AR70 - which side faces out?

[WannabeFramer]

I have previously bought AR99. museum glass and and TruView Conservation Clear cut to size, and each had a sticker saying "this side faces viewer".

I am now cutting my own glass and have some AR70 to cut.

The website says
"......it can be cut and glazed from either side and its coating is scratch-resistant and very easy to clean."

Just double checking it really doesn't matter? One side isn't more durable 'outside'? I can't actually tell a difference to each side holding it to the light.

Thanks!

[theframer]

Any side is fine

[Justintime]

It's only UV99 and AR99 that have to be cut and facing a particuler side.

[WannabeFramer]

Fab, thanks both.

[JKX]

It's only the stuff with the absorptive UV coating on one side that should be scored and presented on the opposite side, and it will always be marked to show which side that is - bar some of your own offcuts that is of course.

The way to test if in doubt, is "the scratch test" - scratch a corner with the point of an awl or something - not something so sharp it would scratch nornal glass anyway. It will skip over the uncoated side and leave no mark, but on the coated side you'll feel resistance and it will leave a mark.

Affected products are Artglass 99 and Artglass AR 99, Tru Vue Conservation clear, Conservation reflection control and museum.

All of the above mentioned BTW, are, as far as I'm aware, the only single layer glass products that meet the ISO for conservation glass, which states it must filter at least 97% of UV within a certain range, absorptively (as opposed to reflectively). Anything lower cannot (well, SHOULD not) be called conservation glass but can of course be called "UV glass" - even when the UV filter is an unintentional and pretty ineffective feature of an optical coating.

[WannabeFramer]

Thank you, much appreciated.