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Erasable Ink

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All pigments (with the possible exception of things like carbon black) can be faded by strong light, particularly UV.

In general, the pigment industry has striven to minimize this effect, producing pigments which are as stable as possible and do not easily photobleach.

Howevertheless, it should be possible to produce pigments which are particularly prone to photobleaching.

If so, there is the option to produce a range of printer inks which could be erased by brief exposure to a strong UV light.

This would enable documents to be erased, and the paper recycled.

MaxwellBuchanan, Jun 23 2014

Paper Rewritable
[xaviergisz, Jun 23 2014]

blue wool scale http://en.m.wikiped...iki/Blue_Wool_Scale
[mylodon, Jun 23 2014]

Latent_20etiolation_20messages The perfect inks for this [hippo, Jun 24 2014]

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       // All pigments (with the possible exception of things like carbon black) can be faded by strong light, particularly UV //   

       Disputed. Pigments based on metallic carbonates and oxides are extremely resistant to UV bleaching. Stained glass retains its colour despite many centuries of intentional eposure to intense sunlight. Loss of colour is usually due to leaching of the pigment by mildly acidic rainwater.
8th of 7, Jun 23 2014
  

       Living near an ozone hole has shown me that bleaching is pretty common and not related to rain anymore then gnomes crawling into your house at night, painting whiteout on your couch. I would be curious as to the implementation of this photo- eraser. Blue jeans fade quickly; why is indigo so prone.. Or is it just to acid washing?
mylodon, Jun 23 2014
  

       A number of early inkjet-printer ink formulations tended to fade with time. Just bring them back.
Vernon, Jun 23 2014
  

       //Disputed// Fair point - metallic salts (and inorganic compounds in general) tend not to bleach. However, organic pigments do.
MaxwellBuchanan, Jun 24 2014
  

       Yes, but you wrote "all". If you'd said "all organic pigmernts" we would have let it pass.
8th of 7, Jun 24 2014
  

       What happens to paper under intense UV?   

       Many printers don't deal well with simply flipping the paper over and printing the back side, since the paper is no longer perfectly flat and uniform.
MechE, Jun 24 2014
  

       //Yes, but// Yes yes, [8th]. I sometimes like to make mistakes to avoid giving the impression of infallibility, which many people find disconcerting.   

       //What happens to paper under intense UV?// Enough UV will damage it, but it would need to be a lot. I think dyes could be developed which would bleach with a fairly low UV dose.
MaxwellBuchanan, Jun 24 2014
  
      
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