1. Overview {status = in progress}

Thermochromic inks are slowly becoming more and more available outside of the industry and are getting into the hands of the makers and crafters. There are still MAJOR challenges related to electrical control of thermo inks -mostly relatated to power and battery short circuiting. (Any help on that front would be great).

2. Materials

• Special Inks
  • Most commonly available from Chromatic Inks Technologies. These inks come already mixed and ready to use.
  • Matsui International also sells them but they are harder to obtain in small quantities but you can get samples and the quality is much better. You have to mix these inks with binder and fixer provided by the company.
• High resistivity Thread
  • Best results from Bekaert, series 14VN series
• Regular fabric ink (optional)
  • Can be found at any art supply store, Speedball is one typical brand

About the inks

The inks go from color to a dirty white when heated. They don't actually appear or disappear, just change color. Adding a regular fabric ink will color the white so that it becomes a light pastel when the mixed ink is heated. It is possible to give the illusion that the color is actually appearing when heated by printing on a fabric the color of the raw, unheated ink: when heated, the print would then appear in a lighter color (usually pastel or white).

It seems that diluting the inks a lot will allow you to use them as dies and might even give better results when trying to create a disappearing ink effect.

3. Skills required

Silkscreen or some form of fabric printing method
Basic Circuitry building (depending on the application you want to create)
Soft Circuits

4. Instructions

A--Prepare your ink and your fabrics first.
Most thermochromic inks go from full color (cold color) to white/grey (hot color) when heated. You can color the white/grey state by mixing in a little bit of standard fabric color. However, as you color the raw ink, your original cold color will also be altered so play around until you get the results you like. Print on the fabric using your preferred method.

Some inks require preparation first

Prepare and label your mixes

Prepare your fabric

Use screen mesh no smaller than 160

Or apply ink using cutout patterns

B--Add the electronics
Stitch conductive thread where your print it and where you want color changes to occur. The thread will constitute the core of the electronic circuit. Depending on the resistivity of your thread (higher is better), it will heat up (but not burn) as it dissipates power and change the color of the inks around it. This technique remains limited and we are still looking for appropriate ways to power the thread without eventually damaging the electrical supply.

Hand or machine stitch

Test the thread and color changes

Find the appropriate power source

Build your circuit from inside

This is the effect we are looking for outside

5. Estimated Price

6. Estimated Time

Printing should take up to an afternoon. If the inks you are using need to be mixed before hand, allow an hour for this to be done first.
Circuit making depending on how complex you want this to be should take at least a day.
Testing and finding appropriate power supply or battery will take you a while.

7. Possible Applications / Projects using this

8. Credits

Joey's resource page (ask for permission to link)
Sonali and Mouna's work

9. Variations

Use other sources of heat whose power consumption is known like:
Pelletier
Heat belly thing

10. Comments