Digital BW, The Print

Duane,

I think you are trying to simplify the subject too much.

Carbon doesn't exist in fixed sizes of molecules, except as fullerenes 
(which are finite-sized molecules of C60, C70, etc). The usual forms of 
carbon such as diamond and graphite, are crystalline structures of 
indefinite size. So the diamond in a ring could be called a molecule!

I think people are getting too hung-up on the term 'carbon-based'. All life 
on this earth is carbon-based; the whole subject of organic chemistry is 
mainly the study of carbon-based compounds.

AFAIK, most dyes and pigments are carbon-based compounds, whether natural or 
synthetic. The difference is simply one of solubility - 'dyes' are soluble 
and 'pigments' are insoluble.

http://pffc-online.com/mag/paper_brief_chemistry_lesson/

Bob Frost.



----- Original Message ----- 
From: "dlruckus" <dlruckus@...>




Can't make a dye of anything larger than a molecule of carbon. Get 2
of them and it becomes a clump and -that-- is a pigment.

'dyes' are soluble 
> and 'pigments' are insoluble.

That's true for Epson "pigments" vs the various dyes and inks in
printers, but "pigment" simply means colorant: the stuff from which
dyes and inks are made. The word is being used inaccurately by Epson,
but perhaps it's easier than explaining "encapsulation."

Ultrachrome "pigments" are different from dyes because they are
"encapsulated" and in "suspension," not "dissolved" in a "solvent". By
contrast, dyes and inks ARE in their solvent, which is usually water.
This is said to explain Epson's arguably more archival characteristic,
and it probably explains bronzing. 

> 
> http://pffc-online.com/mag/paper_brief_chemistry_lesson/
> 
> Bob Frost.
> 
> 
> 
> ----- Original Message ----- 
> From: "dlruckus" <dlruckus@y...>
> 
> 
> 
> 
> Can't make a dye of anything larger than a molecule of carbon. Get 2
> of them and it becomes a clump and -that-- is a pigment.

Djon,

Here is another dictionary definition:-

"A distinction is usually made between a pigment, which is insoluble, and a 
dye, which is either a liquid, or is soluble. There is no well-defined 
dividing line between pigments and dyes, however, and some coloring agents 
are used as both pigments and dyes. In some cases, a pigment will be made by 
precipitating a soluble dye with a metallic salt. The resulting pigment is 
called a "lake"."

And another:-

"What is the difference between pigments and dyes?
The primary difference between these colorants is their solubility. Pigments 
used in printing inks are colorants that are insoluble in water and most 
solvents. For instance, copper phthalocyanine blue is the primary blue 
colorant used in packaging and is quite insoluble in water and organic 
solvents. As the name indicates, it is a blue pigment that includes copper. 
The rest of its structure is a highly complex aromatic structure of benzene 
rings that include nitrogen atoms.

Unlike pigments, the number of dye colorants is seemingly infinite. Dyes are 
organic colorants that are soluble, and they are commonly used in the 
textile industry and in office products, such as ink jet printers. In 
packaging applications, dyes do not have the product resistance of pigments. 
Dyes provide brilliant color and are used in products that do not require 
long-term resistance. Most have inferior solvent bleed and oxidation 
resistance."



As far as I can see, Epson is entitle to call their Ultrachrome inks 
pigment, just as many other ink firms sell 'pigment inks' as well as 'dye' 
inks (MIS, Lyson, etc).

According to Epson, the encapsulation of their pigments in a coating of a 
resin polymer is designed to prevent the pigments aggregating and settling 
out of suspension. If the polymer were to have hydrophilic groups on its 
surface (I don't know that it does), it could even be effectively 
'solubilising' the pigments.

Bob Frost.

----- Original Message ----- 
From: "Djon" <westsidemaurice@...>

 'dyes' are soluble
> and 'pigments' are insoluble.

That's true for Epson "pigments" vs the various dyes and inks in
printers, but "pigment" simply means colorant: the stuff from which
dyes and inks are made. The word is being used inaccurately by Epson,
but perhaps it's easier than explaining "encapsulation."

Ultrachrome "pigments" are different from dyes because they are
"encapsulated" and in "suspension," not "dissolved" in a "solvent". By
contrast, dyes and inks ARE in their solvent, which is usually water.
This is said to explain Epson's arguably more archival characteristic,
and it probably explains bronzing.

> Ultrachrome "pigments" are different from dyes because they are
> "encapsulated" and in "suspension," not "dissolved" in a "solvent". By
> contrast, dyes and inks ARE in their solvent, which is usually water.
> This is said to explain Epson's arguably more archival characteristic,
> and it probably explains bronzing.
------------------ 
Sure a pigment is only as good as the quality of its components.
Forgeting Epson and encapsulation for  a minute, MIS, Media Street, and 
Lyson "pigments" out perform dyes also in their stability, but also show 
"bronzing" on rc media. The many fine monochrome pigments like MIS and 
Piezzotone also show some bronzing if I am not mistaken, thought Paul 
seems to have done something to reduce this with his inkset.

Then there are the other colors for art mediums other than photography. It has 
always been my assumption that fine watercolors and oils like Windsor 
Newton have higher quality and more pure "pigments" than some of the 
cheaper brands that combine pigments and dyes for greater intensity as well 
as lower prices, such as Sekura. Someone once asked Wilhelm at one of 
those seminars that I attended that "well aren't Iris prints using their original 
inkset just as pernanent as waterolors, and thus should qualify as permanent 
art prints? He said there are as many kinds of watercolor and oil mediums as 
there are inks for photography and they range from the extremely stable 
pigments of Windsor Newton, to very unstable products ,so you can't group 
them all together as one thing. I have also heard that offset lithography shops 
used to use inks that had a high pigment content and were much more 
permanent in the past than these inks are now, which use  more unstable 
dyes primarily as a colorant - and that this is an issue with offset limited 
edition prints of paintings, etc..

John

I don't think Epson is misleading at all.  They use dye and pigment in their
purest sense.  The fact that the terms overlap at some point is moot when
dealing with the general public.

All they (any printer manuf.) want is to sell the machine to the home shmo
for about $100, give him a cartridge he can't fully empty and make a high
profit on the refill.  

I am sure Epson understands two things:
  1. Professionals using the machines know the differences in the inks and
will do their own research, etc.

  2.  Groups like this will take care of what's left <BGGG>!   Ad nauseum if
necessary.

Seth 

==-----Original Message-----
==From: Djon [mailto:westsidemaurice@...] 
==
==
==
== 'dyes' are soluble 
==> and 'pigments' are insoluble.
==
==That's true for Epson "pigments" vs the various dyes and inks 
==in printers, but "pigment" simply means colorant: the stuff 
==from which dyes and inks are made. The word is being used 
==inaccurately by Epson, but perhaps it's easier than 
==explaining "encapsulation."

Bob-

Now you have me wondering.  

Her is a polymer resin.  Why not add an UV inhibitor and make it really
work?

Also (and separately), WHY is this polymer, once hardened, so susceptible to
the air?  Seems like the problem is in the mix.

Seth


==-----Original Message-----
==From: Bob Frost [mailto:bob@...] 
==
==According to Epson, the encapsulation of their pigments in a 
==coating of a resin polymer is designed to prevent the 
==pigments aggregating and settling out of suspension. If the 
==polymer were to have hydrophilic groups on its surface (I 
==don't know that it does), it could even be effectively 
=='solubilising' the pigments.
==

I agree. It's no different than house or car paints.  

Quality is quality, although it can had for less than top dollar.

Seth

==-----Original Message-----
==From: john dean [mailto:deanwork2003@...] 
==------------------
==Sure a pigment is only as good as the quality of its components.
==Forgeting Epson and encapsulation for  a minute, MIS, Media 
==Street, and Lyson "pigments" out perform dyes also in their 
==stability, but also show "bronzing" on rc media. The many 
==fine monochrome pigments like MIS and Piezzotone also show 
==some bronzing if I am not mistaken, thought Paul seems to 
==have done something to reduce this with his inkset.
==
==Then there are the other colors for art mediums other than 
==photography. It has always been my assumption that fine 
==watercolors and oils like Windsor Newton have higher quality 
==and more pure "pigments" than some of the cheaper brands that 
=