Heat sensitive paint

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Heat sensitive paint

Postby Harry Dalek » Sat Nov 18, 2017 9:23 am

After chatting with Keith on if it were possible to use heat sensitive paint for a mechanical sstv screen i have found my ruler that has the heat sensitive paint .

Now I don't have a IR laser handy to try but i did have a copper American coin and a way of heating it with a soldering iron for a sec.

The experiment must show that the coins area shows up and the paint around it stays at room temperature showing a clear out line of the coin ...the paint does change shade depending on temperature which here on this go its only really 2 shades due to this primitive test .

I did notice a very ruff outline of Abraham lincoln's head out line in one go .

With the correct IR laser power and this stuff painted on screen might be a goer ...unlike glow paint the image does not seem to blur as if fades .

BTW i tried an unused glow paint tin and put my soldering iron tip close to it and the effect of the extra heat on the charged paint area was a brighter area not a decrease in Phosphorescence so there must be some difference to IR radiation or heat really to different glow paint types ...
The phone cases here would be a good cheap screen for experiments my only problem with the idea is fading the image does hang around longer than glow paint unless you can cool the area perhaps great for 72 sec b/w or the longer SSTV or fax line rates....
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Re: Heat sensitive paint

Postby Robonz » Sat Nov 18, 2017 11:46 am

Good stuff Harry,

I think it might work better than i thought. A couple of ideas for you while you are in Dalek science mode.

If you wanted an IR laser, those laser printer polygon mirrors normally have an IR laser in the mechanism. Did you try the UV laser to see if it could engergise the heat sensitive paint?

To quench you could simply try a ducted fan to blow and cool down the heated area.

Cheers
Keith
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Re: Heat sensitive paint

Postby Harry Dalek » Sat Nov 18, 2017 2:56 pm

Robonz wrote:Good stuff Harry,

I think it might work better than i thought. A couple of ideas for you while you are in Dalek science mode.

If you wanted an IR laser, those laser printer polygon mirrors normally have an IR laser in the mechanism. Did you try the UV laser to see if it could engergise the heat sensitive paint?

To quench you could simply try a ducted fan to blow and cool down the heated area.

Cheers
Keith


i'll look if i do have IR laser diodes laying around ,never had much luck with scrapped lasers but more than likely the reason the stuff was scrapped a dead laser ...IR diodes i would have a few of ,i will look into it ,,i know cameras can pick up the IR light so least you know what ever your testing works in the first place .

I will have a look if uv has any effect ?

Yes the fan is a good idea !

This test worked better than i expected on this wood ruler i was not expecting a clean lines with the fading i am pretty sure a screen of this stuff could out do the glow paint i would think ..... it would be interesting to know how many SSTV and fax lines it could display .

Yep its worth looking into to for sure ,the step of seeing how hard it is charge up ..i am sure some paints are more sensitive than others glow paints a bit like that too.
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Re: Heat sensitive paint

Postby Harry Dalek » Sat Nov 18, 2017 5:26 pm

I couldn't find any IR lasers that i might of junked yet but came across one lone new IR led enough time to do a test with this .
First thoughts its a lot less sensitive to this type of led than phosphorescent paint is to uv led ......i will go looking for a laser lens to focus this light to a point but defocused as it is placing the led over the paint in one spot it does cause a slight change in the temperature and paint change's from green to yellow ....just !
Need to focus the IR led for a better result...like the old days i did with a uv leds for the glow drum sstv.
So work it will ,a guess on the laser power needed would be 500mW to 1 watt perhaps a raster does drop the laser levels a fair bit .
IR is scary lucky the camera is sensitive to IR as i see nothing looking at this led hate to think what a laser would do to your eyes in this wavelength ...
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Re: Heat sensitive paint

Postby Robonz » Sat Nov 18, 2017 5:52 pm

Hi Harry

Yes, IR lasers are very dangerous. Anyway I have been doing some research which I will share with you.

Your heat sensitive paint is called "Thermochromic Pigment" and can easily be purchased as a powder for shipping reasons. There is plenty for sale on ebay and it swithes at 31 degrees c. This means a UV or blue laser of 1/2 a watt would change the colour pretty fast in my opinion. So long as your drum does not suck the heat out too quick.

The glow stuff we have does not UV quench because it is strontium based. We need zinc sulphide based glow paint or glow powder to quench using IR.

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Re: Heat sensitive paint

Postby Harry Dalek » Sat Nov 18, 2017 8:42 pm

Robonz wrote:Hi Harry

Yes, IR lasers are very dangerous. Anyway I have been doing some research which I will share with you.


Yes its a bit worrying when you can't see it .
It's interesting side of the project i had not really looked....... into your research is welcomed !

Your heat sensitive paint is called "Thermochromic Pigment" and can easily be purchased as a powder for shipping reasons. There is plenty for sale on ebay and it swithes at 31 degrees c. This means a UV or blue laser of 1/2 a watt would change the colour pretty fast in my opinion. So long as your drum does not suck the heat out too quick.


I had the ruler in a draw and got nothing out of it at the start so 31 C sounds correct ... it was a bit warmer than that today i took it to the shed and that was a waste of time it turned yellow with the heat ,so operating range might be seasonal or indoors temperatures :wink:

I will try a uv laser on it i have one handy the led did nothing i don't have a blue one at all only red and uv..it might be a bit low for this but i will focus it to a spot and see

The glow stuff we have does not UV quench because it is strontium based. We need zinc sulphide based glow paint or glow powder to quench using IR.

[/quote]

I will try the original glow paint that might be the other type and i have glow powder that's different as well i only tried it on the new paint ..it was interesting giving the reverse effect might mean a IR laser would light up the glow paint of this type .
Good information Keith !
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Re: Heat sensitive paint

Postby Harry Dalek » Mon Nov 20, 2017 7:30 pm

I had another go at heat sensitive paint and the IR led touch better results also tried a uv led and UV 20mw laser that did pretty much nothing ...with a higher power laser i am sure it would heat the paint but not very efficient but i suppose at least you could see if the lasers working .
Notice how long the effects last minutes not seconds

youtu.be/fBYRVoeRRuA
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: Heat sensitive paint

Postby OmegaProductions » Tue Nov 21, 2017 3:40 am

WOW! Now that's what I call impressive work! :o

That's a great idea Harry! I wonder what it could be used for displaying SSTV pictures, but anyways...I hope you enjoy doing this project Harry! :D :) :wink:
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Re: Heat sensitive paint

Postby Panrock » Tue Nov 21, 2017 4:15 am

Hi Harry,

As others have said, infra-red can be very dangerous. One brief mistake when your concentration lapses and your eyesight can be damaged for life. I prepared this safety guide for my workshop when I was experimenting with infrared broadcasting a while back. It doesn't pretend to be the last word but you might find it helpful. I used an infrared-sensitive security camera to check what was going on. You can get safety goggles from China.

http://www.radiocraft.co.uk/opto.htm#infrared_safety

Steve O
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Re: Heat sensitive paint

Postby Harry Dalek » Tue Nov 21, 2017 6:58 pm

Re: Heat sensitive paint
Unread postby OmegaProductions » Tue Nov 21, 2017 2:40 am

WOW! Now that's what I call impressive work! :o

That's a great idea Harry! I wonder what it could be used for displaying SSTV pictures, but anyways...I hope you enjoy doing this project Harry! :D :) :wink:


Only difference to my mechanical SSTV would be the a IR laser and the paint would be heat sensitive paint instead of glow paint sensitive to uv light .
I never really looked into this apart from thinking you could make a SSTV version using the idea ...The difference is no blurred image after time .......as Keith mentioned you need to cool the paint down to paint a new image with a IR laser as the image would last minutes as far as i can see .
What it should of been invented for and would of been spot on for this is noaa polar oribiting weather satellites a type of fax ..the image is very long and take a few minutes with no blurring it would of been perfect for a 1970's earth station pre PC and such (BTW theres still 2 working analog Noaas working the last we will ever have )
But i am pretty sure it could do all the longer SSTV systems only in B/w of cause and FAX which are all slow to paint the image but higher quality images.

Panrock wrote:Hi Harry,

As others have said, infra-red can be very dangerous.


Very off putting very worrying i agree ...having played with lasers as you its a device you need handle with care even the ones our eyes can detect .

One brief mistake when your concentration lapses and your eyesight can be damaged for life.


Pretty much and as we tend to use them for they will be working with rotating mirrors throwing that light at a wide arc.

My procedure is before getting one any where near a mirror is run it at lowest power so i just works then you can focus it and then try it with a mirror and can adjust the distances more safer ...once every thing looks good as far as scanning then you increase laser power...

I prepared this safety guide for my workshop when I was experimenting with infrared broadcasting a while back. It doesn't pretend to be the last word but you might find it helpful. I used an infrared-sensitive security camera to check what was going on. You can get safety goggles from China.

http://www.radiocraft.co.uk/opto.htm#in ... afetySteve O


Yes those are good tips indeed ! i bet you took care with your laser transmitter that's even harder to do safely but you managed to !
Something IR related i never really thought about but your average digital camera is IR sensitive so with IR light you have a cheap night vision camera ! makes me wonder if it could see the out line of my hot soldering iron in the dark ? and if so they must be effected by hot days heat off objects...
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: Heat sensitive paint

Postby Panrock » Tue Nov 21, 2017 7:22 pm

Harry Dalek wrote: makes me wonder if it could see the out line of my hot soldering iron in the dark ? and if so they must be effected by hot days heat off objects...


Guessing a bit here, but I would think not. The reason: at such 'low' temperatures the bulk of the infra-red emissions lie in the longer wavelengths or far infra-red. Your average camera is only sensitive to near infra-red.

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Re: Heat sensitive paint

Postby Harry Dalek » Tue Nov 21, 2017 8:26 pm

Panrock wrote:
Harry Dalek wrote: makes me wonder if it could see the out line of my hot soldering iron in the dark ? and if so they must be effected by hot days heat off objects...


Guessing a bit here, but I would think not. The reason: at such 'low' temperatures the bulk of the infra-red emissions lie in the longer wavelengths or far infra-red. Your average camera is only sensitive to near infra-red.

Steve O


OH i didn't know that even infra Red as a band width.... well thinking too about it there are thermal cameras these must be sensitive as you say to far IR.
As far as the soldering iron idea.....say heating an iron metal to higher temps idea there must be a point between Dull heat and glowing red hot where you see it that the camera can pick it up just before that point glowing in the red spectrum getting my head around it i am forgetting IR bandwidth must really be the same as a temperature range as the other light wavelength colour comes with higher temperature's...temperature increase frequency increase yes ...
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: Heat sensitive paint

Postby Panrock » Wed Nov 22, 2017 6:39 am

You've got it Harry. Here's a selection of black body spectra-with-temperature I found on the internet. You can see how broad they are.

Steve O
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