Canon Pro Luster with custom profile has heavy banding in grayscale bar

[malantheon]

On of the reason I got i1Studio was, that I was not very happy with the performance of my printer (Pro-1) on the Pro Luster Paper (using only OEM inks so far). After I have created the profile, I could see the reason - more vivid colors, cleaner yellow and actual blue instead of purple. However, the custom profile also introduced heavy banding on the greyscale line. Is there anything that I can do about it? culprit?
The upper sheet is Pro Luster with Canon profile
The lower sheet is Pro Luster with a custom profile. The yellow forest is more accurate, so is the sky window between the rocks. The deeper upper row of color patches (the out-of gamuts) and slightly deeper red. However - look at the grayscale bar the ugly band there :-(

Thanks for any advice! Should I try to re-profile? I forgot to put white sheets under the paper when I was profiling - could that be the problem. The desk is wooden, light brown :-/

 

[palombian]

I had exactly the same phenomenon (on the same place) on my PRO-10 with 3th party grey.
It went away by changing to OEM ink (using the same profile).

What you show here with OEM ink makes me think I did something wrong too.
Even a 300g photo paper is translucent, white sheets underneath are necessary I suppose.

In your case I would make a new profile.

 

[Ink stained Fingers]

You both may be hit by a rare problem which gets reported even less, the i1 sensors - of the i1Studio and as well the i1Pro are prone to some stray light under those rare conditions - a rather iregular - luster - and very reflective surface ; i have seen this as well in the past on a few lustre type papers (3rd party), you get wrong readings which create a wrong profile which causes that banding at a particular color spot - here in the gray ramp. There is about nothing you can do - trying ro re-read the color patches - tilting the sensor slightly. I succeeded by using a different number of color patches - with the i1Profiler package - e.g. running 400 instead of 700 patches or similar, but the i1Studio does not give you that option.
I only came to this conclusion as I was reading some advertising text about the newer i1Pro3 sensor 'working more reliably on highly reflective luster surfaces', there is an optional pol filter available, and the sensor aperture is wider than on the older instruments.
You may run a test - trying to profile another type of lustre paper under otherwise the same conditions as you were profiling the Canon paper.
I don't know whether you are familiar with the Gamutvision software, it is not that easy to use when analyzing profiles, but it has a display option 'Black and White Density Response' which direclty would show an inconsistency there, you normally should see a rather straight and continuous line but most likely not with your profile.

 

[malantheon]

Thanks for the extensive information, even though it is not a piece of great news, I will try to reprofile

 

[Artur5]

Try @Palombian’s advice. Put white papers between the table surface and the paper you’re profiling, If possible, avoid plain paper (probably saturated with OBAs). Probably the best would be a thick sheet of white matte photo paper with the reverse facing upwards.
Also, scan the patches in an environment with low and diffuse light.

 

[palombian]

If the banding is not caused by the ink (feeding), then it must be a very unlinear profile.

 

[malantheon]

I just did reprofile it like you have suggested - in a very low light environment, main computer screen off, on stack of white paper (I did not use matte but other photo paper, not luster), I did not scale the patches down to A5 and went for full A4. The profile is now almost perfect (improved colors like in the previous case and linear greyscale almost indistinguishable from Canon profile, no banding, just a bit darker in the end - which could even be good). Thanks, everyone, for your help! Maybe scaling the print patches to save paper is not such a great idea after all... :-/ Soon I will be profiling Pro Platinum, even more shinier and reflective, so I guess I will stick to the proven routine for now.
I was on the verge of thinking the getting i1Studio was a total waste even if I got half price (i1 Pro 3 is really out of reach).

 

[palombian]

Maybe scaling the print patches to save paper is not such a great idea after all... :-h).

Who nows...
i1Studio aka Colormunki is very nice device.
You can print on any paper with any ink.

 

[malantheon]

I have i1DisplayPro I bought some time ago, back during the time I did not think I will be printing. To me, i1Studio just feels so "basic". But higher tier devices for hobbyist are clearly beyond sense. And it is an improvement over nothing, allowing me to get the most out of my printer.

 

[Ink stained Fingers]

Thanks for feedback @malantheon , your actions apparently helped a lot. It's not the glossyness overall, but some stray light reflections from the irregular surface of the luster (and simiar) papers.