A cheap idea for thermal imaging

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Sometimes I needed to check how heat was distributed on a surface. A cool but expensive way is to use a thermographic camera. I do not have one at hand.

But an ongoing project uses thermochromic ink. That is an ink that becomes transparent once a temperature threshold is reached. It goes from a certain color to no color at all. So if you paint a piece of cloth and place it on a given surface you can do the measurement of temperature at each point.

The following pictures show the heating process of a certain aluminium heated bed. My sample cloth was not large enough to cover the whole bet but you get the idea.

 Heat sources start to show as whiter areas. 

 Now heat spreads a bit more.

 Reaching the temperature threshold at many points

For best results a glass on top would make sure the cloth is making contact with the whole surface evenly (top left corner was not having a good contact which explains the apparent colder temperature).

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