Digital BW, The Print

While this explanation is one way of comparing dyes and pigments, many
of the analogies are not very accurate.

In both dye and pigments ink formulations the struggle is to keep the
components in solution. Fortunately for printing on paper type
substrates, requires much less dye concentration than that of
pigments. This is one reason that dyes don't tend to settle like
pigments do. They both use co-solvents to try and keep them in
suspension. In pigments, the formulations with encapsulation and other
co-solvents used, and the much greater pigment load lead to problems
of "build-up" in printer parking stations and wiper blades.

As for the greater "water resistance" of pigments, this is due more to
the microporous ink receptor for pigmented printing materials. Also
the the acrylic encapsulations used in some pigmented inks.

As for the greater fade resistance of pigments, this is due several
reasons. First, dyes are very sensitive to UV fade, which pigments are
fairly resistant to.(this has to do with the chemistry of dye molecules)

Not all pigments are more resistant to light fade than some dyes. Dyes
tend to suffer from what Wilhelm calls "catalytic failure". This
happens when dyes intermingle on the print surface. This is why
swellable polymer ink receptors tend to give dye prints a much longer
life. But high humidity conditions also tend to contribute to shorter
print life of dyes even with swellable polymers.

Dyes are more transparent than pigments, although the newer generation
of pigments which are chemically created are much more transparent
than traditional pigments. The transparent nature of dyes leads to a
greater color gamut and "luminosity", that many photographers value in
their prints.

John Nollendorfs  

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, Andrew Sharpe
<asharpe@...> wrote:
>
> Hi folks,
> 
> Even though the level of expertise of the contributors to this list is
> very high, there may be others who, like myself, are just getting
> started. I recently received an explanation of pigment vs. dye from a
> company that sells ink, including WJ1082 (aka Eboni K). The explanation
> helped me to understand more clearly; perhaps it will help others. I
> asked him for his permission to post it here. I have no affiliation with
> Mr. Lewis, except as a potential customer.
> 
> Andrew
> 
> 
> BEGIN QUOTE
> 
> The dye in the dye-based ink dissolves in water like sugar does
> in water -- completely.  Pigment does not dissolve completely. It
> is more like a flour and water mixture.  Because of this,
> dye-based inks flow better and have been the standard in inkjet
> printers. But the dye will re-dissolve and the ink will flow
> across the paper if drops of water hit the paper.
> 
> Pigmented ink particles tend to settle into the tiny fibers that
> make up the paper.  As the ink dries, the pigment particles get
> stuck in the fibers. Thus, the pigmented inks are more water
> resistant than the dye-based inks. Only about 5 to 10 percent of
> the ink will re-flow if the paper is hit by water.
> 
> The molecules in dye-based inks are spread out. You might think
> of dye-based ink on paper as similar to a beach covered with
> sand. Because of this, dye-based ink tends to fade quicker, since
> all of the molecules are exposed to the chemical and
> sunlight-caused reactions that fade the ink. You may notice
> fading of dye-based inks exposed to direct sunlight commonly in 6
> to 12 months.
> 
> Pigment particles are similar to large pebbles on a beach. It is
> much more difficult for sunlight and chemicals to react with all
> of the pigment molecules, since most of them are hidden inside
> the "pebbles". Pigmented inks will usually last for many years
> before fading becomes noticeable.
> 
> It is possible to get more "color" into pigments than into dyes.
> Therefore, pigmented colors tend to be more vibrant than
> dye-based colors. And pigmented black inks tend to be slightly
> darker than dye-based inks.
> 
> Sincerely, Gordon Lewis
> The Printer Filling Station
> www.PrinterFillingStation.com
> 1403 Shiloh Oak Drive
> Loganville, Georgia 30052
> Office 1-800-404-4923
> 
> END QUOTE
>