Digital BW, The Print

>>>... So, are the Archival K and UC Photo Black the same stuff?
>>>Epson told me the UC photo black had a higher dmax ...

Ernst wrote:

>Not without speculation but:

>Reading the MSDS sheets of both inks there are some differences:

Yes, I've been looking at the MSDS sheets, and I'm beginning to wonder if
they are written in a way that is intended to confuse.  For example, the
7500 yellow states, "Proprietary dyes and pigments ... <5-10%."  For the
10000 yellow, however, it is "<5%."  The other Archival colors have "<3%."

If one says "less than 5 to 10%," what does that mean?  Does the range mean
that their quality control is so bad that any one batch may have twice the
pigment load of others?  I doubt it.

It could mean that, "Our ink has less than 3% pigment, but we're not about
to tell our competitors or others just what we're doing."  After all, if the
ink has, say, 2% pigments, then saying "less than 10%" is true, even if a
bit misleading.

So, I think there may be some distinct limits on what we can draw from these
sheets.  On the other hand, they do appear to have some interesting
information.

>...Archival black and ... Ultrachrome Photo Black. Both have more than
>3% Carbon black but Photo Black has more than 5% proprietary
> black/pigment as well. Archival Black just more than 1%.

Are these "hybrid" pigment/dye inks?

When they mix "Proprietary dyes and pigments" it may be telling us little.
For example, if they have a proprietary pigment, it could be better than
carbon.  After all, we know all too well that carbon does oxidize.  Maybe
they've found a black (or very dark brown for the Matte Black) pigment that
oxidizes more slowly.  (Maybe this is their contribution to lessening global
warming!)

I've thought that the Archival K, for example, must have something other
than carbon in it, because it is relatively neutral.  I thought that carbon
was more brown.  I assumed that Epson had found a way to get a neutral
coating on the carbon pigment before it was coated.  As such, there would be
no disolve dye in the mix, and that disolved dye is the real problem.

So,what I'd like to know is whether there is any dye in solution.  I'm
afraid only the fade tests will really tell.  I haven't even been able to
see in paper chromatography test the dye in most of the third-party black
pigs, which seem to have them in there to some degree.

But, the bottom line is that the UltraChrome blacks do seem to have a lot
more "proprietary dyes and pigments" in them.  I doubt they'd want to
exaggerate this number, because it suggests fading.

In the color MSDS sheets, the UC inks also seem to have a much higher load
to pigs -- 7% v. 3% for Archival.  This higher loading of pigment is
consistent with what I've heard elsewhere.

So, if UC Photo K is not the same as Archival K, why isn't it much darker?

(By the way, I can get the 7500 Archival K dmax up to 1.54 by double
printing.  It looks better/blacker than the FS-K on this new EEM due to the
cooler black tone.  The reverse paper feed allows a double print with a
registration within about 0.5 mm.  So, a "select by color range," reduce
selection size slightly,  and feather edges allows a black load that is
limited by the paper's ability to hold the amount of pigment.  With coating,
even that will be increased, since the coating allows a heavier ink load.
This reverse feed capability could be very interesting for some images --
but it could also just be a waste of time.  The 7500 puts down a 1.50 black
after the dry-down in standard, single printing.)

>... the Grey Ultrachrome MSDS you will see stranger
>percentages. The carbon black is <1% but there's <8% proprietary
>dye/pigment in the mix.

Very interesting.  I think there is a chance that a higher load of a lighter
pigment would be more lightfast.  I need to test this stuff against the
diluted Arc K.

> The Matte Black has a proprietary dye/pigment as the
>only colorant at <7%, no carbon black mentioned.

Again, very interesting.  My PhD (carbon related thesis and career)
brother's initial opinion of the carbon pigment ink was that carbon might
not be the best substance for our uses.  Maybe Epson has found that same
thing.  Such a shame, I liked the "carbon print" label so much more than
"proprietary dyes and pigments" print.

>For the Grey you don't need any extra black to get density
>so there must have been another reason.

Yes, and lightfastness, metamerism, cost, settling (7500 instructions warn
to shake the cartridge before installation and that 6 months may be the life
of the cart once opened), avoidance of carcinogenic substances in the
manufacturing facility, ... could all be reasons.

>Next to the Archival Yellow I still think that the
>transparent encapsulation on the pigment particles played a
>role in metamerism of the Archival inks.

I was suspicious of that also.  However, the pure Arc-K quads and "Black ink
only" 2000P, etc., prints don't seem to have any significant metamerism.

Paul
http://www.PaulRoark.com