Terminology question

We have a whole bunch of old color prints of various sizes lying around and (even in albums, shielded from light) fading.  

I have the photographic equipment at hand (DSLR with a good macro lens and a sturdy tripod) to photograph the prints and thus digitize them — except for one essential piece.  

When laid “flat,” the prints are not flat.  They bow and curl.  They are also affected by slight breezes (like when I exhale) and static electrical attraction.

I cannot afford a vacuum hold down device, but I am pretty sure that I can afford a very thick (to make it massive) plate of flat glass, preferably frosted to reduce surface reflections.

I know that type of accessory exists, but have worn out Internet search engines trying to find one.
How (search terms) would you search for one?

A quick search yielded dullesglassandmirror. Dot com/frosted-glass

Technical terms would be optical glass or crown glass.. can get expensive though, and might be a bit of overkill for your applications.

Also; a quick google for homemade vacuum tables shows that something small can be made with limited tools and a limited budget. Vacuum can be provided by a, uhm, vacuum. A hoover, as the Brits would say.

non reflective glass is used in framing paintings and photographs.