I helped run a tie-dye activity at my other daughter's Galileo camp today. One of the kids managed to get me with the dye today (not on purpose).
Here is a vivid demonstration on the importance of wearing eye protection (such as goggles, glasses, sunglasses, etc.) while doing tie-dye, even if you are not the one doing the dyeing (but especially if you are).
Here's the picture of where my face got hit by the dye. Good thing I was wearing my sunglasses! I wiped several drops of dye off of the sunglasses.
It's important to provide eye protection for the kids, even though it's a pain... the pain in the eyes is worse! And when you are working by yourself, you should still wear protection: squirts happen!