Do glass shelves affect sound Quality?

Old automotive engineers used to bury engine blocks to "cure" them. When asked why, they said metal is just a slow moving liquid.

Nice catch geoffkait, Mana was once a very well respected isolation platform. I have two and have never noticed the glass shelves to be a detriment. Though I did prefer a Neuance platform the best under my Sondek Lp12 on Mana’s reference rack, the glass was better than the commonly excepted standard maple block cutting board. So, go figure.

People love to parrot simple ideas/answers like "glass rings" that the real audio world continually proves to those who listen that there just are are no absolutes. 

I use a Bell O' rack w/ glass shelves. I have not noticed any decrease in sound quality. It is heavy, probably not super "heavy" like some of the other racks out in the marketplace.