Print density change after swapping out K7_7,6 & 5 for Carbon 7,6 & 5

inks
piezography

#1

Hi,
I purchased a set of Carbon inks and carts in late March/April 2012 and a few months after that I started printing with a split tone of K7N and Carbon Inks in my Epson 7800.

I had K7 Neutral in 1(K), 7(Y), 6(LK) and 5(LM) and had Carbon in shades 2,3 & 4.

The set printed well until I decided last week to switch to all Carbon inks. I replaced the K7N carts with the Carbon carts (that I filled in April 2012) that had never been used.

I did gently shake the carts before inserting them into the machine. Performed two power cleanings.

Highlight transitions (compared to a print made before the cart swap) were now very abrupt - density seemed to slightly increase before it transitioned to lighter tonality.

Eventually performed a third power clean but the highlight transitions were still off.

Replaced the Carbon shade 7 with the old K7N - shade 7. Performed a power cleaning and the highlight transitions improved significantly.

Before I return the other K7N carts to the printer I have two questions:

  • How much shaking is needed to return the old ink into suspension?
  • Is there a point at which ink is just too old to return fully into suspension?

My ultimate goal is to print Carbon inks on both matte and glossy paper (after switching to opaque shade 1 photo black ink.)

Thank you for the help!

John Parascak


#2

Hi John~

Sorry for not responding sooner, our internet was down on 7/2, and 7/3 was our last day before closing for holiday vacation, but I am answering tech support from home while we’re closed.

Piezography Neutral and Carbon inks are very close in individual shade density, so you shouldn’t see an abrupt tonal transition jump between the two ink tones. Is it possible that ink shades weren’t installed in the correct order? One power clean cycle isn’t enough to move ink from cartridge to the print head (it takes 2-3 power clean cycles to do this). I recommend you check your ink densities in carts and bottles by doing a Q-tip smear test: agitate all ink carts and bottles to ensure pigment is in suspension, then dip the end of a fresh Q-tip into an ink so the end is saturated with ink (I suggest going in order, and starting with shade 1-7), then wipe it across a piece of paper (typing paper is OK, but using a piece of print paper is best) and mark the ink smear with the ink tone and shade. Repeat with all other inks, then dry the sheet of ink smears and evaluate them to determine darkest to lightest, and figure out if the carbon shade 7 cart was accidentally mis-filled, or what happened to cause the sudden jump.

To answer your questions- if the ink is older and been sitting for a while, you should give it a good shaking by turning the bottle or cartridge upside down and right side up several times to get all the pigment back into suspension. After ink is in suspension, a regular and more-gentle agitation is all that’s needed to keep it in suspension.
Ink expiration dates are two years after the manufacture date (which is true even with Epson inks). We tell customers pigment ink should always be shaken before carts are filled/refilled, and carts should be regularly agitated to maintain in-suspension pigment for full/consistent output (plus printers should be regularly used to prevent pigment settling in the internal ink lines and dampers). Best results are obtained up to the expiration date, but if properly used/stored, inks can be safely used for about six months past the expiration date, though we after that is “use at your own risk” territory.

Please let me know what you discover after doing the Q-tip ink smear test, if you have questions, or there’s anything else I can help you with.
Best regards~ Dana :slight_smile:


#3

Dana,
Thank you for the help. No worries - I knew you were all going on vacation so I didn’t expect a quick reply - but thank you for taking the time to respond.

I put back the original 3 NK7 carts and transitions returned to normal. Thoroughly shook the 3 Carbon ink carts (waited 8 hrs) then placed them back into the 7800 but the issue remains.

[I]Is it possible that ink shades weren’t installed in the correct order?[/I]
It is possible that my brain may have slightly melted, though I thought I was keeping excellent track of things. :slight_smile:

[I]I recommend you check your ink densities in carts and bottles by doing a Q-tip smear test.[/I]
I did print the Ink Separation File in an attempt to do the same type of thing. It’s hard to tell visually but shades 5 (LM) and 6 (LK) are very close density wise but 6 (LK) is slightly lighter than 5 (LM).

I’ll test all the carts this weekend using the Q-tip method.

I own a Datacolor spectrocolorimeter (Spyder Print.) Is there any way I can measure the maximum density of each shade on the QTR Ink Separation Page to see which one is off?

Thank you again for the help.
Regards,
John


#4

Thanks for the additional information John.
Please let me know what you see after doing the Q-tip smear test (and/or scan and attach for me to see).

I have some Piezography ink measurements on Hahnemuhle Photo Rag and Epson Enhanced Matte papers, if you’d like to measure and compare, though you should be able to tell pretty easily by visually checking the Q-tip smears or printed Ink Separation test. We provide an example of a printed Ink Separation chart, which shows obvious differences in each shade: http://www.inkjetmall.com/tech/content.php?144-Print-Ink-Separation-Image-thru-QTR-Calibration-Mode

Keep me posted, thanks~ Dana :slight_smile:


#5

Ok, I’ve attached a straight scan of the Ink Separation Chart. I figured that would be the least messy way to start.

Let me know what you think.


#6

I also measured the maximum density of each step wedge.
Canson Rag Paper
K Ink 1 - 1.65
C Ink 2 - 1.51
M Ink 3 - 1.14
Y Ink 4 - 0.13
LC Ink 5 - 1.32
LM Ink 6 - 0.52
LK Ink 7 - 0.37


#7

Thanks for the additional information. After reviewing your ink densities, and comparing to measurements I’ve collected over the years, it looks like they’re in the correct range, so that’s good.
Have you printed a 21 step strip to check your output linearization? What is the exact name of the curve you’re using?

Please let me know so I can try to help you resolve this, and get back to happily printing.
Best regards~ Dana :slight_smile:


#8

The Linearization Checker shows a pretty wavy line for the inks. I printed the 21 Step Wedge on Epson Ultra Premium Presentation Matte paper. Here are the readings:
.05,.09,.13,.17,.24,.30,.36,.40,.45,.49,.55,.63,.73,.84,.93,1.02,1.12,1.23,1.35,1.46,1.53

I thought only the highlights were off but now I see the mid tones and shadows are off, too.

So, what are my options at this point? Will a custom curve fix this or do I have to toss this ink set and start from scratch?

4 of my ink carts are now fairly low. I have a feeling that dumping the four, refilling with fresh ink then having a custom curve made may be a less expensive option than starting from scratch and dumping all the inks, flushing the printer and installing a new ink set.

What do you think?


#9

Hi John~

I have plotted the measurements you provided, and attached the linearization checker below to illustrate your output.
This is showing you have a very slight lightness in your highlights and darkness in the 1/4 tones (though both are still within the “normal/linear” line), your mid-tones are a bit light, and shadows are a bit dark. I would say this isn’t horrible, but certainly isn’t perfect either, and the ups and downs will make the output look off as you are experiencing. Yes, I recommend getting a custom curve made to optimize the output for your specific printer ink, paper, print setting combination.


Please let me know if you have questions, or there’s anything else I can help you with.
Best regards~ Dana :slight_smile:


#10

Dana,
Thank you for your help.
I’ll be contacting Inkjetmall soon about a custom profile.
Best Regards,
John


#11

Ok, sounds good- let me know if you have any questions about printing targets or if there’s anything else I can help you with.

Best~ Dana :slight_smile:


#12

While you were out I had custom curves made by Kelly. Things are back to normal. Thank you for your help.


#13

Ok, excellent- thanks for letting me know.

Best regards and happy printing~ Dana :slight_smile: