Do glass shelves affect sound Quality?

All my racks have glass shelving clamped at the sides in 'U' shaped slots.
I added packing to the slots, (besides the nylon clamping setscrews)
Then most of my stuff is on butyl rubber feet (under the stock feet) and/or clamped between the shelves above and below.
I have no problems with using these racks.
The ywere cheap, pretty, and the frame was sand fillable. Which I did.
They are never going to be replaced.
Naturally they are an odd brand i never heard of before, and have never seen in years since i bought the three I use.

Thanks for your responses.

I inquired about Herbies Audio Lab and they suggest using a set of tenderfoot under each component plus a supersonic stabilizer on each component. Has anyone used these products and will they be effective on glass?

Herbie's stuff is very effective. Tenderfeet under my TT, various ISP-cups and blls under my amp & phono stage and a way excellent mat on my TT. I've been using Steve's isolation stuff for years.

MT10425, Thanks for your reply. I'll give the tenderfeet a try.

Does anyone have a response on the supersonic stabilizers?

yes glass is a very difficult substance to work with. I don' like po;ished rock slabs for the same reflective difraction prone properties.
Wood.Rubber and dense metals seem to work great for me