I set up to print an image with an applied ICC profile for Archival Matte paper, opening the JPG in Darktable to do so.
The printer is an Epson SCP600 which has two full black inks, Gloss/Photo black and Matte Black. The latter is the correct ink for the paper.
As the program started to drive the printer, the printer warned it was changing black to photo black.
Am I missing a control that lets me enforce a particular choice of ink, or prevent DT from changing it?
(Running on Ubuntu Linux)
I have this printer as well. And I like it a lot. I also wrote the North American manual for it 
Its the paper choice that changes the ink type, and that is controlled by the printer firmware, not by darktable. Matte/fine art papers get matte black ink, while glossy/photo papers get the glossy black.
I highly suggest you print in batches to avoid switching ink all the time.
That doesn’t happen with Gutenprint via the Gimp. The choice of paper is made in Gutenprint and sticks.
I selected the paper type in the print dialogue in DarkTable, matte paper.
The printer at that time had matte ink selected, having previously printed several previous images on matte.
I’ve been printing this “batch” for a couple of weeks.
It seems to me that an instruction has gone to the printer to change.
Adrian Midgley (Retired(Mostly))
The system printer dialogue was set for glossy.
Ubuntu: settings: printers–>
I’ll see if changing that has prevented the behaviour.
Later.
Wow I just looked at the current model of this and the printer cartridge set is almost 400 dollars US…how much printing do you get from these guys…
Quite a lot. My last one didn’t cost as much of that, in UK£. We change the set one cartridge at a time, and deplete different cartridges at sharply different rates.
There are also other systems of ink, which I’m not currently using, for instance by Permajet, Fotospeed, and Marrutt (and the 8 different blacks set from a very specialist supplier for very special monochrome printing) which can be used to refill their cartridges many times, or via a set of fine tubes from their quarter litre bottles.
And people using a great deal of ink are quite likely, I’d think, to be using it in a printer that can apply it to A2 or A1 or larger paper, those printers coming with big tanks.
@akm I am very surprised that you can use the P600 in Ubuntu at all, since Epson doesn’t support Linux. Have you installed a special driver for it? Do you use a color-managed workflow? Do the paper manufacturer profiles work?
I have the P700 and I was able to make good prints from Ubuntu using TurboPrint (a commercial driver), but that software was not very pleasant to use, I don’t think it could use standard ICC profiles and was limited in available rendering intents.
Not true: EPSON Download Center
I can only find drivers for very large format printers on there, like P6000 or P7000. I cannot find either the P600 or my P700. Nor can I find a Linux driver in the Downloads section of the printer’s page.
Epson doesn’t support Linux for your specific printer (nor mine) but they do have linux support for some printers. The Linux drivers are listed on the page I linked if you use the search. The Linux drivers are not listed on the product’s support page.
You can also extract a .ppd file from either the windows or macos driver and load that into CUPS.
The P600 etc are driven from the Mac by Gutenprint, just the same as Linux.
Adrian Midgley http://defoam.net/ http://defoam.net/photo.defoam.net/
darktable also has native support of Turboprint in the printing view, thanks to @Pascal_Obry