Well, "roller gap along with ink limits" are actually the first thing I checked into, and I am using the Thick FAP>250 setting and max ink - (Dmax looks good on the test except for the marks).
Because I was using a profile provided by Hahnnemuhler, (and because I had never used profiles others than those I had made myself before this), I had the thought to double check that setting also. It's easy to change the characteristics of a given profile in the HP Printer Utility, BTW. But it doesn't help, and IMO it's the combination of factors of rollers, ink and paper chemistry that are making the perfect storm for making these marks. I posted this because I was curious to know if others are getting this. It's so blatant in solid black areas in my case that you can't miss it. YMMV, but I'd like to know others status when it comes to marks. BTW, other Hahnnemuhler papers of near identical weight and "feel" print perfectly without any marks.
Anyone know if Hahnnemuhler has a customer support contact?
BTW, I brought this up with a tech at HP via the phone, but "I'm not familiar with that paper," and "I'm not sure if that paper is 'supported' with that printer" where the replies. For me every slightly non-standard end use of my HPZ is an episode of "Star Trek," with that "to boldly go where no man has gone before" parameter.
FYI, I'm using the HP postscript driver when this happens, and that is yet another "twist" because most people will be using the PCL3 driver. To my knowledge, the QUAD inks are only in play with the PCL3 driver but isn't that only with grayscale, but I'm not sure about HP's PK, MK variations. Come to think of it we should start a thread on the topic of "PK, MK & Quad Inks: Settings and Papers" on the HP Z & Zps, and see if anyone would be willing to enlighten us about that elusive topic. It sure has been kept under wraps, or else I am missing out because I haven't come across anything explaining this clearly. The shear number of variables goes off the chart and HP's helpful literature with reference to working with custom papers seems out of date with reference to firmware and model-the ps printer has always been a weird variant that is never addressed. Now that the Z3200 & Z3200ps are out, the Z3100 is the becoming a printer with "issues of abandonment." Sorry, but it's just too difficult to "upgrade" as much as the manufacturers want us to, and IMO, it's very unprofessional. I used my HP 2500CP for nearly 8 years.
Thanks for the interest, and so long for now, TOM
The media presets in the HP driver also influence the roller gap along with ink limits. Try the >250 gsm media setting on the bamboo. I once had William Turner on a large roll scratch from the bottom of the heads with the Hahnemhle Textured rag setting until I tried this thicker media setting. After that it was fixed. Not only that but the added dmax from that setting really helped with the large black backgrounds I was using. Really outstanding and smooth dmax. Some PK ink is added to the tritone when neutral black and white is being done. On this deep sepia edition it make the the older MK Epson prints I had made before look so weak in comparison. Since the Bamboo paper is not so great in the dmax area that might help you there also. But you might not care about that with this paper thought.