Mad Science Test Tube Rack

by John Park

published October 17, 2016, last updated October 17, 2016

posted in LEDs Feather

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Intermediate

Project guide

Mix the Potions

It's mixing time. Be careful when working with the pigment not to breathe any of the very fine powder (wear a mask or respirator), and work on a surface that can be cleaned, such as a wax paper covered workbench.

Wear nitrile gloves to keep the dye off of your hands, and mark your containers as "not for consumption"

It only takes a very small pinch of powder per test tube. You can mix the pigment and water in each test tube -- use a stirring rod or bamboo skewer to thoroughly mix it, or place a stopper over the top, cover the hole with your thumb and shake it like crazy.

If you plan to use the same color in a number of test tubes, premix a batch in a measuring cup, mason jar, or beaker and then pour 50mL per test tube.

Shine a UV LED into your tube to see the effect!

If there's too much pigment, the tube will not glow internally, only on the surface. In this case, add water to dilute your mixture.

The pigment is suspended in the water, so you may need to occassionally shake it up to redistribute, or mix in a tiny amount of an emulsifier such as xanthan gum (available in health food stores and online) to keep it in suspension.

As an alternative to pigments, the ink from many highlighters is also UV reactive.