Quote Originally Posted by Thomas Bertilsson View Post
Unless you use powder, of course. I had some Kodak DK50 in 2011 that was from the 1970s, and it worked fine (obviously). Right now I'm using some D76 from the 1980s, and that works just like the new stuff you buy today.
Another data point: some years ago, a large local camera store was downsizing and sold off all its darkroom inventory. I picked up an ancient, rusty 5 gal can of Dektol powder. I immediately separated it into a number of small glass Mason jars. The developer works fine, if I'm printing fast enough. If the stuff sits in the open jar for a couple of weeks, it turns quite brown and I toss it without trial. Unopened jars maintain their original color (more or less, I suppose).