What are the uses of thermochromatic ink?

Answer 1

Thermochromic ink changes color when it reaches a certain temperature. This change can either be temporary or permanent, depending on how the ink's made. The medical and tattoo industries really like this stuff. Both groups use autoclaves to sterilize their equipment. The companies that make autoclave pouches (at least the ones that make them with thermochromic ink) will print the word STERILE on the pouch in a permanent-change thermochromic ink that changes color from blue to black at the proper sterilization temperature, and that's trapped into a non-thermochromic ink the same blue as the pre-change thermochromic ink is. When the hospital gets the pouches, all they see is a blue bar on the pouch. They'll put the instrument they're trying to sterilize in a pouch, seal it and cook it in the autoclave. If it got hot enough, when they open the door of the machine a big black word STERILE will be written right across the middle of the blue bar. I've also heard of people at least considering printing labels for boxes of perishable foods with it. You know you can't leave stuff like meat and milk out of the fridge too long or it goes bad. A thermochromic label would change color if the food was kept out too long to be safe. You can mix thermochromic pigment into screenprinting ink. Remember mood rings? With thermochromic ink you could make a mood t-shirt. Every teenage girl in America would want one.