Need Help Fuji Acuity Prime UV gives noticeably thicker black layers

[titmouse]

For context, we use a Fuji Acuity Prime 20 printer with UV inks on white ACB (CMYK only), together with PrintFactory RIP software.
I have no formal education in printing, though I did follow a couple color calibration courses from our printer supplier.

A problem we've had for a long time is that the darkest tones form a very thick layer of ink, whereas lighter tones make a layer of ink that's probably just a couple microns thick. In comparison, the black layers are much thicker and the edges are easily felt by running your fingers over the print. In gradients, this creates a hard edge in structure (not in color!) which makes printed B/W photos look really bad.

To me it seems that the dark color generation is way too intense and absolutely piles on tons of ink to get the darkness level required. I think this might be related to the ink limit setting, but I can't seem to adjust it per channel and can only specify a total ink limit.

I've tried recalibrating, making an entirely new calibration profile, lowering ink limits and toying around with GCR/UCR settings, but to no avail.
Does anyone in here know what the problem might be & how I can correct this error?
Thanks in advance!

 

[balstestrat]

You know UV ink is always like that? I'm just saying don't expect it to go completely flat.

 

[titmouse]

You know UV ink is always like that? I'm just saying don't expect it to go completely flat.

Nope, I wasn't aware.

The layer thickness difference itself isn't a problem to us, it's just that it's got a very sudden onset and as a result, it creates very visible edges in otherwise linear gradients. The darkest ~15% of a perceptually linear gradient exhibits this sudden thickness increase.

I did notice some improvement in the newer color profile which made the edges more subtle, but it's still not anywhere near the smoothness where I'd like to have it.

 

[balstestrat]

Well welcome to UV. That's normal, it's what it is.

 

[titmouse]

Well welcome to UV. That's normal, it's what it is.

Welp, alright. It's at least good to know that I probably shouldn't waste more time trying to get around it then

On a similar note, do you happen to know what's the best way to deal with gloss banding? I hope it's not a similar kind of "that's just how it is" kind of deal but I fear the worst

 

[Ronny Axelsson]

Since there is (almost) no solvent vaporisation when curing UV inks, the ink layer will be thicker compared to other ink types.
This isn't all bad but may be a problem in some cases.

Sounds like the black is built up by a mix of CMY that is then topped with K, which creates this abnormal thickness.
Is it black only from the start or a "rich black" with CMY involved?
Or is it maybe an RGB black?
Check to see if there is a setting somewhere to reduce the amount of CMY in the black mix.
Is there a "preserve pure black" setting somewhere perhaps?

 

[Hamster]

Hi. I am not familiar with the Print factory profiler, but the essence is the same for everyone. Attach a photo of the black and total ink generation settings. Usually on uv total ink in the region of 220-280%

 

[swordguy3222]

The black limits in the rip might be set high. I know some rips have a black point compensation that dumps a ton of ink to make a rich black, but often it too much. I have never used Print Factory, but it sounds like your black limits are set high. You can also make your artwork using only 100K and not a 4 color black, that will reduce the blend of the black.

 

[Select Bulgaria Service]

Welp, alright. It's at least good to know that I probably shouldn't waste more time trying to get around it then

On a similar note, do you happen to know what's the best way to deal with gloss banding? I hope it's not a similar kind of "that's just how it is" kind of deal but I fear the worst

Clean the lamp glasses first If the printer is not new.
When installing a brand new Arizona 6170 Mark 2 I had a very pronounced such effect.
Here the glasses were perfect. New printer.
To a great extent, things depend on the inks and the material. Look for some mat mode. Try to align the heads to a perfect state.
This is a very nasty problem. If you have a choice of ink, try something more matte. The thickness of the ink also affects. The shape of the drop, the condition of the lamps. Density balance between individual heads in one color. The vacuum that holds the ink in the heads is also very important. The vacuum and if there are filters on the vacuum before the heads largely determine the size and shape of the drop.
You'll probably be able to ignore the problem, but it won't be easy. If the machine is set up in the best possible way, this problem should not be so visible.

 

[titmouse]

Hi. I am not familiar with the Print factory profiler, but the essence is the same for everyone. Attach a photo of the black and total ink generation settings. Usually on uv total ink in the region of 220-280%

I'm not entirely sure which of the settings I should send a pic of, so I'll just send whatever I can export.
The little peak at the end of the K splitting curve does seem like it may be relevant, but I don't think I can actually edit that curve now.
I have no idea what "splitting" even is anyway.
The total ink limit for this profile is set to 190%, I've also experimented with profiles with a lower ink limit (170-180%) which does seem to help a little bit, but the sudden transition to black is still very much there nevertheless.
As far as I've seen, I can't seem to specify an ink limit per channel, but I may not be looking in the right places.

Also, for context, we print photos, so large areas of single colors are rare.
I hope I've provided enough information

 

[titmouse]

Clean the lamp glasses first If the printer is not new.
When installing a brand new Arizona 6170 Mark 2 I had a very pronounced such effect.
Here the glasses were perfect. New printer.
To a great extent, things depend on the inks and the material. Look for some mat mode. Try to align the heads to a perfect state.
This is a very nasty problem. If you have a choice of ink, try something more matte. The thickness of the ink also affects. The shape of the drop, the condition of the lamps. Density balance between individual heads in one color. The vacuum that holds the ink in the heads is also very important. The vacuum and if there are filters on the vacuum before the heads largely determine the size and shape of the drop.
You'll probably be able to ignore the problem, but it won't be easy. If the machine is set up in the best possible way, this problem should not be so visible.

All printers involved are brand sparkling new, lamp glasses are cleaned routinely.
Head alignment is pretty darn solid and is generally not something I want to touch myself, not in the least for warranty reasons.
Unfortunately I can't choose different inks or any of the settings you mentioned.

 

[titmouse]

The black limits in the rip might be set high. I know some rips have a black point compensation that dumps a ton of ink to make a rich black, but often it too much. I have never used Print Factory, but it sounds like your black limits are set high. You can also make your artwork using only 100K and not a 4 color black, that will reduce the blend of the black.

See my post above, I've attached a bunch of screenshots with the settings from the calibration profile.

 

[Hamster]

"curve" select GCR, remove the "optimize" option

 

[titmouse]

"curve" select GCR, remove the "optimize" option

Optimize is already off, that part of the window is only used if Custom Black Point is on.

I've tried using GCR before and it didn't seem to have much of an effect, unfortunately.

 

[swordguy3222]

Are you making your profile in the rip software or using i1 profiler? Those curves look way off to me.

 

[titmouse]

Are you making your profile in the rip software or using i1 profiler? Those curves look way off to me.

Using Printfactory Calibrator, so in rip, yes.
They also do look way off to me, except I have no idea what they should look like

 

[titmouse]

Update. I've made a completely new profile from scratch and this time, adjusted the ink limits. A printing buddy gave me the tip to check the per-channel ink gradients with a spectrometer and take note of where the chroma levels off, then set the ink limit there. I've set my ink limits to 80/80/80/60 (total ink limit is 153), did a calibration and some test images.

The results were absolutely horrifying:

I checked on all printers, using the production calibration. All of them look like the left print. Whereas the profile I just made yesterday (on the right, with lower ink limits), looks much better. No weird dark border, an actual proper gradient, better contrast.

It looks like the original calibration that was demonstrated to us by the supplier never was made correctly. At this point in time we knew nothing & assumed the guy who they sent over (whose sole job was color management) probably knew what he was doing.
And apparently we never actually recalibrated from scratch and never touched the per-channel ink limits either.
I have no idea how we haven't found this sooner, it seems obvious in hindsight.

In any case, I got a total ink limit check chart at the bottom of this photo and I'm not sure how to interpret it. Should all color channels fade to black at the same column? At what color do I set the ink limit (ie. what on this chart is good, and what isn't)? Or should I set it to the point where channels reach their maximum chroma and brightness? There's no documentation whatsoever, so I just used the ink limit suggested by the software, 153.

(I think yellow is still a little bit too high, given the banding visible on all colors where it is used)

 

[swordguy3222]

I use ColorGate, so not sure how Printfactory works, but if I base what I know from mine to here then you should have your limit set around 189 or 198. You want to set it where there is no more visible change with any of the colours. With CG I have it set to 300, and mine looks like your 189.