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> Jon,
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> Thank you for your email and for helping me understand a little better how this all works. Our good friend Grant Kalivoda spoke to you yesterday about the problems we are having with this printer.
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> I don't think that the humidity is an issue because I have two humidifiers going all the time in my studio that is in my home. I don't have a way of measuring how humid it is inside but all the window have water drops on them most of the time.Â
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> The images that I am printing are black and white. I have been running tests with two different papers Epson Enhanced Matte and Canson BFK (using the Innova Smooth Photo curve) to no avail.
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> Grant, his associate Peter Ellzey and I have been troubleshooting this printer for several weeks now. We have been testing everything that can be tested. Today we are running test using my Epson 4000 to determine if the problem is the printer itself. This printer was working well prior to coming to me. At this point we working to isolate the problem.
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> One question that came up while we were working on the printer was "is it possible that I have a bad batch of inks, maybe with too much solvent in it? Is there any precedent of ink related issues?
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> It has been very challenging to get this resolved but I am not willing to give up using K7 inks yet. I really like the richness and the tonal qualities that these inks provide.
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> Thanks again,
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> Cecilia
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> --- On Sat, 1/5/13, piezobw wrote:
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> From: piezobw
> Subject: [QuadtoneRIP] Re: Banding-Cockling Problem in an Epson 7600 HELP PLEASE!!!
> To: QuadtoneRIP@yahoogroups.com
> Date: Saturday, January 5, 2013, 3:30 PM
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> Cecilia,
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> To give you a perspective of how K7 works. Normally with the ABW driver or traditional color printing through the RGB driver, the greatest amount of ink is printed when the tones begin to become very dark (about 65-100% density). The lighter areas are printed with fewer dots of darker shades of ink. With K7 produced media curves, with the exception of the black shade, each of the six lighter shades of ink is mostly printing at or near 60% density. Therefore even the highlights of a print have a tremendous amount of a very light shade of ink being printed (rather than dithering of a darker ink). The overall concept of K7 is to produce more reflection of interesting light back to the viewer's eyes and get a perception of depth and glow by eliminating the paper's involvement other than as a backing for the overall application of ink.
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> So density dependency in K7 is not related to image density as is traditional with 3 black ink systems. A K7 curve with seven shades of ink prints substantial density (and ink load) in the highlights and 1/4 tones. It has two additional shades of lighter black and two additional shades of darker black than does an ABW system. K7 does not need to "dither" in order to simulate tone. it instead lays down the appropriate shades of ink, and does so generously. So the cockling you are seeing is most likely very evenly spaced according to the rollers in the printer that are holding the paper down - and in relation to the paper expanding to quickly as it is slowly ejected.
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> In excessively dry conditions or with paper that has been stored in very little humidity (especially paper that is not designed for high ink loads such as Epson mattes), this amount of ink can produce this waviness. Epson recommends minimum 30% relative humidity for its print heads to function well. In the winter time when heating is used, it is not uncommon for a print studio to drop to single digits of relative humidity. K7 inks do not dry in print heads as readily as do Epson color inks. But, the paper is still subject to lack of humidity. New Mexico is rather dry to begin with. :(
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> If paper is stored in very dry conditions, the coating on the paper will not be able to absorb a lot of ink quickly. Worse, the difference between its dry state and its wet state is so severe that it reacts by swelling on the printed side too quickly as it expands when it encounters humidity (in this case...a lot of ink!). This becomes more prevalent as the scale of the paper increases. If you are using a thick inkjet paper designed for fine art printing such as JonCone Studio, Hahnemuhle, Canson, etc... you will be more able to avoid this condition in NM. If however, you are using very thin inkjet papers such as Epson mattes (any of them) or other thin matte inkjet papers - you will need to pre-condition them by storing them in environments that have sufficient humidity - and print in an environment with sufficient humidity. Check Epson's recommended humidity range. It is surprising.
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> What we do at Cone Editions Press is to run one or two Honeywell 6000 series humidifiers. For example, on Thursday we had -20 Æ' temperatures outside. Our heating system was running overtime. In our main studio we were able to maintain humidity at 30%. But, in an upstairs studio with an Epson 7900 color printer, the humidity had dropped to 3%. We moved a humidifier into the studio to condition the print heads - and that takes only about an hour or so to bring the room humidity up to 35% (minimum recommended by Epson).
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> In the old days of our traditional printmaking when we were producing multiple color serigraphs, we would lay our paper out on drying racks for days prior to beginning the edition process so that the printmaking paper would equalize to the ambient humidity of the print studio. If we did not do this, the paper could change in dimension over the first few days as it expanded or shrunk to match the ambient conditions. Paper, even inkjet paper, is very susceptible to environmental conditions. A tight roll of paper needs a great deal of time (in comparison to sheets) to adapt to the ambient condition.
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> If you store a box of paper in dry room with perhaps 2-3% rH and then bring it into a room which is at 65% humidity and immediately begin printing. You can expect some changes in image dimensions as you begin printing an inkjet edition as the remaining paper begins to absorb the ambient humidity and expand dimensionally. This may not be annoying unless you have pre-planned cut matts with very little margin for error.
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> So what can you do? K7 curves are not traditional QTR curves and do not respond well to the advanced controls of ink limiting. You could try printing on premium fine art media and see if you can live with dry conditions. You could invest in a humidifier for your NM studio. You might try looking at all of the K7 curves in QTR Curve-View and select one of the curves which produces less total ink. Not ideal - but a potential quick fix. For example, the K7 Epson Enhanced Matte curve prints with more ink than nearly any other curve. But, in very low humidity which you are probably experiencing in New Mexico winter, Epson Enhanced Paper has the greatest potential to cockle during printing with K7. A double whammy to be sure.
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> Hope this long explanation helps.
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> regards from extremely cold Vermont, but a warm moist studio...
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> Jon Cone
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> --- In QuadtoneRIP@yahoogroups.com, "laport47" wrote:
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> > I am an artist in NM. I am new to this forum. I have been printing with QTR for the past four years using the Epson 4000.
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> > I have converted an Epson 7600 to use K7 Piezography inks and have encountered vertical cockling in the paper traveling direction. What I mean by cockling is that the paper is getting more ink and solvent that causes the paper to swell (it is wavy) that repeats itself throughout the print. This problem doesn't seem to be density dependent.
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> > This problem seems to be that too much ink is applied by the printer in spite of the tonal qualities of the print.
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> > In the past the same files were printed in an Epson 4000, using the same inks and paper, with no problems.
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> > Any ideas, words of wisdom or solutions are very much welcomed.
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> > Cecilia
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