K7 kit and Shades n.6 pinkish


#1

I am a newbie in Piezography and I am starting to print with K7 inks.

I ordered the kit from Inkjetmall and I configured it on my Epson 9900.

I print on Photo Rag but I noticed immediately that Shade 6 was a little pinkish. I thought that I had a problem, maybe a contamination with the red Piezo Flush so I cleaned the print head again. I also doubt about my lightening and metamerism so I went outside to see the appearance under a sunlight: shade 6 was still pink!

At that point I tried this: I put some ink drops of shades 5,6 and 7 directly from the ink bottles on a rag paper and the pinkish was in the inks. See the picture attached.

I re-measured the calibration target of shades 5, 6 and 7 and Lab values of shades 6 are very different from all the other ones.

This is an example of some measurements (A and B are referred to Lab). You can see that all shades (I just wrote 5, 6 and 7 but the other four inks are perfectly neutral) are neutral with a close to zero negative value in A channel and a positive value in the B channel. The Shade 6 ink is positive in A and B introducing a little magenta cast)

Shade 5 A B

   		-0,27	   	2,75	
		-0,28	    	2,56	
		-0,31	    	2,26	
		-0,34	    	2,02	
		-0,36	    	1,64	

Shade 6 A B

		2,50	    	2,31	
		2,40	    	2,28	
		2,26	    	2,20	
		2,02	    	2,04	
		1,79	    	1,77	

Shade 7 A B

		 -0,62	2,30	
		-0,69	    	2,53	
		-0,75	    	2,72	
		-0,77	    	2,83	
		-0,74	    	2,77

Is it normal? Because I can see the pinkish cast in the light gradients ( I print on Hahnemühle Photo Rag 308 with the standard curve set) and it is also obvious on the printed target.

www.dropbox.com/s/kkrb25i7n3mmyxl/20180914_165459.jpg

Thanks for any help.


#2

This is normal and is a process that also happens when selenium toning in the darkroom.

Any of the shades can be mixed with their corresponding neutral shade to tone down the hue shift.

Oddly, your shade 5 is less magenta than it normally should be . . . . (5 and 6 are the split-magenta inks in this set.)

best,
Walker


#3

Thank you for the reply but it is still not clear for me how to ‘tone down’ the Shade 6 pinkish hue shift.
I need a perfect neutral print and I don’t understand why this is happening in a K7 kit that is called ‘neutral’.

All shades are neutra with Lab values around A = -0,5 and B = 1,5 only shades 6 is different.

Is it possible to exclude it? Or compensate with more shade 5 and 7? And how can I do it?

Thanks in advance for any suggestion.

Giuseppe


#4

So sorry. I miss-read this original post while traveling on the rd and thought you had the Selenium kit!

I have to verify some things on my end and will get you out a replacement bottle and cartridge ASAP. Sorry for the delay,
-Walker


#5

It is possible to replace shade 6 with shade 7 and re-linearize. This can get you going until we furnish you with a replacement bottle.

It would require printing of targets and a spectrophotometer. Do you have a spectro?

best,
Walker


#6

Thank you very much Walker!

I have a lot of spectros and I am quite skilled in color management (but not so in using QTR). Just tell me in which format you’ll need the data.

I don’t have a bottle of shade 7 to replace but I will order a new kit if needed.

If it is useful on the bottle of the 220 ml ‘pinkish’ Shade 6 there’s written

Lot# 160412
MFG: 07/10/18


#7

Thanks for the LOT #. I will check this ASAP.

best regards,
Walker


#8

Ok Walker please check it out and let me know how we can work together to fix the problem. The Shade 6 in that lot is clearly not neutral.

I need to order a new kit of inks so we can arrange all together, we work in Italy so it will take a loto of time to deliver the stuff.

I also need a “quick and easy” way to profile other paper such as Epson Ultra Smooth and Awagami Inbe Thick White. If you have any suggestion (or a kind of service by InkjetMall) that helps customers in profiling it would be very appreciated.

Thanks

Giuseppe


#9

I am PMing you on this.

best,
Walker


#10

IMO. The B channel on all of your inks is a little yellow/green.

Neutral Ink should be slightly negative in the B column to appear visually perfectly neutral.

New ink coming online soon. I finished 2018 shade 6 production this week.

Measurements at D50 from i1Pro and brushed onto Hahnemuhle Photo Rag.

Paper white: A:0.86 B:-0.42

A B
-0.07 -0.9
-0.08 -0.86
-0.12 -0.86
-0.17 -0.85
-0.19 -0.8
-0.21 -0.81
-0.28 -0.77
-0.15 -0.82
-0.3 -0.68
-0.02 -0.39
0.08 -0.43
0.02 -0.51
-0.06 -0.91
0.01 -0.91
-0.03 -0.91

Average:
-0.10375 -0.76625


#11

Hello and thank you for your PM. I did what you suggested and I re-linearized with no problem excluding shade 6 temporarily.
I am not authorized to attach files but if you write me at shop@fineartconnection.it I can send them to you for checking.
Thanks

Giuseppe


#12

I authorized you.

best,
Walker


#13

Here is the link to DropBox where you can find a double measurements of the linearization target before and after the exclusion of shade #6

Measurements linearized with and without #6 HPR


#14

Ok. Looks good on the A column. So now you can linearize it. I don’t see any of these measurements showing linear. Make sure to replace “,” with “.” before using the tool too.

best,
Walker


#15

Well I tried but I had some problem.

I started from the factory profile for K7 on PhotoRag308 (the original name is K7-NU-HANptoRag308.quad)

I remapped the ink set to my printer (Matte K on OR channel instead of K). Then I turned off shade #6 (on the LK channel) because it was pinkish.

Then I measured the linearization target you sent me and tried to linearize without shades #6 with your Excel file

It looks pretty good but I have a kind ok ‘posterization’ in the light part of the gradient as you can see from the attached pics.

How can I solve this?

Thank you

Giuseppe

https://www.dropbox.com/sh/jk3dt8sv0jizriq/AAAvpbJ38S7aphly6ba_VVSHa?dl=0


#16

You need to start with a different curve. Not the K7 curve, but the K6 curve.

Here it is.

K6-NU-UHD-MASTER.quad.zip (2.7 KB)

Map LK data to Y and then zero out LK. Print and linearize.

best,
Walker


#17

Thank you very much!

Now it works perfectly!

I have to linearize the same way other 2 papers: Epson Ultra Smooth 250gsm and Awagami Inbe Thick White 125 gsm, any suggestion on which is the best starting curve for them?

Thanks

Giuseppe


#18

Use the same curve. For the awagami you may have to limit the ink a little with the tool I sent.

best,
Walker


#19

Well that’s really strange. I checked my Neutral K7 dilution #6 and it isn’t different than the others, so it must be a batch issue.
But what I’m seeing in my set is really greenish results on all the papers I use,MK and PK - Photorag 308, Rag Photographique, Platine, and Hahnemühle Photorag Pearl. They are really greenish. I’m using the P2 k6 set up. Tonally they are beautiful . I haven’t relinearized the supplied curves because the ramp is really good. I used this inkset for 15 years on an Epson 10k and 7600 out of Studio Print and a 9600 out of QTR and did many portfolios with them that were totally consistent. I set this 3880 up with them to do digital negatives and wanted to make occasional k6 neutral prints so that’s why I chose the neutrals over the selenium set , that has much worse longevity ratings according to Aardenburg . I was then going to transfer this whole workflow to a 7890 with new heads that I bought for this purpose, neutral prints and digital negatives, but I can’t even think about that if the prints look like this green. Yes I did shake the ink carts thoroughly before and after installation. I know this inkset very well, or did, as I’ve made over a thousand large prints with it over the years. What I have here in the 3880 is totally different. Somethings not right. I guess I’m just going to have to use this set in the small printer for negs.


#20

My thinking is that you probably have something in your dampers if you are seeing this much green. These inks are 2013-2014 batch with stirring and additives included before bottle-fills to make them good but we have not seen color shifting aside from 2016 lot shade 6 which we replaced entirely on Monday just in case there were more bottles that were going magenta. IMO, this ink has always been “EU” green as the original formulation was built against “Illuminant A” measurements and not “D50” measurements on Hahnemuhle Photo Rag.

We have been printing this inkset here in our workshops without issue (not too green).

That being said, I’ve tightened up the AB values against the proper D50 standard recently and 2018 batch of this ink is dead neutral visually and will also be single-pass gloss. Entirely new formulation of my devising and done in small batch just like the pro ink.

best,
Walker