The kids and I have been doing a ton of bleach tshirts lately and have found that those darn bleach pens just don't last as long as I would like so after a little internet searching and some "experimenting" in the kitchen I came up with my own recipe.
1/2 cup bleach
3/4 cup baking soda.
I mixed these together in a glass measuring cup and then refilled (rather messily) my used bleach pens. I've already made a couple more projects with the new mixture and it comes out awesome!
Note: This amount refilled three pens but I figured if it was too much I would put the rest in a glass jar until I needed it.