How does the P900 know which ink to use?

[Eric Brody]

I just purchased an Epson SC-P900. It will replace a wonderful 3880 that has not given me a bit of trouble in the 10 years I've owned it, clearly one of Epson's best machines. I succumbed to the instant ink switching, matte to photo and back, and the recent announcement by Roy Harrington that the QTR RIP now works on the P900 with matte paper.

My question is how does the printer know which ink to use?

I assume it decides based on which paper is chosen on the control panel.

The reason I am asking is that when I use the QTR RIP, latest version, the printer dialog gives only one option, photo black; there is no option for matte black. If the choice on the printer overrides this, fine, if not, I've got a problem.

I read the entire manual for the printer, the tutorial for QTR (which I've used for many years) and googled "how does the P900 knows which ink to use?" and did not find a solution.

Any thoughts from P900 users would be most welcome.

[digitaldog]

AFAIK, it switches based upon the media settings chosen (certainly with the native driver).
Does QTR (which I have never used) have communication with the control panel? You'd have to ask them.

[BobShaw]

Assuming it is the same as the P800 then the icc profile specifies it.

[digitaldog]

Assuming it is the same as the P800 then the icc profile specifies it.

How? Certainly with custom ICC profiles?
Now media settings, that's a different story.

[KeithR]

I use the QTRgui(windows10) printing with Piezography Pro on a P800. When I open the QTRgui window, I have the option to select PK or MK ink, or what's selected.
I also have the P900, so media selection will automatically select mk depending on what media selection is made when you load the paper. If I indicate, for example, Velvet Fine Art when I load Canson Arches or Rag Photographique, the printer will use Matte black. If I select Premium Luster Photo when I load Platine, the printer knows to use Photo Black.

[BobShaw]

It is in the Printer Settings. For Default it is Photo Black. Here I have created one for MK.
When you print the driver must read the base paper type and adjust the Printer Settings.

[Eric Brody]

Thanks to all. I wrote and received a prompt reply from Roy Harrington, the author of QTR RIP. He has recently rewritten the program for matte black on the P900. He told me that the "photo black" as the only option is obsolete and can be ignored.

[Ferp]

If you're printing through the Epson driver, that's where the MK/PK choice is made.  Except that most paper types don't allow you that choice - the Epson driver will force MK for matte papers and PK for glossy/semi-gloss papers.  QTR is a RIP and doesn't print via the Epson driver.  The MK/PK choice is made in QTR.  Roy had to find a way to send that selection to the P900.  He has only recently worked out how to do this.  Great work by Roy!

[MfAlab]

I remember Roy said P700/P900 did not use a PK/MK selector. The MK curve is located in the end of .quad file as an individual channel. That brings a new possibility, you can use both black in a single print if only you know how the .quad files work. Adding just a little MK in a glossy print could raise D max, Canon use this trick for many years, and now Epson imitates that. We could fine tune it by our own filnally.