Dot Gain UV ink

[curiosity]

Have a look at this control strip patch. I don't like the finger-looking extensions around the dots. What do you guys think? It was much worse. A 50 looked like 90.

We began working on this problem when the 50% was reading 89%. We're now down to about 73-82% depending on density (1.3 - 1.6), but the dot still looks like it's splitting poorly or something else despite the density.
Paper is 12pt card C2S.
Here's what we've done so far to ensure compliance to UV ink use and got the better results:
- new 2 step fountain solution (PressMax 280 and HDA 64)
- new washup (bottcher offset uv)
- Gans UV ink (rapi-cure dense black)
- bottcher EPDM rollers
- bottcher uv blankets

febo'd rollers over weekend (rollers were swelling and haven't been febo'd in a long time); replaced at least one ink form roller due to flaring at ends; durometer reads were to spec on all; replace water form roller

 

[bbtommyd]

These might be stupid questions but I have to ask. Where are your blankets packed over bearer? How does the dot look on the plate, does it have that same pattern?

 

[bbtommyd]

These might be stupid questions but I have to ask. Where are your blankets packed over bearer? How does the dot look on the plate, does it have that same pattern? Give me a call if you like. 800 453 8242

 

[curiosity]

Good questions and I didn't provide all the details...it's a 640Komori and plates are set to .007 over and blankets at .001 under... .006 squeeze. However, haven't been checked in awhile. Definitely a must do.
And the dot on plate is round, not paint-ball splatter looking. (also the 50% on plate is a sharp checkerboard pattern. (Attached is it's pic)

 

[Deleted member 16349]

Good questions and I didn't provide all the details...it's a 640Komori and plates are set to .007 over and blankets at .001 under... .006 squeeze. However, haven't been checked in awhile. Definitely a must do.
And the dot on plate is round, not paint-ball splatter looking. (also the 50% on plate is a sharp checkerboard pattern. (Attached is it's pic)

Could this be a problem of having really weak ink? Just a thought.

 

[curiosity]

Could this be a problem of having really weak ink? Just a thought.

weak as in pigment strength? doubtful...dense black
weak as in tack? well, it gets thin quick from can to trough as it mills through the rollers

 

[curiosity]

Any feedback about how the dots look? Am I too picky in expecting better looking dots?

 

[Deleted member 16349]

Any feedback about how the dots look? Am I too picky in expecting better looking dots?

The dots look terrible. Looks like weak and/or low viscosity ink and maybe ink that takes up too much water. It is OK for ink to take up water but there needs to be a point where it stops doing that.

Just because the ink is a dense black ink does not necessarily mean that it is a strong ink. If an ink was strong, I doubt that one would see these filaments of ink going in all directions at normal print densities.

I was trying to find a photo of ink splitting research that I have seen in the past that showed the ink splitting forming finger like structures (not filaments) , but I have not found it yet. It seemed like it might be related to your problem.

Hopefully people who know more about inks can help.

 

[gordo]

Does this happen on other paper stock?

Gordo

 

[curiosity]

Does this happen on other paper stock?

Gordo

Yes. Most often used stocks are 100lb and 12pt, both CS2.

 

[Cornishpastythighs]

Just a few questions. Do you get this result with conventional ink also or just UV. Do you run special colours and are they worse than process colours.
I have seen these crappy looking dots when printing UV and we did all manner of things to try and print a better UV dot. The biggest improvement we got was switching ink companies and then changing from UV to Hybrid inks. They work great and you can wet trap if you wish and get all the benefits of UV. Not recommended if you are running foil or plastic though. We moved from full UV supplies to Hybrid blankets and Rollers where we can run UV/Hybrid/Conventional without changing blankets.
Our dots looked exactly the same as yours before we changed to Hybrid.

 

[curiosity]

We only get this result with UV. Black only as part of a 4/1 product (4c is not uv). Paper only (12pt and 100lb CS2). We tried hybrid from another brand with same results.

 

[curiosity]

We're looking into getting higher tack now.

 

[joyce]

I have seen this many times. Your fountain solution's solvency is tearing your ink uv apart. I would also think that your are experiencing misting. The problem is very easy to fix by changing fountain solution.

 

[Alois Senefelder]

God !

God !

Curiosity,


The answer is "Staring you in the face and on the paper" Emulsification !!!!



Regards, Alois

 

[tmiller_iluvprinting]

We have this issue with the black only. We run a different manufacturer's ink. The black dots tail when we get over 1.65 density. We see about 40% dot gain in the black when we have this issue. The higher the SID, the higher the TVI, and severity of the tailing.
Regards,
Todd

 

[curiosity]

I have seen this many times. Your fountain solution's solvency is tearing your ink uv apart. I would also think that your are experiencing misting. The problem is very easy to fix by changing fountain solution.

Do you have suggestions? we've tried 3 2-steps already

 

[Asures]

Do you have suggestions? we've tried 3 2-steps already

Just curious, which 2 steps have you tried and what doeses?

We have our own fountain solution chemistries / formulations that are made to run with specific ink and plate combinations. Have you tried calling your ink manufacturer (That would be me and or our staff) to discuss the problem?

It's a bit harder to help when providing tech support on the Web. I'm more than happy to assist!

 

[joyce]

Do you have suggestions? we've tried 3 2-steps already

ThinkSF at 4 oz per gallon. contact me at [email protected]

 

[curiosity]

My apologies for not closing this post with the resolution! And soooo long ago too.
Turns out that one of our guys used a cleaner that was not suitable for the UV rollers.
The rollers swelled.
We Febo'd the heck out of these for the next several weeks. Improvements were immediate, but took this long to return to our usual good looking dots.