Question Weird spots in black print...

[ubeny]

Hi Everyone-

Has anyone experienced anything like this? [You guys have seen it all so I'm sure someone has! ] So, last week I noticed small white spots were showing up on my prints. They appeared to be random so I did my maintenance cleaning and sent the printer through a cleaning cycle. After that, most of the spots went away however, the ones that stayed where now in more of a systematic pattern... see pics attached. I printed large squares of each color and found that it only happens with black, no other color. C, M and Y print beautifully. After a couple of the large black squares, the issue appeared to go away. After a couple of large banners, the issue came back even worse and doesn't seem to want to clear up... again see pics attached. Nozzle checks are absolutely perfect every time though.

The printhead is new, the printer was accidentally reset a couple of weeks ago so I had to flushed the lines to get going again so that has been done. And this happens no matter what type of media I use.

Perhaps the black has gotten contaminated some how? I do use a bulk system so there's that. But wouldn't I see some sort of result of that in the nozzle checks?

Anyway, any help at all you guys can offer is very much appreciated!

Thanks so much!

 

[ubeny]

Anybody, anything? I'm taking any and all advice!

 

[Andy D]

Too much ink, when your ink limit in your profile is too high, your print heads put down more ink than can dry properly, so the ink pools up around every microscopic imperfections in your material. Either learn to run the ink limit test and adjust them in your rip program, or try different pre-packed profiles until you find one that works for your printer.

 

[SignosaurusRex]

Do you get the same pattern of holidays in the print on a different material? If not, give the material that you are using, a flash wipe of denatured alcohol with a clean cloth and then dry wipe and run another large area black test print.
If you are getting the same bad results with other materials... I'd say that you have contaminated ink.
I've seen this before and it turned out to be bad or contaminated media.

 

[SignosaurusRex]

Too much ink, when your ink limit in your profile is too high, your print heads put down more ink than can dry properly, so the ink pools up around every microscopic imperfections in your material....

The print samples don't appear to indicate "Too much ink" being printed (IMHO). The pattern of holidays in the print samples seem to indicate faulty media. I typically run extra heavy on the (K) with my prints on my Mutoh and have only seen this issue when printing bad media... regardless of color profile. with that said, It could very well be contaminated ink ...but doubtful in my opinion.

 

[ubeny]

Thanks for your replies Andy D and SignosaurusRex! Unfortunately this happens on any media I use... doesn't matter. I was thinking maybe bad ink also but I've been using this for some time now and this is the first time I'm seeing this. Plus, I was wondering would I get the same repeated pattern if that were the case? I'd be easier if there were an imager in that machine that I could point to as the culprit! My mind keeps going back to a head blockage even though the head is basically 2 weeks old. Like I said in the original post, it did it for a little bit and I ran it through a cleaning and it cleared up for a couple of prints then came back with a vengeance!

Thanks again guys!

By the way Andy D, I was born and raised in Hattiesburg... near Atlanta now though but love the Hub City!

 

[Solventinkjet]

I agree with above that it's usually contaminated or bad material in combination with possibly too much ink. Since it happens on all materials however, what type of ink are you using? Might be a bad batch. Also, if you flushed the machine to install the new head and any solution didn't get sucked out before inking back up, it can mix with the ink which dilutes it and causes issues like this. 9/10 times I see this though it's simply dirty or old material. How do you store your rolls?

 

[ubeny]

Thanks you for the reply! I have a paper storage room in my basement. It's actually pretty cool and dry down there. Both the Mutoh and the aqueous Canon Pro 4000 are located outside that area. It has been stored that way for quite a while now with no issues so this is kinda strange.

 

[ubeny]

Thinking about it, during this process, I actually unwrapped and printed on 2 new rolls of different media types (window film and adhesive vinyl) with the same results. I do have a couple of new vinyl rolls I just got so I'll take one of those out and try that when I get home.

Also, what is the best way to purge an ink line... I guess to pull fresh ink through?

 

[ubeny]

So I opened a new roll of vinyl and a roll of self adhesive, both I just got last week. Same results... very strange that I was printing well then this seems to just start out of the blue.

Thanks again for all who chime in!

 

[Andy D]

Is there anyway you could have solvent dripping/spraying/misting?

 

[ubeny]

Thanks Andy D! I guess... I mean that looks exactly like what those spots could be... but from where would that come? I mean I printed well for a while after the flush, then this showed up seems like out of the blue. I think I'm going to drain the black lines, change black ink cart and see what happens. Can't get to it until tomorrow but will report back with results.

 

[ewded]

crank up the heat and slow down the head, if that solves the problem then it's clearly too much ink / too low heat

 

[ubeny]

Thank you ewded! I can handle heat adjust in Flexi but how do you slow down the head on this machine. Sorry but really new to eco solvent printing and these printers.

 

[Joe House]

Have you lubricated your rails lately? I had a customer use too much oil, which then dripped for quite some time and left white spots on the media. Do you have an air vent blowing on the printer? Another customer did and it was blowing dust onto the media on the way into the printer. It appears to be somewhat linear along the feed axis, so I would look at points on the printer that cross where the dots are heaviest.
Do you get these if you just print red? Or just single channel colors? Cyan, Magenta, Yellow and Black. This might help you pinpoint a contaminated ink situation. Also have you changed the wiper lately? It may be wiping contaminants back on to the head? (sorry just typing as my head goes around in circles here)

Good Luck

 

[ewded]

Thank you ewded! I can handle heat adjust in Flexi but how do you slow down the head on this machine. Sorry but really new to eco solvent printing and these printers.

Easiest way is to use higher resolution, which make the head travel more. Or use unidirectional printing, both of these make the print slower allowing more time for the material to absorb ink.

 

[ubeny]

Thanks Joe House! Yes, I did recently lubricate the rails. Perhaps I didn't do the best job wiping off the excess. I'll definitely check that out! I didn't use oil though, I used the silicone grease. Does that matter? Also, when printing those color boxes, it only shows up in black... no other color has this issue. Yes, I also changed the wiper when head was changed.

Ewded - I actually did print 1440 and the dots still showed up although not as pronounced. I wondered why that was and what you mentioned about the ink absorbing is probably why.

 

[Andy D]

I don't see how it could be just contaminated ink, some of those spots are too consistent, & those "fish eye" spots
are exactly what too much ink looks like... Or like Joe said, it does look like dripping.

 

[Andy D]

 

[ubeny]

Thanks again Andy D! I am definitely going to revisit the rail lube for sure... but let me ask about the "too much ink" because a few have mentioned that. How do you regulate ink other than profiles? Can it be done another way. Can I tell the printer to use this profile but not "as much" ink as is being called for? I'd be cool if it's possible. Again, please excuse my ignorance on the subject.

You guys are great... Thanks!