Science Buddies: "Ask an Expert"

I have to test the pH levels in 3 different brands of purple liquid fabric dye. I am assuming that the most acidic dye will bring out the most vibrant color in fabric. I am using strips of white t shirt and dipping it into the different brands of dye. I don't know where to find test strips to test the pH level in the dyes. The strips I have found would not work because the dye would turn the strips purple. Does anyone have any ideas?

Hi Fleming,

This is a very interesting problem. pH strips are all based on a color change of the indicator dye that is contained in the paper. Your purple dye will always interfere with the reading on any type of pH paper. You need access to a pH meter that will give a reading based on a voltage signal. I recommend asking your teacher for a suggestion, or contact a local high school, university, or local laboratory. I'm sure there's a pH meter available for you to borrow for just a few samples.

Good luck!

Donna Hardy