Do Pre-Mixed Tulip Tie Dye Kit Dyes last months?

The Tulip Tie Dye Kit recommends that you use the dye 45 min after mixing, but I had some pre-mixed dyes sitting in my kitchen for over 6 months.  When I didn't use up the dyes during my first yarn tie dyeing excursion, I couldn't bring myself to dispose of the extra dyes.   I kept meaning to use them, but time was just slipping away.  I finally realized that this would give me an opportunity to test out the manufacturer instructions that the dyes should be used within 45 min of mixing.  Do you think that they would still work to dye a vibrant yarn?

 

I have many other dyeing experiments in my queue, but do you have anything you would like to see me try?  I love suggestions!