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Author Topic: New Inks in 9800 resulted in Color Shift  (Read 219 times)

Doug Gray

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New Inks in 9800 resulted in Color Shift
« on: January 28, 2019, 11:22:33 AM »

NOTE: Epson hasn't changed anything.  Turned out the problem described here was from ink sets purchased on EBay that claimed to be genuine Epson inks and may well have been. However one ink, Cyan, had an expiry date of 2012 while the others were 2019. I had not noticed the anomaly until buying new inks directly from Epson and noticed changes. The following shows a rather circuitous route to discovering this cause. I should have started looking at the dates of both the new inks and old ones.

None the less, this may be useful for someone that has older inks and wonders what the effect might be.

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Bought new Epson Inks (From Epson, as usual) ran a dE check on a standard chart. Just before I did that I printed the same target with the older inks.

Average dE 1976: 6.7
Average dE 2000: 3.7

As bad as that is, reference prints (with the older profile) looked OK but, side by side with older prints, there are subtle differences. Neutrals had no visible shift.

Looking at the ICC profiles from each the new ink sets have a lower black point and generally slightly larger gamut below L*=50, Above that the green's are a bit smaller while the orange/yellows are a bit larger. Patch tool reports gamut volume increased from 833k to 840k for what that's worth.

I check charts every time I put new ink in as well as from time to time during ink usage. I have never seen such a large shift with new inks. Previously, the biggest shift was about dE2000 of 1.1 average and that was from a fairly old inks.

Perhaps there has been a formula change?
« Last Edit: January 29, 2019, 10:58:11 AM by Doug Gray »
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Doug Gray

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Re: New Inks in 9800 resulted in Color Shift
« Reply #1 on: January 29, 2019, 12:43:03 AM »

Looks like a probable formula change. Printer's fine.

I was quite concerned because the changes were so large. Did something suddenly happen to the printer?

So I investigated the gamuts of profiles made with before/after ink change. There was little difference at higher luminosities but at lower L*s the saturation on the +b* (with the a* held at 0) was higher with the new inks while with the -a* (with b* held at 0) the old inks had higher saturation. Other parts of the gamut were close, ie: orange, red, magenta and blue.

This led me to speculate the Cyan spectra differed and the new inks were cutting off earlier than the old one.

Next I compared the spectra for RGB (0,255,255) which produces pretty much pure Cyan.

The new ink exhibited both a lower peak amplitude but, more importantly a 3nm shift, with the peaks normalized, to shorter wavelengths along the region from 500nm to 540nm. This may not seem like much but it happens to be in one of the most sensitive areas of the visual response near the peak of the horseshoe CIEXY.

1. It accounts for the differences after I changed ink.
2. It's not possible for any change in the printer/driver/paper selection, etc. to produce this shift. It's a property of the Cyan (not Light Cyan) ink. The ink is dated 20180627 (manuf. I assume) and Exp 2010627

The largest dE 1976 occurred at Lab(20,-53, 8 ) v (16,-39, 5) which is about 15

Fortunately, this area is not very visually sensitive and the dE00 is much lower. But still!


Looks like I need to re-profile all the papers I use. No idea if it's just a bad batch but it is highly annoying.
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samueljohnchia

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Re: New Inks in 9800 resulted in Color Shift
« Reply #2 on: January 29, 2019, 03:08:27 AM »

Could it be pigment settling that caused this?
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Doug Gray

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Re: New Inks in 9800 resulted in Color Shift
« Reply #3 on: January 29, 2019, 03:18:24 AM »

Tracked it down to old ink.

Turns out I had a batch of inks, all of the ones I replaced expired in 11/2019. Except one, Cyan, which expired in 2012. I had bought batches of Epson ink sets from Ebay. I checked the dates but not on each cartridge. I had a long period, over 5 years, where I didn't use the 9800 at all but it was revived and has worked quite well since. And I made new profiles for it with the I1 Pro 2 then later the i1iSis. Until I got the new ink directly from Epson the results, post revival, matched quite closely when I'd change ink.

So I was curious what the printer had done before its long period of non use.

I ran the most extreme RGB values to get the Lab (AtoB1 tables) from sets of profiles I made at different times all the way back to 2007. All the older ones are pretty close to what the new inks show but the ones made after bringing the 9800 back to life all show the same characteristics of the bad Cyan so I probably somehow just bought old Cyans. No idea how 2012 date could have been mixed in with 2019 on all the others. I don't have prior Cyan cartridges to check dates on but all the profiles I made since restoring the 9800 and buying Epson ink (supposedly genuine from Ebay) show the same color shift.

From now on I'm only buying direct from Epson.
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