Re: [Digital BW] Piezo v. MIS variable-tone versions [was Greetings -- 7000 (& 3000)]
2001-08-10 by Paul Roark
Frank, You wrote: >... I am ordering a CIS for my new 1160. >Do you have any recommendation as to the >Cone or MIS system being better >for variable-tone work? Short answer: I now favor the MIS version. Long answer: I tried to make them as interchangeable as possible. I want alternative sources and competition. The toners are essentially the same (1 part light cyan to 1 part light magenta to one part lightest gray), and the ink densities and positions have been matched on the 4-ink printers like the 1160. So the differences in the variable-tone versions mostly relate to the differences between the base inksets themselves. MIS inks are slightly warmer than Piezo inks. As such, the variable-tone MIS version has a little wider useful range than the Piezo version. The control curves for the two version are slightly different. The final neutral-version prints, however, look very similar. I'm not sure I can tell them apart. I took Piezo, MIS and variable-tone test strips with me on a trip through the Southwest. This trip included stops at U. of AZ Center for Creative Photography and a number of high end photo galleries, where I could compare the colors of these inksets to many classic prints and modern silver and platinum fine art prints. The MIS native color is very close to most of the platinum prints I saw. The Piezo native color was not seen in any classic prints. I saw one photogravure that was close. However, usually the Piezo print color (all test strips were on Archival Matte) looked too green. This color difference seems to affect mostly the warm versions of the variable-tone prints. In fact, the green is reduced even in the warm variable-tone Piezo because the Piezo yellow ink is not used nearly as much. The green seems to come from dyes in the magenta and yellow position inks. Of course (not to avoid the obvious difference) the MIS inks are much less expensive than the Piezo inks. In my tests, the MIS inks and the Piezo inks faded and color-shifted at different rates. Let me briefly explain how I do these comparisons. I have a florescent light tester that uses a brightness way above what is normal in display. The temperature is also somewhat elevated, but not hot. How the results relate to real-world display life is anyone's guess. However, the results do seem to correlate with the relative performances I and others have gotten in "south window" testing. I always made direct scanner (Epson 1600) comparisons of control test strips to test strips that have been in the fade tester at the same time, together. So, there may be lots of factors/variables, but I think I've equalized them for at least the direct light-fastness comparisons between inks that have been in the tester together. I'm satisfied that the results are useful enough that I base my decisions on it as opposed to the less controlled "south window" tests. (And life is too short to wait for Wilhelm.) When I graph my results, the patterns I see look a whole lot like the graphs RIT gets -- see the MIS tests, for example. The results of these fading and color shifting tests, comparing standard MIS to standard Piezo prints on Epson Archival Matte, are as follows: At 100 hours: Piezo looked better because it had color-shifted (warmed) 26% less than MIS. However, MIS midtones had faded 26% less than Piezo. At 200 hours: The color shifting at this point favored Piezo by only about 10%. So, visually, Piezo's edge was essentially gone. Piezo midtones had faded about 40% more than MIS midtones. At 300 hours: MIS at this point pulls ahead in all respects. The Piezo midtones had faded about 65% more than MIS, and the Piezo test strip had also color shifted about 25% more than the MIS test strip. I didn't go any further with this test. I think the pattern is clear. Visually, the color-shifting/warming is more of a problem than the fading. Many will not notice the fading in actual prints. However, I think they are both a result of the same process. When graphed out, the relative rates of change -- fading & warming -- for a particular inkset look virtually identical. I think that this color-shifting/warming is a real problem. However, I think I can control (virtually stop) the color-shifting in the initial warm-up period, whereas I don't think I can control the ultimate fading of the inks. Thus, MIS's ultimately better fading (and color-shifting) characteristics are more important to me. Where am I going with this next? I have one test strip with MIS inks with a special "counter-shift" mix added to the inks that is as cool in the midtones after 400 hours in the tester as it was the day it was printed. I'll focus on finalizing this mix soon, and it will be compatible with the MIS version of the variable-tone mix. No promises here, but I think I can control the warm-shifting to a great extent. (I'm leaning toward putting the mix in the toner so that the neutral and cool prints will stay that way, but the warm version will still warm-shift, thus allowing people to sun-warm their prints to achieve the warmer, almost sepia-like, tone that some people like. With this approach, those who want the counter-shift advantages can just switch to the new toner, hopefully without even changing to new control curves. It should be easy even with a CIS.) So, bottom line, I started with Piezo, but now my focus is on the MIS inkset. Price, suitability for hextone printers, interest in MIS in mixing the inks, and ultimate stability are major factors in this. (I think MIS's publishing it's RIT test results is also a real source of confidence.) (Frank, good to see you on this forum - hope all is well.) Paul http://www.PaulRoark.com