Motion picture film is another product that was initially cellulose nitrate, then was switched to cellulose acetate just as was done with other plastic items like casino dice. The decomposition of the movie film base into acetic acid (vinegar) was given the name Vinegar Syndrome by archivists. The link below is to an article on the chemistry of the decomposition and ways to slow it or reduce its affect on other nearby items.

Basically, store dry and as cold as possible. Keep the items ventilated so the acetic acid dissipates as quickly as possible. Isolate the items that have entered their death throes so they don't spread the poison gas to their neighbors.

Here's something to help you monitor what's happening to your dice collection.

A-D Strips
A-D Strips are dye-coated paper strips that detect and measure the severity of acetate film deterioration, a.k.a. vinegar syndrome, in film collections. The strips are sold in packages of 250 and come with a user's guide (download PDF) and a pencil printed with bands that serve as color references. Price: $60 each for 1 to 9 packages, $48 each for 10+ packages.

You might also consider the use of molecular sieves (the round desiccant devices you often find in bottles of drugs). They absorb water and will help keep your dice in a dryer atmosphere.

Finally, consider the known hazards of collecting casino dice.

- They are easily reproduced so you may not have original items even if the marking looks old.
- Unless you take special precautions, the dice won't survive more than about 50 years.
- Decaying dice can emit gas that will cause nearby newer dice to start decaying earlier.

You may want to scan the hot-stamp images while the dice are still readable and keep them as reminders of what your pile of dust used to look like.