The main advantage of the Epson printers has always been that they use piezoelectric heads-- so they're physically pushing the ink out with pulses instead of heating it until it bubbles and pops like canon and HP do-- this makes them able to jet a huge variety of different inks, but also much more susceptible to contaminants like dust and the like-- also they're significantly more complex to manufacture, hence the nearly ~$2000 for a new head, and the reluctance to let the end user replace it themselves (they're somewhat coming around on this with their newer mid level industrial printers, like the newly announced F9570/9570H -- these for all intents and purposes have the same hardware as a P20570 (same head, bulk ink bag loading) but they'll be built around a more "pro level" frame (less plastic, more metal) and they have a user replaceable head routine. Also a $20,000 price premium over the fine-art model.
The one big issue faced when changing ink types is that different types of inks have different viscosities, and therefore require differently optimized waveforms to drive the piezo elements to the best of their abilities. It really is super fascinating when you get down to the nitty gritty of how these things work-- most industrial printheads are also piezo based, but they have slightly different designs based on their intended usage (in-head ink recirculation is a big one when you are dealing with white ink).
I must have forgotten about some kind of valve in the 4900 that prevents the inks from being pulled through by hand from the lines leading to the cartridges, because I wasn't getting anywhere with a syringe at the state I showed a picture of-- I ended up turning the machine on without the lines connected, letting it get into the ready position, then doing a power cleaning of all colors while the tubing was clipped into one of those water sealed bags that they provide with new maintenance tanks-- the printer "colosomy bag" as ive been calling it.
This head has a bad yellow channel (it looks like it must have hit something at some point and the face of the nozzle plate is literally chipped off on the side (they uses MEMS technology for these nozzle plates, which essentially is like a circuitboard PCB-- not the most durable material in the world-- at least with this generation of this "DX7" head (they hate those naming conventions) they altered the gluing system so that each indiviudal pair of nozzle lines is physically separated from the other 8-- this is a great idea if you're in a situation to take advantage of it (it used to be that once the nozzle plate started to delaminate ANYWHERE you were days/months away from the whole thing coming unglued and ruining your head). But they've never implemented a way for the end user to change one ink into another slot, so I guess it was just out of sheer engineering hubris? Anyway, I'm happy for it.
So i've decided to give up on the orange channel and just call this a (hopefully) 8 channel printhead for now. Thats plenty enough for my purposes for this project--
Basically I have a run of up to a hundred 9x12 metal prints to make, and what really makes it special will be the use of fluorescent pink and yellow. I know these are not archival by any means, but it fits the project specs well (it was an artist who used a lot of fluorescent paints).
I got the fluorescent inks from Cosmo inks-- they seem to be the only ones selling these besides mimaki and epson, and I didn't really want to buy 1-2 liter bags and cut them open since I probably will switch these inks out immediately once the project is done... or else I'll move on to my 9900 and convert that to do bigger dye sub prints.
thanks to @DBerg for the recommendation of the Ink Owl sublimation inks-- I'm not 100% confident about their archival nature, although Joseph from Ink Owl has been extremely helpful and believes that all sublimation inks are essentially the same (given the incestuous nature of the industry I wouldn't be surprised if they're identical to some other OEM's inks). But I will do a test compared to a chromaluxe panel printed with the Mimaki inks that I was using last time I ran a much bigger chromaluxe sublimation operation. And I do like that they have multiple levels of black. I'd love to try out their orange and green inks, but if this head can only do 8 channels or less, I'd probably end up going with something like CMYKLcLmLkLLk, or MAYBE orange/green instead of the light light black (I've found with some inksets, especially Epson's, that I've never needed more than one level of black to achieve acceptable smoothness. With Mimaki, Lk was a necessity, their reddish black was way too heavily concentrated to get away without a dilute version. And lest it's not obvious, dye-sub inks are dye-based, so there are no concerns about pigment buildup like with with the stuff i'm replacing.
