How your Thermochromic pigment change colors ?

How your Thermochromic pigment change colors ? 

Normally customer ask us to make the blue color change to colorless extractly at 20℃ 

But theoretically speaking is that for the thermochromic pigment, there is a ativation temperature . and a color changing temperature period of 5℃ to 7℃.  in this case , activation temperature of 5℃ (up to 5℃, the color is dark blue, above 5℃, the color decreases and 20℃, it becomes colorless. 

And the fact is that for the thermochromic pigment, there is accepted small temperature errors ±2℃ which could not be avoided.  in this case the ture is : activation temperature of  5℃ ±2℃    (up to 5℃ ±2℃, the color is dark blue, above 5℃±2℃, the color decreases and 20℃±2℃, it becomes colorless.

Summary, at 3℃ or5℃ or 7℃ the color is dark blue, above it, the color decreases and at 18℃ or 20℃ or 22℃ it becomes colorless.  

What we could do is do best to make it as close as possible to your accepted color changing temperature period :)