"therustyone" wrote in message
...
Fixing an old broken pair of specs with epoxy it seemed a fantastic idea
to accelerate curing by sticking them in the oven at 45 deg. C for half an
hour.
While this certainly cured the glue, I noticed very slight crazing of the
anti-reflective coat for certain angles of light, just like you get on old
glazed pottery. Not sure if this was there before, and it hasn't visibly
affected their optical quality.
Searching on the web I found this is a little-known problem caused by
differential expansion. Bloomed specs should be kept cool, for example not
left on the dashboard in the car in the summer sun.

Never had any problem with my sunnys left in the bin and the radio and we
can have 10 days in a row over 100F and the car is quite a bit hotter than
that.