What's happening to my rear windshield?

[atldohc]

Can anyone identify these brown spots on my rear windshield? I've only noticed them in the past month or 2 and they dont appear anywhere else on my car. They appear to be rock hard bubbles and when I scrape them off with a razor they leave a crater behind. My first guess was maybe it was overheating due to the rear defrost being left on, but I havent left the button depressed. I checked for power with a voltmeter and it works correctly, with 12v at the driver side spade connector with the button turned on, and no voltage with it turned off.

[ELVA164]

Is there anything that could be landing on the glass?

[Das Delfin]

how long have you had the car? It's possible you just never noticed them. Either way if they aren't on the body of the car or any of the other glass panels, there must be something about your rear glass.

What's also interesting is the lightish opaqueness of the glass around each spot. Almost like the brown spots were hot when they appeared on the car. You don't think it's from all those fires in GA?

[atldohc]

well ive had the car a good 8 or 9 years atleast now. i definitely would have noticed it within atleast a few months since i wash the car and do all the other work to the car myself. i suppose it could be fire related although the closest proximity ive had to them is seeing some slight smoke haze in the distance, and its not anywhere else on the car. i guess it may be one of those things ill never know for sure. for now ill just try to monitor it and see if it gets any worse.

[redsportt]

spots

loks to me like a grinder has been used in the vicinity of the screen and some molten sparks have embedded into glass which have now rusted

[Mediumrarechicken]

There is no way the defroster gets hot enough to melt glass. That's odd, was your car around welding or fireworks onn the 4th?