I actually did call and talked with ProChem. They said the shelf life is about 2 years. My dyes were stored in a cool place, so I expect that is why some of them seemed ok. I did experiment and few gave me good color and saturation, but your thoughts about the stabilty of the color is intersting and something I had not thought about. So, that being said I think my experimenting is over for now and I've ordered some fresh dye powders. Thanks!

Calling the manufacturer will definitely be the best course of action. You don't say what type of dye powder they are. My fiber reactive dyes from Dharma are said to have a shelf life of about a year, depending on how they were stored. Heat will cut the life of the dyes, so if they are stored somewhere that gets hot, the time is less. If you have dyes that old, I wouldn't use them on anything you cared about, but I would probably play with them if you have spare fabric. My main concern would be whether or not they were stable on the fabric. The way these dyes work is by creating a chemical bond with the fabric, they actually become part of the fabric through the dye process. If the age makes that bond unstable, you may find the color doesn't last. And as you noted, you may find the color just plain unpredictable.

But if you have extra fabric and time..why not just play with them?

To be safe, call manufacturer.

I am getting ready to hand dye some fabric, but I am questioning the stability of my dye powders. Some of them are 5 -6 years old! (I thought I just bought them yesterday!) Last year I dyed a few pieces of fabric and it seemed like the yellow kind of got lost and I ended up with a lot of orange shades of fabric. Does anyone know what the self life is of these powders? Will I still get a good saturation if I double or triple the amount of dye concentrate? How long are the powders stable? So many questions,...
Thanks,
Cindy