Between 25 and 30 ml per square meter (1.0 - 1.2 ml per A4 print with a one-inch white border) is the figure I am arriving at with my Epson 3800 ... so I am wondering where the rumour is coming from HP printers consumed less than half as much ink as Epson printers do.
My last Z3100 log says 5.64 square meters and 56,69 ML used. This was mainly HM matte coatings and the highest inklimit setting the Z3100 knows = Fine Art etc>250 grams. Few small gloss sheets with gloss enhancer included. About 10 ML a square meter which is what I have seen in the past as well. With Gloss Enhancer over the entire surface this may go up to 15 ML a square meter but then the question is raised whether the GE should be compared to varnishing afterwards or to ink use by other printers that can not suppress gloss difference.
Twin packs 130 ML = 260 ML have a 30 Eurocents per ML without VAT price which is about equal to the 220 ML Epson carts and the 350 ML Canon carts ML price.
I think you need a RIP to lay down 20-25 ML a square meter with an average image, the driver doesn't in my opinion. I really wonder how the 20-25 ML per square meter ink use of a Z3100 got into this thread. I think my lousy Wasatch SoftRip may do that as it doesn't use a black generation as good as the HP driver.
On all other aspects, cleaning, ink switches, idle time, the Z3100 is frugal on ink, even compared to an Epson 3800 that will waste an average 6 ML on every switch cycle MK>PK>MK. The 3800 ink price is 45 Eurocents per ML excl VAT if I recall correctly.
According to my ISO and metric knowledge there are 16 A4 pages in an A0 page and an A0 page is one square meter. So your 3800 ink consumption is 16 to 19 ML per square meter and that square meter will have 4 cm white borders to get the equivalent white border your A4's had. My accounting says that your 3800 consumes 60% more ink in best case and the ink costs 50% more than what I have to pay. Not counting a Black ink switch here. In worst case the 3800 probably uses 3x the money a Z3100 needs to print a square meter.
try: [a href=\"http://groups.yahoo.com/group/Wide_Inkjet_Printers/]http://groups.yahoo.com/group/Wide_Inkjet_Printers/[/url]