RE: A question about inks

[Gawain Weaver <gawain.weaver@gmail.com>]

The distinction here is probably similar to that between today's inkjet inks
and pigment inks. Inks are much smaller, often individual dye molecules or
very small aggregates of dye molecules (~3-20nm in size)  that are soluble
in their medium, while pigments inks are larger aggregates (~100-1000nm or
larger) of the same colorants, but due to their size are no longer soluble
and so form a dispersion rather than a solution. Pigments for inkjet would
be on the smaller side of that range, perhaps 100nm, while for offset
printing the they might be around 500nm. The individual ink molecules in
these aggregates are not by themselves any more fade resistant than before,
but there are a lot more (so it takes longer to fade), and there is a
certain added stability achieved in aggregation.

The old simplification of ink=organic and pigment=inorganic was very
convenient, but it certainly does not apply in today's world. Pigment is
really just an indication of a larger particle.

Gawain Weaver 



-----Original Message-----
From: Jack Brubaker [mailto:jack@jackbrubaker.com] 
Sent: Wednesday, December 13, 2006 12:00 PM
To: alt-photo-process-l@usask.ca
Subject: Re: A question about inks

Can anyone tell what pigment dyes are?

Jack