OCP Black and Green Inks are Driving Me Insane

[Grandad35]

...snip... And even MORE unexpected--no I'm not making this up--the quality of the black when printed is much better now than it used to be. Before, the OCP black on my photo papers had a noticeable bronzing when held at just the right angle in the light, and it looked visibly worse when compared with the Canon OEM black. The diluted OCP black, however, has almost no bronzing anymore, and is almost indistinguishable from the OEM ink black patches.

When adjusting the surface tension of the ink, bear in mind that surface tension provides the mechanism that delivers the ink to the nozzles and that it also plays a part in determining the drop size ejected onto the paper (both for thermal and piezo print heads). Could what you noted be explained by less ink being laid onto the paper?

 

[qwerty42]

Perhaps you would like to actually measure the viscosity and surface tension of the inks, so you can compare the values for the diluted inks to the values of the inks that function properly?

When I get some more free time I will try this and report back. I'm an engineer so this is the sort of thing I do for fun anyway I wish I still had some of the OEM Canon black to measure as well, for a good baseline, but I flushed it all out when I tried using its tank as a potential solution to the problem. I can tell just by eye that the black is of a higher viscosity, so it will be interesting to see how much higher it is, and what the final value is with the 25% water mixture.

When adjusting the surface tension of the ink, bear in mind that surface tension provides the mechanism that delivers the ink to the nozzles and that it also plays a part in determining the drop size ejected onto the paper (both for thermal and piezo print heads). Could what you noted be explained by less ink being laid onto the paper?

I think very likely yes, but as a consequence of the dilution primarily. With the diluted black, even though the liquid ink still LOOKS very black, its concentration has been reduced significantly. If there really was an issue with the ink being too concentrated, causing it to flow poorly, that means it also was delivering too much ink colorant onto the paper per drop.

Also, I'm not sure I made it clear in my previous post, but the final solution of ink I came up with had NO Formaflo in it; just distilled water. Thus the surface tension of the final mix was altered from the original state only by the addition of the water as a diluting agent. When I added the Formaflo on previous tests, the surface tension was visibly affected, while the printing problem showed no improvement whatsoever, so I decided that I was chasing the wrong variable with the surface tension.

 

[The Hat]

Why not just use Photo black instead of the pigment black and be done with it, you’ll never have any more clogging or ink flow problems to worry about using that..

 

[qwerty42]

Why not just use Photo black instead of the pigment black and be done with it, you’ll never have any more clogging or ink flow problems to worry about using that..

I'm not sure what you mean. As far as I know, this OCP ink (BK797) is a dye ink--not pigment. Is that not correct?

 

[qwerty42]

Warning, nerd content below.

I went ahead today and measured the viscosity and surface tension of the black ink using the approximate method suggested by PeterBJ and authored by Grandad35. The results were pretty interesting, showing as always why it's better to have measured values rather than just speculation.

Again, all values are approximate because the method of measurement is pretty simple and neglects some parameters, but it should be close enough for our purposes.

First I measured the black ink dilution which is working for me now -- OCP BK797 diluted 75% ink / 25% water.
Viscosity: 1.81 centipoise
Surface Tension: 36 dynes/cm

Next I measured the full strength black OCP ink, purchased last week:
Viscosity: 2.36 centipoise
Surface Tension: 31.7 dynes/cm

Since I was having this same problem with my old batch of ink, which was purchased in a large quantity in late 2010, I decided to measure it too. So this is OCP black, full strength, and a 4 year old batch:
Viscosity: 2.18 centipoise
Surface Tension: 29.7 dynes/cm

Finally, to give a reference point, I measured one of my 'darker' inks which has never given me any problems, OCP Red R122 (this was from the 4 year old batch, for what it's worth):
Viscosity: 1.95 centipoise
Surface Tension: 29.25 dynes/cm

What can we say about these results? Well, for one, the viscosity difference I was expecting to see with the black ink is real, compared to the OCP red. (I chose OCP red as the 'reference' ink because, by eye, it appears to be the thickest of the colors that have never given me any issues. This should be verified too.)

Also, the surface tensions of the new and old black inks are quite close to each other, as well as to the red ink. This explains why adding Formaflo didn't seem to help at all (in fact after 15 test pattern prints it seemed like things were getting worse).

The diluted black ink, which I mixed at 25% water to 75% ink as a stab in the dark, is now less viscous than even the red ink. However, the surface tension is increased, because of my adding water to it (water has a comparatively high surface tension).

I found a couple papers online that had methods for calculating viscosity and surface tension of two-part solutions, and made an Excel workbook to calculate these parameters based on the percentage of water used to dilute. If anybody is interested in it I can share it. Using this, it calculated a theoretical value of 33.6 for surface tension and 1.85 for viscosity of my diluted black ink. This is surprisingly close to the measured values of 36 and 1.81.

One step further, if I wanted to roughly match the values of the red ink: again using my spreadsheet, it looks like if I use 20% water in my black ink I'll end up with ~33.1 and 1.93 for surface tension and viscosity. These values are pretty close to what the red ink measured. I can't reduce the surface tension without adding some Formaflo, and I think the value is probably close enough without it.

One thing I don't know is if the printer handles all colors equally while printing, in terms of nozzle firing. If not, then matching the parameters of my trouble-free red ink might be the wrong approach. The best would be to get another OEM Canon black tank, and see what it measures, and then try to match that.

Josh

 

[PeterBJ]

I'm not sure what you mean. As far as I know, this OCP ink (BK797) is a dye ink--not pigment. Is that not correct?

It is correct. The Pro 9000 is dedicated photo printer which uses only dye inks. Some all-round models like the Pixma 5200 also has a pigment black, which is used only for plain paper documents. The benefit is a clearer and sharper print on plain paper, but the pigment black is unsuitable for photo print, so the Pixma 5200 also has a dye black for photo print.

I remember a post by most likely Grandad35 or fotofreek about Canon dye black having different properties than the other dye colours to give sharper plain paper print, by making the ink spread less on plain paper. Could this be the explanation for the more viscous OCP dye black from OCP? Any comments please @Grandad35 or @fotofreek ?

I'm impressed by your measurements. I wonder if I could replicate them? I have syringes and blunt and sharp needles in various sizes and a stop watch. I could then test IS inks for comparison.

I checked the MSDS's for Canon and IS inks to find the physical and chemical properties. No surface tension is stated and Canon only states the viscosity for CLI-8 Bk as 1-5 mPa x s. This SI unit mPa x s should equal Centipoise. So not much useful info here, but an MSDS is not intended as a complete recipe for duplicating a product.

Here are links to Canon MSDS's and here is the MSDS for CLI-8 Bk. Here you can find an IS product number, which can be used for downloading the MSDS, and here you can download the MSDS for the CLI-8 BK equivalent WJ1109. I found no OCP MSDS online, but you can require one here.

 

[qwerty42]

I'm impressed by your measurements. I wonder if I could replicate them? I have syringes and blunt and sharp needles in various sizes and a stop watch. I could then test IS inks for comparison.

I'd definitely be interested if you do. It's not too terribly difficult using the methods Grandad35 described. The biggest thing I noticed that made results inconsistent was if the blunt needle used for the surface tension test was not held perfectly vertical. If you can, rigging up something to hold your needles vertical for both tests (rather than relying on your own hand-holding) will make the results a lot more repeatable and accurate. One other important note, which may be obvious, is using the same set of markings for both the water and ink when timing the viscosity test. If you use a different set of markings for one liquid, the fluid pressure forcing the fluid out of the syringe will be different between tests and will skew the results.

Thanks for the MSDS links. Those are quite interesting. I notice the Canon CLI-8 BK claims to include glycerin in its formulation, which would both increase viscosity and raise surface tension. However, the IS black says nothing about glycerin. Perhaps the dye colorants used by IS provide thickening on their own which produce similar properties to Canon's ink...?

This has now made me really curious what the Canon black ink would measure if I repeated this test with it. I might sacrifice the 15 dollars and go buy another Canon tank so I can measure it too.

BTW, I was able to re-profile the printer with one of my 13x19 inch papers today using the diluted black ink, and made a really nice 13x19 print of one of my photos with no inking issues at all. It's great to have the printer working now the way I always hoped it would before. Thanks again for everyone's help and suggestions

 

[The Hat]

I think I should stay out of this thread till I engage my brain a LOT more, obviously the wrong printer ! Sorry..

 

[Grandad35]

I remember a post by most likely Grandad35 or fotofreek about Canon dye black having different properties than the other dye colours to give sharper plain paper print, by making the ink spread less on plain paper. Could this be the explanation for the more viscous OCP dye black from OCP? Any comments please @Grandad35 or @fotofreek?

I don't remember making a post on that subject, but I seem to remember that @mikling posted something on that subject a few months ago.

 

[PeterBJ]

Thanks for the info. I guess you are right about a post by mikling. I also vaguely remember something like that. I will search for that post.