Gloss optimizer and fading of dye inks

[Ink stained Fingers]

16 weeks have passed, and the pigment inks are fading slowly - very slowly, currently outside in a
pretty cold and moist environment, so it's mostly a gaseous agent - ozone - causing the effect, barely any UV radiation. A gloss/chroma optimizer overprint - complete - does indeed has a
significant effect - I'm listing here the luminance changes vs. a ref print kept in the dark and pretty much shielded off.

Epson compatible pigment ink with and w/o GO

with GO____after 8 weeks______12 weeks __16 weeks

C___________________1____________1________1
M___________________0____________0________0
Y___________________0____________0________0
K___________________0____________1________2

Sum_________________1____________2________3

w/o GO

C___________________1____________3________4
M___________________2____________2________6
Y___________________1____________2________3
K___________________1____________1________2

Sum_________________5____________8_______15

 

[jtoolman]

Well, the inkjet printer prints by placing dots on the paper surface. No matter how you apply GO short of a roller or spray it will leave uncovered surface area. It matters not what color was chosen. If you need a better coverage ratio, you might want to make multiple passes with a GO cover image each with an offset but again there is no guarantee of complete coverage. Remember inkjet = intermittent dots. Not a continuous spray. Dots are "close" but not complete.

GO optimizer was meant to fill in areas where there is no ink as opposed to covering the whole print, which as described above is still not possible if it was applied with an inkjet printer.

So keep these points in mind when experimenting with GO.

If you apply GO with a spare printer like an old EPSON 1400 and use QuadTone RIP using a custom curve I can apply a coat of GO that looks completely wet or one that is barely noticeable. The Custom Application QTR Curves control the amount.
Joe

 

[Ink stained Fingers]

I did a quick test of the ink coverage on the paper, with black ink instead of GO, black ink in the black channel, with matte paper quality strong, and I get this under the microscope


and I turned up the gamma pretty much to separate the actual black dots and the dot gain/ink spread around it, and there are some sparse small white spots with no ink coverage at all, looking to the histogram I get a number that these light areas don't cover more than 0.5% of the image.
A 2nd overprint would cover those but I wouldn't expect too much additional gain from it, the paper surface is essentially covered with a GO layer already.

 

[Ink stained Fingers]

The pigment inks with a GO overprint are doing better than without GO with their fading performance, that's the numbers now after 18 weeks

Epson compatible pigment ink with and w/o GO

with GO____after 8 weeks______12 weeks __16 weeks__18 weeks

C___________________1____________1________1___________2
M___________________0____________0________0___________0
Y___________________0____________0________0___________0
K___________________0____________1________2___________1

Sum_________________1____________2________3___________3

w/o GO

C___________________1____________3________4___________5
M___________________2____________2________6___________5
Y___________________1____________2________3___________9
K___________________1____________1________2___________2

Sum_________________5____________8_______15__________21

The deltas are increasing, the yellow now seems to become the weakest ink , similar
to Aardenburg's findings about weak yellow pigment inks across the range of tested inks.
Epson calls it 'Gloss Optimizer' and Canon 'Chroma Optimizer', both effects of this 'ink' are visible and measurable. But no company is referring to an additional benefit of a better fading performance as well.

 

[Ink stained Fingers]

Based on @jtoolman 's comments above I tested the GO overprint, I checked the 'ink' - GO coverage on the paper which appears to be pretty complete by printing via the black ink channel. And I'm testing the fading protection one or two layers of GO may give and whether that would make a difference.

That's the test patches
left - w/o GO overprint
middle - with 1x GO
right - 2x GO, the 2nd layer printed some hours after the first one

Apparent are reflection differences , there are no visible changes in colors when viewed directly , and the gamut between these print does not change, the spectro is operating with a viewing angle of 0 deg. The changes appear when turning the print against reflecting light, the print with 1x GO looks like viewed through a glass screen, and the print with 2x GO looks almost like the one w/o GO at all , the 2nd overprint takes that glassy look away again. Please consider all this experimental at this time, it might be interesting to do some more testing but I'm not recommending it at this time for general use.

And how about the fading - the black patch of the left section happily turned brown after 2 weeks - it's the L300 ink - and there is no change yet measurable under the 1x or 2x GO overprints , the GO overprint(s) do a pretty good fade protection against
the current pre-winterly weather conditions

 

[Ink stained Fingers]

it's typically pretty difficult to make a forecast for the year starting today, but I just expect with rather high confidence that dye inks continue fading - everything else would be a pretty big surprise.....
So I looked again to the patches now after 4 weeks with and w/o GO overprint - black starts turning into a chocolate brown unprotected - the protected patches don't show a relevant shift yet - regardless of 1x or 2x overprint, so it needs some more ozone whatever to show possible differences.
The visible differences of the gloss appearance remain for the 1x and 2x patches

 

[Ink stained Fingers]

It's the same situation after 6 weeks - the patches w/o GO overprint are fading along - as expected, the patches with 1x or 2x GO don't show signs of fading yet.
I had a look to some other aspects of the GO application, as mentioned before, it makes visually perceptible differences - and these are different with 1x or 2x overprints.
Epson and Canon are advertising this clear ink as a gloss or chroma optimizer in context with pigment ink prints. There is another effect that the GO overprint can improve the fading of dye ink prints very much, and the GO has impact onto the overall gamut of a print.
That's the gamut at L=50 of a typical pigment ink print

with the red line - no GO _ green line 1x GO _ blue line 2x GO, the GO overprint increases the gamut somewhat
This is the situation at L=15 , at the darker colors

The gamut gets wider with a GO overprint - 1x or 2x, and there is another benefit that the
black level drops to
no GO - L=12 1x GO - L=10, 2x GO - L=8 wo that's quite some gains, the improved black level and wider gamut for darker colors becomes visible test prints in direct comparison. And there is a visual difference as well - 1xGO takes away the bronzing of pigment inks, improves the blacks and balances gloss differences between areas with different ink densities to a degree. 1xGO in unprinted areas e.g. edges around the print or or white areas in the print changes the look of the paper white. Prints with 2xGO overall look slightly better to those with 1xGO, the glassy look of the paper white is gone, there is not much further visible difference between 1xGO and 2xGO prints, the differences in gamut are only visible in direct comparison.
How does that all look with dye prints with 1x or 2x GO:

red - no GO _ green 1x GO _ blue 2 x GO, the gamuts with GO at L=50 are slightly smaller than w/o GO, opposite to pigment ink prints

The GO is narrowing the gamuts at darker colors, and is affecting the black levels as well
no GO - 5 _ 1 x GO - 7 _ 2 x GO - 8 - the black level is weakening, effects all opposite to those above with pigment inks.
And how does it look - the 1xGO is changing the look of the paper white (glossy) , and prints look as if they are behind glass, color changes are not visible, this glassy look is gone with 2x GO , such prints look somehow better than those with 1xGO (just my personal preference). The GO benefit on dye inks is not so much in the gloss appearance, bronzing etc, the only benefit would be a significant protection against ozone of weaker dye ink prints as shown in the other thread.

 

[Ink stained Fingers]

It's now 24 weeks that I keep a patch outside for a fading test - with Epson compatible pigment inks and with a G/ overprint

Epson compatible pigment ink with and w/o GO

with GO____after 8 weeks______12 weeks __16 weeks__18 weeks___24 weeks

C___________________1____________1________1___________2_________2
M___________________0____________0________0___________0_________0
Y___________________0____________0________0___________0_________0
K___________________0____________1________2___________1_________2

Sum_________________1____________2________3___________3_________4

w/o GO

C___________________1____________3________4___________5_________6
M___________________2____________2________6___________5_________5
Y___________________1____________2________3___________9________10
K___________________1____________1________2___________2_________3

Sum_________________5____________8_______15__________21________24

It is apparent that the gloss optimizer overprint provides a significant fading
protection, as well for pigment inks, protection against the typical ozone etc
gaseous agents, there is not much sun/UV radiation outside . And these numbers
show the same effect as reported in various tests by Aardenburg that yellow pigments
are pretty weak overall. Epson had promised to have that fixed and improved with
the latest Ultrachrome pigment inks for the P600/800 and alike printers.
It is unkown at this time whether newer 3rd party inks compatible with these printers,
by farbenwerk, Lyson, PC, Vermont Ink or else provide this improvement of the yellow pigment inks as well.

The trend and positive effect of a GO overprint is clearly visible, I'm closing this test
now after 24 weeks.

 

[Flying Scotsman]

I would like to thank you once again for all the time and work you put into these tests. They are invaluable for us who are refilling and wanting the best possible quality.

Thanks again and keep up the good work

 

[Ink stained Fingers]

Differences - specifically in the performance of yellow pigment inks - between the previous and the current version
of Ultrachrome HD pigment inks are presented here by Aardenburg:

http://www.aardenburg-imaging.com/optical-brighteners-obas/
I have so far not seen any comments in this respect by 3rd party ink suppliers whether their Ultrachrome HD compatible inks offer a similar improvement of the yellow pigment inks. Several of those have already advertised that they did improve or exceed the black level of their inks vs. the Epson HD inks.