Are UV rays damaging LS membranes?

[Infobert]

Hello, I have positioned my 40.1s (without grills) close to a window. For some hours per day sun is shining directly on the front of the speakers. Is this a problem for the membranes of the speakers? Do the UV rays damage the membranes? Thank you

{Moderator's comment: yes I would expect the UV to attack the cones and surrounds. The recommended use (as per the User Guide) is grilles should remain fitted.}

[hifi_dave]

Definitely not a good idea in my experience, with any speaker.

Personally, I would leave grilles on and draw the curtains or close the shutters. Don't leave them to be baked in the Sun.

[A. E.]

not only the elements covered by the grilles, but also outer veneer doesn't like direct sunlight...

But, is it really UV that ruins them? Because, almost 90% of the UV is already blocked by ordinary window glass...

[Infobert]

Thank you for the replies. I will go buying curtains...