I have some Gold Chloride which is years old. No real shelf life.
You need to know that the "regulations" force manufacturers to put a "shelf life" on almost everything, regardless of utility, and that the manufacturers are only too eager to comply because they hope that you will throw away perfectly good chemicals and then buy some more. Very few chemicals degrade in storage.
For instance, honey (that is, the real stuff, not the pretend versions sold in some places in the USA) has to have a shelf life on te jar in the UK/EU(SSR); but honey, seeds and other things have been found in rock tombs in Egypt and have been perfectly edible.
Lt Col Jeff copper (of Gunsite fame) used to opine that if you wanted to store a handgun for many years, select a revolver and bury it in a cave (even temperature during the daytime) in the high desert (vv low humidity) with a box of ammunition. After fifty years, he felt that it would be fairly likely that the weapon could be loaded and fired without further preparation. In 1980, I myself was given a dozen rounds of .45ACP Tommygun ammunition when I was in the Army that could not be returned to storage. It worked perfectly despite the date on the headstamp of 1944. The ammunition was from Royal Marine Commando stocks sent to RMCS Shrivenham after the Second World War.
I would bet that the actual shelf life of most chemicals would be well in excess of 100 years. Only Noah and Methusalah would need to be careful about rotating their stocks.
P.S. My thanks to the USA for their Tommygun ammo via Lend-Lease.
