Paint or die that changes colour with heat??? please read and help!?

Question

I am looking at making something, but i need to find out about a dye, plastic, or paint etc. that will change colour when i pour boiling water onto the other side of a piece of glass or plastic.

I know that it exists as i have seen toothbrushes that change colour when being used. Please tell me where i can find out about these products or what they are called.

Any ideas???

thank you!

Dylan

Answer 1

Thermochromism is what you're talking about. The two common approaches are liquid crystals and leuco dyes.

Thermochromic paint is a relatively recent development in the area of color-changing pigments. It involves the use of liquid crystal or leuco dye technology. After absorbing a certain amount of light or heat, the crystallic or molecular structure of the pigment reversibly changes in such a way that it absorbs and emits light at a different wavelength than at lower temperatures. Thermochromic paints are seen quite often as a coating on coffee mugs, whereby once hot coffee is poured into the mugs, the thermochromic paint absorbs the heat and becomes colored or transparent, thus changing the appearance of the mug.

There's plenty to see in the link below.

Answer 2

Only place I know of, listed below.