Sick glass? Maybe this will work for you.

[Paper Roses]

I never had any luck curing sick glass. Tried everything I could think of through the years.
Two weeks ago, as I poked through the 'free' box at a local thrift shop, I found a cut glass decanter. The glass was is great shape but very sick. Rather than let it get chipped or broken, I took it.
Since over the years I have tried almost everything in my supply of cleaning stuff, I decide to do a quick test with a product I recently bought at "Dollar Tree". Nothing to lose. My purchase was for other reasons but I thought I'd give this a try.

The spray is called "Limax" and cost a dollar.

I washed the exterior, and followed the instructions on the bottle for general use but did the following:

I sprayed the inside of the decanter generously with the product, enough to make a good size puddle on the bottom, rotated the decanter to cover all surfaces, then added about a quarter cup of raw long grain rice. Needed to have some kind of mild abrasive to help scrub.
The instructions for use on regular items calls for the product to sit for 20 to 30 seconds.

I immediately started to shake and swirl the rice around in the solution. I think I did this for about a minute. Not sure.

I then drained the solution onto a strainer(no raw rice should go into the disposal, and rinsed the bottle.
Since sometimes, sick glass looks good for a few days and when it dries, it looks horrible, I put the decanter aside. It has been two weeks and nothing has reappeared. It looks like new.

This may not work for things you have but for the dollar I spent, it is a big plus.