Digital BW, The Print

Should we not avoid using the term 'Pure Carbon' for pigment inks, since it 
isn't. The first line in Paul's article is clearer - calling them '100% 
carbon pigment (no color inks)'. The qualification is important in making it 
clear what is 100% (not the carbon, but the pigment). A hyphen between 
carbon and pigment would be even better IMO.

You wouldn't want to mislead your customers, would you?

Bob Frost.

----- Original Message ----- 
From: "chriskjezp" <chriskresser@...>
To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
Sent: Wednesday, August 29, 2007 9:47 PM
Subject: [Digital BW] Re: R1800 "pure carbon" approach?


I have since found and read Paul Roark's excellent article describing
the "pure carbon" approach in full detail.

Hi Bob,

>Should we not avoid using the term 'Pure Carbon' for pigment inks, 
>since it isn't. The first line in Paul's article is clearer - 
>calling them '100% carbon pigment (no color inks)'. 
>The qualification is important in making it 
>clear what is 100% (not the carbon, but the pigment). 
>A hyphen between carbon and pigment would be even better IMO.

The truth is that we consumers will probably never get access to the entire
chemical makeup of our materials.  This --
http://www.paulroark.com/BW-Info/Pigment-dispersion.jpg  -- is my best guess
as to the dispersion approach used on the carbon pigments that are sold by
MIS.  Between what MIS was able to find out from its supplier and my hacking
their web pages, I came up with this as the most probable edge treatment.
(Epson calls the edge treatment of its MK a "solubility" treatment -- which
makes no sense for a pigment.)

I think the hyphenated carbon-pigment may be a good solution, in part
because it also makes clear there are no dyes in the image-forming substance
(as far as we know and can tell from fade tests).

It turns out some of the US government's consumer protection laws and rules
allow the use of statements that imply if not state "pure" or "100%"
whatever when the "impurities" are added to the product to improve it.
Down, wines, and no doubt other products are in this category.  It may be
that the edge effects are in this category.  They may not be image-forming
at all.  For all I know they may evaporate.  On the other hand, there are
also binders that do stay with the pigment, although not necessarily image
affecting.

How much one has to disclose to make the material differences clear to
consumers might not be clear itself.

Paul
www.PaulRoark.com

Paul,

Thanks for your reply.

> http://www.paulroark.com/BW-Info/Pigment-dispersion.jpg

That diagram looks just like the Cab-O-Jet 300 black pigment as described in

http://nanoparticles.org/pdf/Kowalski.pdf  !   ;)


I found the introductory bit of the following article interesting (about 
manufacture and properties of carbon blacks) - 
http://carbon-black.org/carbonblackuserguide.pdf, especially the bit about 
size and aggregates and conglomerates.

> (Epson calls the edge treatment of its MK a "solubility" treatment --  
> which
> makes no sense for a pigment.)

Well, the borderline between 'soluble' and 'insoluble' is a bit gray, isn't 
it? Adding hydrophilic groups of various sorts makes the carbon black 
particles 'self-dispersing' in aqueous solution, by enabling hydrogen 
bonding with the water. So for most people, making the particles 'more 
soluble' is probably OK if not technically accurate.

I still haven't understood why smaller particles of carbon black are 
apparently blacker than larger particles. Good for us that they are, but I'd 
like to understand why.

Bob Frost.



----- Original Message ----- 
From: "Paul Roark" <paul.roark@...>

Hi Bob,



>> http://www.paulroark.com/BW-Info/Pigment-dispersion.jpg

>That diagram looks just like the Cab-O-Jet 300 black pigment
>as described in

>http://nanoparticles.org/pdf/Kowalski.pdf ! ;)

Ah, more by him.  It was not from that PDF, but a related one I managed to
find on the Cabot website -- subsequently removed.

...

>I still haven't understood why smaller particles of carbon 
>black are apparently blacker than larger particles. 

I'm not sure either.  The smaller color pigs also are said to have higher
gamut -- maybe a related issue.  Dyes make the finest, more even coating,
and they have yet higher gamut usually.

Paul
www.PaulRoark.com