Grayish tone in GCO and paper white


#1

Hello,

I’m having an issue with my 9900/Piezography Pro printer and printing gloss with my Canson Platine curves. When I print with the 3 curves set to 100% neutral or dialing in some warmth, the white border area has very fine dots and grayish tone visible in the white border. When I print with the same curves set to 100% cool, there’s no issues with the white border.

I’ve verified that the border is pure white (i.e. 255/255/255) and have tested multiple images with the same results. We also printed the same images on matte paper (with a Photo Rag 308 matte curve) with no issues either. It seems to only happen with gloss printing with neutral or warm prints, not cool. Any ideas on what’s happening?


#2

I’ve taken a look at the Platine neutral curve and there is all zeros as the first numbers but for the GCO (LLK) channel. It shouldn’t be putting anything else but ink there. This actually could be a bug with QuadtoneRIP curve averaging that just has never been observed before. This is the first system to do gloss optimization with QTR as a same-time pass.

I suggest opening the curve in text editor and zeroing a few more of the first numbers in OR and GR channels. Do a small test print with the settings that were making it grey, and see if you see anything. I could be a problem with those channels.

Are you printing with an ICC or a without an ICC? If with, this can also cause problems in HLs.

-Walker


#3

Hi Walker,

Apologies, I should have mentioned this is a custom curve since we have a bad channel in the 9900 and had to remap the curves. We also added 5% extra GCO to help eliminate gloss differential. That said, these curves have been working perfectly for about 9 months now.

We are printing through print tool without iccs. I will take a look at the curve in a texteditor and see if the light inks or gco channels look strange and report back.


#4

I opened our custom curve with the extra 5% GCO added, and the supplied Canson curve that we remapped as our starting point. (Our yellow channel is bad, so we’ve remapped Y>GR). I checked and there are zeros at the first numbers in all the channels except the GCO channel.

I printed from both of these curves (the supplied Canson curve and our increased GCO curve) and had the same result with the grungy white borders.

I attached the two curves here in case that helps.

 

CFAP_curves.zip (7.3 KB)


#5

I’ve made some more prints, using the two attached curves and with some of the stock curves, with the same grayish tones in the border. Also tried with different images - same problems. Earlier last week when the problem arose, we cleaned the capping station and wiper blade to rule that out. (Didn’t change anything).

However, I did try printing the QTR purge image for my GCO channel in calibration mode. That printed fine without the grayish tone or dots appearing in the borders.

Any ideas if this is pointing to a hardware issue? It looks like when warm ink and GCO is being put down at the same time, some ink is bleeding or being sprayed into the border area. The only way to print so far without the dirty border is setting the curves to use 100% cool ink.


#6

The LK curve may be doing it.

I suggest zeroing out the various light curves and doing tests. If you find the curve that is effecting it, try zeroing out the first 5 highlights curves.

It could be a hardware issue, but more likely a profile issue.

-Walker


#7

After some more testing, I think Walker’s suspicion is correct that the problem is in the LK channel. I can’t get it to clear and see deflected nozzles that are bleeding over into an adjacent channel on the nozzle checks.

Our LK channel has warm:dark ink in it. Printing with 100% cool curve in shadows seems to eliminate the problem. The other sliders were set to 100% neutral for midtones and highlights. It seems to make sense, if using 100% cool for the shadows uses little or no warm:dark ink.

I uploaded the nozzle check - does this appear like a permanently clogged LK channel?


#8

Yikes. That is the classic nozzle de-lamination problem I’ve seen so many times with this printer. It’s not a clog because it can happen with any fluid in there, even PiezoFlush: it’s something to do with how the cleaning assembly and dampers (selector unit) interact during a cleaning.

-Walker


#9

We’re seeing this with the new sure colors too BTW. Just less often because they did change how the selector unit (dampers) works in those models.

 

-Walker


#10

I realized I mis-labeled the printout, my apologies. It’s the VM channel that is clogged; VM channel has warm:dark in it. The LK channel has cool:dark and seems to be printing OK. But yes, it looks bad and hardware related. Any suggestions, or does this look like the printer is toast? We already have one bad channel on it (Yellow) and were running it as a k5 warm/k4 cool printer. I suppose we could remove the warm:very light ink by flushing that channel, and then move warm:dark to it?


#11

VM is toast. Sorry for bad news.

K4/K4 will work (this was the original design of this ink anyway).

 

best,

Walker


#12

Hi Walker,

Two followups questions:

  1. Can 1 channel be flushed or are we looking at flushing the entire machine?

  2. To replace a 44" machine, what would you choose? My epson dealer has a refurbished 9900 that has never had ink in it. We found a used 9880 as well, but compass micro informed me that Epson is discontinuing parts for the 9800/9880s and beyond a supply of dampers, they don’t have other parts like the pump cap assembly anymore.


#13
  1. Flush one channel by printing the flush images (24x90 approx).

  2. If the 9900 has a new head that hasn’t had any color ink in it (Epson or otherwise, or at least not for long) I would spring for it.

-Walker