Nothing power washing did.


Small piece if fine steel wool, a dab of dawn and should come off if not a defect or opposite side if pane.

Other than whats mentioned, what about a foggy high up window that mix may have caused, but didnt touch it days later. Rinsed the heck out of it, but the SH was weak. Better SH?

Some bronze wool and a mild abrasive to possibly remove whatever is making it hydrophobic. Not a sure guarantee.

But really only if they care and you care.

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It wasnt a house i did this was someone elses job i was just curious because i have seen thus before but not i know what to do if a customer blames me and forces me to fix it. Thanks for the info.

No telling what that is. Brick sealant, post-WC wax job, Rain-x…I’ve seen way too much crap over the years.

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