Color changing paint display


We’ve seen several creative projects from [Sprite_tm] and this one sets a new bar. He got his hands on some paint that changes color with temperature. By covering a circuit board with the paint then heating the circuits he’s created a heat actuated 7-segment display (his post is in Dutch). Three seconds at about 1 amp is enough to turn the black paint white. When the segment has been disconnected for about one minute the paint fades back to black. Now that we’ve seen his concept, leave a comment and tell us how you’d use it.


  1. Matt says:

    Oh wow, that’s fantastic. I wonder what kind of color options are possible? I’d be interesting in using it to make similar segmented displays but with non-traditional characters.

  2. octel says:

    Cool project! Reminds me of the stupid “meters” that Duracell used to have on their batteries.
    It was just a strip of plastic with foil underneath, probably the same kind used in those “mood rings”. You’d press on two parts of the battery, the foil heats up, and the plastic changes color depending on how much capacity the battery has left.

    They’re not made that way any more for obvious fire hazard reasons, but the same method could be used for this project without having to put so much current through it.

    Google for “Duracell PowerCheck”

  3. HaDfan says:

    I’d use it to paint my roof.
    absorb heat in winter when its black
    reflect it in summer when its white

  4. threepointone says:

    REALLY cool. true hack =)

    it might be interesting to optimize the on/off times. I’m thinking adding a heatsink and increasing the pulse power will make the on and off times shorter?

  5. John says:


    nice idea i would love to test that in smaller applications like a dog house or something.

  6. phsr says:

    If the off time is about a minute, I bet it would make a really cool clock. Every minute it would heat up to display the current time, and it should fade enough for the next refresh

  7. googfan says:


    great idea

    id use it for a clock. the minutes only change… one time a minute

    a good idea would be to paint it on peltiers. hook them up one way they get hot as a bitch, reverse polarity they get ice cold

  8. Kell says:

    I’d use it to make one of those water traps from Dune, where the changing colour of the trap reflects or emits radiation to promote condensation. Then I could start a career as a water farmer.

  9. sean says:

    @hadfan like the others said, that is a great idea, maybe i’ll try this on a small scale next summer if i remember and have the cash.

  10. Haku says:

    Put a peltier device on the back of it so you can cool it down quicker ?

    That has to be the most energy wasteful 7-segment display ever! I like it :)

  11. googfan says:


    read the comments b4 u post.

    i beat u to the idea

  12. Matt says:

    And if you made the clock with an analog face, you’d get a nifty fade effect as the “dials” moved. Besides art stuff though, I can’t think of anything useful.

  13. charlie says:


    i’d combine this with “paint on” projector screens.

    regular color wall when projector is off, and when the lamp is heating up, the projector screen slowly appears out of nowhere. maybe even do this with a framed painted portrait…that is, if the colors are available.

  14. Marco says:

    Well, peltiers are the obvious solution so don’t be surprised if it gets mentioned several times. This needs to be put into a translucent housing so we have colors instead of just black and white. For frequent changes it’s wasteful, but if you only change it every minute it comes down to an average of 50mA (what’s the voltage?)

  15. License plates :) changing numbers :)
    But there’s a problem… when it’s cold, or very hot :( :( :(

  16. Jacob Woj says:


    Haku said to use a peltier module to cool down the existing installation; nothing about painting it onto 7 seperate modules for each digit.

  17. Mohamed says:

    Cool hack. I cant think of any use yet but I can imagine this concept applied to some board game or something.

  18. kz says:

    Amperage is useless here without resistance. Watt Hours would specify how much energy it actually takes to change the color.

  19. Jack says:

    @Filipe YaBa Polido – Glad I wasn’t the only one thinking about license plates ;)

  20. xrazorwirex says:

    The only flaw I can really think of (for the sake of being critical) is that a major reason you would want to deploy paint like this instead of a display is in a situation where you have it exposed to the elements like on your house or a wall or something, but the major flaw is that if it’s during winter then it would take quite a while to change the display / it might not change at all, and during very hot conditions it might prematurely illuminate…

    …but I love where this is going – I’d like to do something like this with heat sinks to indicate critical temperatures or something. Very cool.

  21. Haku says:


    Can you re-type that in English please?

  22. nave.notnilc says:

    how expensive is this paint, and where can one get it?

  23. nave.notnilc says:

    oops, first google result, eclipse paints, $70 for 4 ounces :\

  24. timbo says:

    living in Chicago, solar powered roof paint – white in summer for cool reflection, black in winter for heating up.

  25. googfan says:


    can u typ tat this way. im sure u can. bcause if u cant, get off de internet. think b4 u speak.

  26. pandaweb says:

    heres some more cool paint by the same company, im assuming. its soft feeling paint

    id love to paint my car black with this stuff

    also, they carry blue to white color changing paint

  27. napalm says:

    Thank you mike, a real hack today, its a good thing

  28. mixadj says:

    Little off topic……Man the flashpoint on that soft touch stuff is low.__________ Cred to guys who posted it first… First thing I though of was clock. Like Matt’s analogue idea. Projector paint sounds kool.

  29. DeFex says:

    I did not know they had this. if paint changed from black to white at 20c (and was durable and inexpensive)) it would be great to paint your house with. absorb heat when its cold and reflect it when it warm.

  30. Getaway Driver says:

    I’d paint my car, and use it to rob places when it’s black, then change to white so the fuzz dont find me…

    You clould probably incorporate this with those other multi colored paints, and different glosses and top coats to get a whole range of colors.

  31. error404 says:

    This sites lack of skill at putting the links in the right places and making it obvious which link is the actual hack is irritating. Why would ‘in Dutch’ link to an English translation?!?

  32. You Can says:

    Nifty! A clock would be kinda neat. Everyone makes clocks, kind of like reminding us how our time is limited, and we should make as much of it as we can…

    Although I usually detest personal attacks, I have this to offer:
    A) “the minutes only change… one time a minute” — I don’t know what you’re getting at here, but I’m pretty sure most digital clocks work exactly like that…
    B) As you can see, the majority of comments actually attempt to make some sort of rational sense, and they spell words out. Thus, you are the odd one out, and as you so aptly put it “get off de internet. think b4 u speak.[sic]”
    C) Please, bury your computer… You can even get someone to take pictures of its funeral and post them on Flickr or something. Heck, I’ll PERSONALLY submit THAT as a hack.

  33. daveatfernie says:

    Ho about mixing some silver heatsink compound in there too and using the paint as the heating element?

  34. suki says:

    Actually it says “1 amp for ~3 seconds”, not “3 amps for 1 second”.

  35. Benjamin says:

    Use the paint as a warning/ heat indicator. Paint it under stove elements, hot water jug, oil column heater, hot equipment or anything that gets hot and could be touched. Could paint “WARNING HOT!” underneath the colour changing paint (because they seem to go from black to clear).

    BTW Alsa also produce colour changing paint that cycles through 8 colours… You could conceivably create a ‘full colour’ photographic display by carefully regulating the temperature on a surface painted with this. Perhaps via a scanning infrared laser or a visible laser shining on the rear side. Or a heat lamp shining through a stencil printed onto an OHP transparency for a simpler setup.
    I also found one of their YouTube videos where they’ve painted a sink which makes sense to me, a bathtub would be good too.

    Also found this: They sell the powder for US$45 which you mix with a quart (about a litre) of transparent base or other paint which is not too expensive.
    Great YouTube video!

    Could paint a light shade with it. When the light is on it warms up the shade and makes it reflective white (or silver), when off it reverts to stylish black.

    Ooh, ooh I’ve just had an idea! Paint black to clear colour changing paint onto glass or perspex to make a cheap window whose visibility can be controlled electronically. Need a way of heating it such as having two panes of glass with an air gap through which you can circulate hot air from a hairdrier or similar to make it clear. Like those ultra expensive LCD windows. Someone should try that, it would make a cool Instructable.

    Or how about interfacing it with optical sensors like a basic LDR with this painted on to make a temperature sensor. Hmm. Are there any applications where both temperature and light need to be sensed at the same time and it could be incorporated into the same sensor? In this case the resistance would be high anytime it is cold and/or dark and low when it is both light and warm. A solar hot water controller? A solar oven? Ultra simple glasshouse ventilation controller – painted LDR in series with ventilation fan and power supply?

    Lots of potential. Thanks Hackaday for this, I didn’t know such paint existed before today.

  36. Tachikoma says:

    Was going to say, 3 A is a lot! Even 1 A seems to be a bit power hungry. Would be interesting to see how it performs if you deposit an efficient heating layer of some sort, maybe carbon tracks, or something equivalent. Pulsed power maybe? Mix the paint with iron filings and use RF heating?

  37. Bahr says:

    Gas station price signs

  38. signal7 says:

    I had forgotten about the color changing paint. I’d like to use it in a current project I have to indicate that the circuit is on … and that my power transistor is hot. It sucks to pick up the circuit and then drop it a moment later because you absent-mindedly didn’t think about the fact that it was on only a few seconds ago.

    @googfan: txt speak only makes you look like an uneducated redneck and it’s definitely not as clever as you think it is. Please spell out your words.

  39. Sprite_tm says:

    Damn, I wanted to make that into a real project (a clock, as many of you already guessed) ‘later’, which is: as soon as I got around to creating a real PCB for it. The paint came from Ebay, from these guys: . The translation is a bit… off, because my post was written in somewhat informal Dutch which Google seems to have problems parsing.

    To clear up a few things: I heated the segment about 3 seconds at 1 amp. The resistance of the traces is quite low, so the voltage over it is too. I think that with a nice buck-converter, it’s possible to get an efficiency which is high enough to let the device function as a clock while not eating into your energy bill.

  40. not really my real name says:

    I sincerely am astounded at how moronic googfans comments are. Almost to the point where I don’t think he has any idea what he’s saying when posts.

  41. mike says:

    most definitely use it as a clock. Align three or four of them and make a sweet clock.

  42. dbear says:

    How about Rorschach’s mask?

  43. Dr. Rembrant says:

    You could easily use it to keep score for the WNBA

  44. MvP says:

    This is AWESOME!

  45. le'chef says:

    How about adding some translucent insulation overtop, perhaps increasing the fade time?

  46. Lawlzdeep says:

    @ dbear

    It’s been done.

    good idea though

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