Color changing

Yet another <strike>lame, cheesy</strike> awesome gimmick in the fight for toy dollars is the ability for a toy to change color.

Generally this is done by application of paint or a sticker which contains some sort of color-changing ink or paint. This color shift is brought on by the power of love and a positive, can-do attitude, but the heathen scientists, whose <a href="http://en.wikipedia.org/wiki/Mood_ring" class="extiw" title="wikipedia:Mood_ring">mood rings</a> never worked, have other explanations, which will be given for the sake of humoring the unbelievers.

This color change is usually linked to temperature, and is called a thermochromic quality. An early thermochromic substance, liquid crystals, found use in Transformers rubsigns. Later, color-changing leucodyes were invented. Excluding rubsigns, a Transformer with color-changing features probably uses a leucodye.

Leucodyes require a temperature shift of about five to ten degrees Fahrenheit.