[vivaro 013]

ive been ask to quote to clean some windows , customer informs glass windows are very old he feels the glass is brittle , any body heard of this before and what to watch out for

[AuRavelling79]

Old glass can certainly be thinner and can be untoughened (and thus weaker) but as for "brittle" I'm not sure.

[craig jwc]

Before my mother had new windows and frames put in her house she was told that the glass that she had was called Picture glass and was put in during the war.

This was really thin and had to have one replaced when i was a kid when a bird flew into it.

If you pushed very slightly on it you could feel and see it bow.

[Paul Coleman]

ive been ask to quote to clean some windows , customer informs glass windows are very old he feels the glass is brittle , any body heard of this before and what to watch out for

Some old houses have glass like this.  I cracked a pane once by pressing too hard on a Victorian house that looked like it had original glass (trad method).

[jeff1]

ive been ask to quote to clean some windows , customer informs glass windows are very old he feels the glass is brittle , any body heard of this before and what to watch out for

I was in the security alarm engineer for 15 years, and installed a lot of breakglass detectors,(BGD) and the latest technology in BGD was one that listened to glass,
Glass does flex when you press against it, when it flex's it also makes a noise, and modern detecters can hear the noise of flexing glass, then it puts the detector into alert mode, it then opens a time window, if the glass is then broken(again a different noise) within this time window it will then activate the alarm.
The thinner the glass the quiker the BGD would go into alert mode, Flexing glass means its about to break.

Your customer is right to alert you, to the fact that the glass is Brittle,and its just a way of warning us that the glass is very thin. so be warned wash very gentle.