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Author Topic: appearing ink?  (Read 8987 times)

Offline eemil

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appearing ink?
« on: 16/10/2007 14:04:10 »
hello everyone.
Im artist from Finland and trying to find a way to create appearing ink. the idea would be it to appear after a while its being used. Was thinking if anyone has any ideas.. Maybe those could be some uv-sensitive liquids or just with air, and i mean oxygen.


 

another_someone

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appearing ink?
« Reply #1 on: 16/10/2007 14:11:39 »
I don't have an answer, but I am wondering how you intend to apply the ink without being able to see it - or are not not concerned about any precision in the way the final image shows up after the ink becomes visible?
 

Offline eric l

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appearing ink?
« Reply #2 on: 16/10/2007 16:36:53 »
One could imagine some ink based on copper sulphate as colour agent.  In the anhydrous form it is near colourless, in the pentahydrate form it is deep blue.

An ink like that would be visible while write, disappear when paper and ink are fully dry and reappear with increasing relative humidity.

It may be possible that you would have to superdry (e.g. in a microwave) to make the writing disappear.

A "real" ink of course contains not only the liquid phase and a colour agent, but also a binder (although much less than e.g. a paint).
 

Offline Bored chemist

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appearing ink?
« Reply #3 on: 16/10/2007 20:08:09 »
Dilute copper sulphate solution makes a good invisible ink. If you heat things written with it it catalyses the charring of the paper and the "writing" turns black.
I don't think you could easilly get the stuff dehydrated by heating it because it would char. You might manage with a dessicator.


"don't have an answer, but I am wondering how you intend to apply the ink without being able to see it "
You could load it into a printer.
 

Offline eric l

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appearing ink?
« Reply #4 on: 17/10/2007 08:07:54 »
Dilute copper sulphate solution makes a good invisible ink. If you heat things written with it it catalyses the charring of the paper and the "writing" turns black.
I don't think you could easilly get the stuff dehydrated by heating it because it would char. You might manage with a dessicator.


"don't have an answer, but I am wondering how you intend to apply the ink without being able to see it "
You could load it into a printer.

1. If you char the paper, the image will remain visible after that.  I thought we were looking for something reversible.
2. I was not thinking of heating for  dehydrating the copper sulphate, but of microwave drying.  Microwave drying is (occasionally) used for drying out the wet streaks in paper :  the energy is absorbed exclusively (or almost)by the wet streaks, not by the dry paper around.  I do not know however if microwave treatment would be enough for dehydrating the pentahydrate to the anhydrous form. 
 

Offline DrDick

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appearing ink?
« Reply #5 on: 17/10/2007 16:17:04 »
Aqueous silver nitrate would be really good (although maybe expensive?) for this application.  Silver nitrate is a white solid, and forms a colorless solution, but is a good oxidizing agent.  When exposed to an oxidizible material (paper, skin, etc.) the silver is reduced to metallic silver particles, which will appear brown-black. 

This actually happens quite often when working with silver nitrate solutions.  If you get it on your skin, you will get brown spots that appear within a few hours.  If you have some in a bottle with a paper label, then spill or drip some on the label, the label will turn brown or black where the silver nitrate comes in contact with the label.

Dick
 

Offline eemil

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appearing ink?
« Reply #6 on: 17/10/2007 18:50:40 »
Hello again..
First of all .. thanks for the good ideas.. i think i need to explain my project closer..so you would get the idea what im working with at the moment. in the museum my idea was to pour this "some2 liquid to the cleaning womens normal liquids and in this way.. after a while show to the people their way of cleaning.. and dont worry.. this is not any anarchy thing.. i have permissions..hehe.. well i think the silver nitrate would be the best thing at the moment.. it sounds like these photo emulsions.. the only thing is that they tend to have a bit of a strong smell.. and i dont want the quests to be forced to that.. and maybe it is toxic too?.. this forum really seems nice though.. thanks for sharing...

eemil
 

Offline Bored chemist

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appearing ink?
« Reply #7 on: 17/10/2007 19:18:22 »
". If you char the paper, the image will remain visible after that.  I thought we were looking for something reversible."
And my point was that this irreversible balckening might happen before you got the stuff anhydrous.

If you want to check that the cleaner mops everywhere, then a fluorescent tracer dye would be an easier way to do it.
 

Offline RD

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appearing ink?
« Reply #8 on: 19/10/2007 17:16:43 »
Pigments are available which change colour when exposed to heat or UV light.

Photochromic pigment (UV): http://www.mutr.co.uk/catalog/product_info.php?products_id=571

Thermochromic pigment (heat): http://www.mutr.co.uk/catalog/index.php?cPath=79

(And no, I'm not an agent for MUTR  :))
« Last Edit: 19/10/2007 17:19:49 by RD »
 

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appearing ink?
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