Why are light cyan and light magenta used in a 6 ink system?

[aCuria]

Epson made a claim that light cyan and light magenta were not needed on the 8550, because simulating the light inks is possible with their smaller droplet size

To their credit, the 8550 was reviewed to produce sharper prints than the G600, probably because of droplet size

However, these light inks have re-appeared on the 18100 / 18050 which also has a 1.5pl print head

Doesn’t it make more sense for them to use Red and Blue inks on a 6 ink system to expand the gamut? Or maybe red and grey like the G600? Violet?

Canon seems to be the one who needs the light inks since their droplet size is larger

(Canon uses red and grey and I think the droplet size is 5pl. Epson droplet size is 1.5pl)

 

[Ink stained Fingers]

that's the difference between pixel peeping and image viewing - you don't view an image with the nose on the print.
Light colors had a reason longer time ago with 4 or 5pl printheads on large format printers, and the age old R800 already showed it that you don't really need the light inks anymore. But there is still some user inertia only considering printers as 'photo' printers if they come with light inks, so Epson is offering such printer as the successor of the 1400 to the user base; the L1800 was not available in all business regions.

A red or blue or green ink is slightly- incrementally increasing the gamut, but - if at all - you only can see a difference in prints if you have an image with colors just in that color region to start with, you need to carefully profile the printer and you need to have prints to compare to, you otherwise won't see any difference.
Epson claims to meet 99% of some Pantone color range with the violet version of the SC-P5000, that is probably important for the printing business, but the question is how much of that performance you really need and how much you are willing to pay for it ? And don't forget that such claims only apply to a small range of papers.

 

[aCuria]

https://bermangraphics.com/press/wilhelm.htm

This interview was interesting, but it is also 20 years old:

1. 4-Ink Printers: Historically, 4-ink printers used cyan, magenta, yellow, and black (CMYK) inks. These printers could exhibit a lack of smoothness and granularity in lighter areas due to the limited ink colors available for blending. This could result in visible dot patterns and reduced color accuracy.
2. 6-Ink Printers: 6-ink printers, such as Hewlett Packard's newer PhotoSmart system, introduced the use of dilute magenta and cyan inks in addition to the standard CMYK inks. Before the PhotoSmart printer, light inks reduced ink stability but HP formulated new light inks that actually significantly improved stability, as these newer inks were less susceptible to fading on exposure to light. The extra inks allowed for a higher density of ink dots in lower-density areas, leading to smoother tonal gradations and enhanced color saturation. The use of dilute inks also reduced color desaturation that occurs due to the visual mixing of white space between ink droplets in 4-ink systems.
3. 7-Ink Printers: The newest Epson printers, like the 2200, 7600, and 9600, introduced a seventh ink: dilute black. This innovation brought two main benefits. First, in near-neutral areas, it allowed a significant replacement of color inks with black inks, improving accuracy in reproducing neutral tones. Second, the black ink's higher stability enhanced the overall stability of images and minimized color balance shifts. This setup also enabled satisfactory printing of black and white images, which was challenging before. Furthermore, the dilute black ink helped reduce metamerism, where a color print may look different under various lighting conditions. This improved the print's consistency and resemblance to human vision.

I am wondering to what extent Epson has fixed their light ink fade resistance, and what trade offs were made with their different ink sets sold today

 

[Ink stained Fingers]

And why can't I print photos on a 4 color printer ?

 

[aCuria]

And why can't I print photos on a 4 color printer ?

I currently DO print with a 4 canon inktank, it’s perfectly fine for documents (black text is not as dark as a laser print, but it’s good enough)

However for color photos, even on Canon glossy paper prints only look good for about a month before fading can be seen visually. After 6-12 months the prints have faded to the point where they no longer look like color photos (very low contrast faded sepia)

My second gripe is that I would like the capability to make larger prints, as long as it remains economical to do so compared to paying for prints.

The printer makers are probably doing some price discrimination around print size. Should an inkjet capable of A2 be many multiples more than one capable of A3, given that you can use the same print head and the main difference is using some extra plastic to make the print bed bigger?

Anyway I do eventually need a printer for a different location, and in Asia the A3+ capable L18050 seems suitable and is locally available. it costs the equivalent of 460 euro.

Using different inks is an option but then I would have to factor in the cost of some way to make color profiles myself. I don’t see any local businesses offering a the mail in profile service

 

[Ink stained Fingers]

even on Canon glossy paper prints only look good for about a month before fading can be seen visually. After 6-12 months the prints have faded to the point where they no longer look like color photos (very low contrast faded sepia)

What type of inks are you using - Canon OEM Chromalife100 or some refill ? Where are these prints placed - in direct sun or is there any other exposure like ozone - outside placement ?

 

[aCuria]

I am using canon GI-70 inks, they not good inks imo. Then again a large % of prints are documents

Photos are kept indoors outside of direct Sun. I clipped them to a fishing line. Not at all near the refrigerator or ozone source I know of

I notice that when prints are overlapped, the shaded area of the print will fade somewhat slower

There’s an air filter running in the room with carbon and HEPA filters so the air quality should be very good at least when the filter is running

 

[Ink stained Fingers]

I am using canon GI-70 inks, they not good inks imo.

That's the main culprit for your weak photo prints - the GI70 - in Europe GI50 - is a pretty weak ink in regards to fading, you are a hidden victim of Canon's business plans that not all customers get the best possible inks. I have tested the GI-50 ink about 18 months ago - it is no better than much cheaper 3rd party inks - sorry to disappoint you. (Epson is playing similar games) But you have an option - use the GI-53 ink of the G550/650 instead , that's the real Chromalife 100 inks, model/productc names may be different in your region - like GI-73 inks or GI-23 inks for the G620 printer or similar, look for the G550 photo printer and the inks for it in your region.

And if you think that pigment inks might perform better - yes and no - it depends like always on the ink/paper combination. I have sorted out several Wilhelm Research tests for this purpose

https://www.printerknowledge.com/threads/do-pigment-inks-fade-slower-than-dye-inks.15466/post-134801,

if you need the most longevity you may go for HP Vivera inks instead - and a matching printer for your upgrade plans.
Don't look for pigment ink compatibles - I'm not aware of any decent fading test of those.

 

[aCuria]

That's the main culprit for your weak photo prints - the GI70 - in Europe GI50 - is a pretty weak ink in regards to fading, you are a hidden victim of Canon's business plans that not all customers get the best possible inks. I have tested the GI-50 ink about 18 months ago - it is no better than much cheaper 3rd party inks - sorry to disappoint you. (Epson is playing similar games) But you have an option - use the GI-53 ink of the G550/650 instead , that's the real Chromalife 100 inks, model/productc names may be different in your region - like GI-73 inks or GI-23 inks for the G620 printer or similar, look for the G550 photo printer and the inks for it in your region.

And if you think that pigment inks might perform better - yes and no - it depends like always on the ink/paper combination. I have sorted out several Wilhelm Research tests for this purpose

https://www.printerknowledge.com/threads/do-pigment-inks-fade-slower-than-dye-inks.15466/post-134801,

if you need the most longevity you may go for HP Vivera inks instead - and a matching printer for your upgrade plans.
Don't look for pigment ink compatibles - I'm not aware of any decent fading test of those.

I do not really need “maximum” longevity, In the digital era longevity matters less than in the film era because I can do a re-print after 10-20 years. (Probably with a different image!)

I would be willing to trade off some longevity for prints that look better in the first 10 years. Ink cost and print size are also important, some prints are likely inevitably to be damaged by my kids and require replacement

However the GI-70 inks are ridiculously bad for photos, it is a waste of expensive OEM paper if I need to re-print every 6 months

Is there even a good way to swap inks in a CIS printer? I think letting the print lines run dry is a bad idea, so I would end up with mixed inks. The pigment black is also useful for the documents

 

[Ink stained Fingers]

I must admit I'm a kind of loosing the view what you are really after - is longevity a concern or not ? Get the GI-53 inks and test them. You take the current inks out of their containers and fill in the GI-53 inks instead and do some image prints, the inks will mix just for a short while and the new inks fill the ink system instead of the old inks. Give it a try .

I would be willing to trade off some longevity for prints that look better in the first 10 years.

Quaility - what are your quality crieteria ? If it is color saturation you would need to test photo papers - or what else are you looking for ? I don't see a way to 'trade' longevity for some other parameters - it is - and I'm repeating myself - the paper which delivers you a large gamut or not but you need a decent ink in the first place - go and replace the GI-70 inks.