Discharge ink has a “pot life” of only four to six hours. Once you add the discharge agent, the chemical ZFS that makes the shirt discharge, you can only use that ink for so long before it no longer will discharge.

Two tricks that help with this.

1. You can mix up all the colored ink you need, but wait until the last minute to add the discharge agent. If you have a super long run, only add discharge agent to the amount of ink you will use the first day.

2. That discharge ink works absolutely fine as just plain water-based ink for white shirts once it doesn’t discharge any longer. So print your darks first, then even if the ink has “gone bad” it will work on white shirts, you can even save it in a closed container for months, just be sure to mark it as water-based ink, NOT discharge ink.

Here you see a black shirt nice and brightly discharged to the Amnesty International candle in yellow. Two days later we were still able to print the white shirt with that same yellow ink even though it had lost its ability to “discharge.”