Hi Mantinieri,
> For the production of my fine art portfolios, we have been using for the past 2+ years an Epson 7800 filled with 5 shades of gray ink (only carbon pigments, of course). Basically, it is the exact same setup Paul Roark ended up with after quite a long R&D (see his message #98675).
What was your clear base formula?
> After few hundred 17"x24" fine art prints on uncoated papers, the pro and cons of using this approach are coming to light:
>
> PRO
> 1) Smooth tones
> 2) Consistent results over time
> 3) Versatile and powerful with QTR driving
>
> CONS
> 1) Custom made base + carbon pigments clogs the dampers frequently (we change 4-5 dumpers/year)
I had Eboni-6 in my 7500 for more than a year and never had to change a damper during that time. (I did have to change one prior to that time, using more standard MIS B&W inks.)
> 2) Fine art printing daes not use the printer continuously. As a consequence, the plotter makes an automatic cleaning almost everytime we start a new print.
Did you consider using MIS's autoprint program to have the machine print a page every day?
> 3) Head clogging occurs with some frequency because of the carbon pigmens, the rare usage and the paper dust from uncoated media.
Yes, you have a number of variables. It's going to be tough to isolate them. I must say that the printers I have been using for more than a few years with the dilute Eboni carbon inks have the lowest clogging rate of any inkset I've used. The Eboni position will occasionally clog.
Dust from un-coated paper has been identified as an issue, but I'd be surprised if that gets into the dampers.
> 4) The dithering of Epson/QTr is inferior to HP's
But if the prints are perfectly smooth, is this an issue?
> 6) High cost of head replacement (about EU 800) that sooner or later will occur with custom inks (can you match the PH of the inks?)
So far, I've simply not seen any evidence with my own work with Eboni-6 that the heads are going to last a shorter time than if more common pigments are used.
I did go to the effort to match pH, and I concluded it was not worth the effort. The pH stays close anyway, and the centrifuge tests showed no advantage (maybe actually the other way around).
> 7) QTR is not a commercial product, if support is ceased, your workflow is broken
Possible QTR lack of support for the 7900 is one reason I bought the 7800. For un-coated paper you definitely need a rip. For coated paper, I can control all the Epson printers adequately (with appropriate inksets) via PS curves and QTR's Create ICC-RGB.
> ... considering the possibility to use an HP DesignJet 130 loaded with carbon inks for fine art printing.
That would be nice. Joe Berndt at Bowhaus in Los Angeles -- http://www.bowhaus.com/index.php4 -- converted to Canon printers. He has made a rip to support them. You might want to contact Joe.
> 2) Clogging is solved by replacing the clogged head with a new one while the previous is cleaned overnight with a detergent
> 3) Heads replacement is cheap
That is a clear plus with thermal printers.
> 4) Dithering of HP driver is smoother than the 7800
Again, is there really a visible difference?
> 5) HP support should be more consistent than QTR's over the years
You think HP will support a non-HP OEM ink solution? I doubt it.
> ... about one year ago, we invested in purchasing the following equipment to start some R&D during spare time:
> a) An Hp DJ130
That is a dye-based printing system, isn't it? I would think at a minimum you'd want to start with a printer that used a head made for the Vivera pigments.
...
> The rationale of the project is clear: finding a carbon ink a' la Eboni usable with HP thermal heads.
That's a very good goal.
> We considered two possible ways to do that:
> a) Diluting an already HP compatible carbon ink
Whether it's 100% carbon is debatable, but my gut feeling is that the HP Vivera MK is extremely lightfast. It also appears to be warmer than Eboni, which is the "problem" (for me) with all the carbon inks I've explored.
One thing that will be a problem with the thermal heads is their current requirement for inks with lower viscosity. The neutrality of Eboni probably comes in major part from its larger particle size. This is why it settles faster than normal. The lower viscosity base required for the thermal printer will exacerbate this problem.
> b) making the ink from scratch ...
> A quick search trough the internet shown that the ink base for thermal heads (being about 90% water) is much easier to make than that for quartz heads.
I'm not so sure of that. The Epson piezo heads are very tolerant of viscosity and other variables.
> We tested some Eboni in thermal heads and it did not work
> (of ourse), being much more viscous that HP ink.
I tried a reduced viscosity version in a Canon made for dyes and had results that were not competitive. But that Canon I tried was made for dyes. I think a minimum starting place would be to use a head made for pigments.
> Unfortunately, the spare time was quickly over ...
Likewise with me. So far, I continue to think Epson is the best platform for what we do. I'd look at some of the variables in your setup that could be causing the clogs and also some solutions that might exist.
I hope you continue your work with the 100% carbon printing. Finding solutions to it may be critical for the high end non-OEM approaches. The fade tests so far rank carbon at the top, then OEM, then there is a big gap to the others.
The accelerated aging tests I've heard described are simply inadequate. We just don't know what will happen to coated inkjet papers. (By the way, are you brushing your un-coated papers before using them?)
Paul
www.PaulRoark.com