Tiny Dot-line on the OHP with Epson 3800

[Andrew Ren]

Greetings all,

my first posting...

Just start to print diginegs on the pictorico ohp for my Pt/Pd process.
I noticed that there are dot-lines all cross the board, 2 lines per group, 2mm apart from each other; then another 2 lines like that(2mm space) about 1inch apart from the other pair(2 lines).

I did a power wash on the heads, wasted quite some inks, reprinted, lines still there, might be less, I am not sure.

It's very subtle lines, you have to raise the ohp close to a light source to see it, but it did show on my prints!

I have been using Matte black for inkjet printing, just switched over to Photo black for the ohp, and also start to use silver rag, that way I don't have to swap between the inks.

I am using the QTR, Uni-directional, 2880dpi, auto on dither setting(?)

the lines to me is more like a surface damage, but again, not sure..

a feeding problem, a nozzle check?

Cheers

Andrew

 

[Colin Graham]

Hi Andrew, good to see you here.

Sounds like the infamous pizza wheel problem- the feed wheels leave marks in the wet ink. I got around it on mine but tweaking my emulsions for speed, ie needing less ink, so the ink would dry before it hit the feed wheels. there is also a way to do a custom paper profile and allow more time between head passes so the ink will dry, but others report varying degrees of success with that approach.

 

[sanking]

Hi Andrew, good to see you here.

Sounds like the infamous pizza wheel problem- the feed wheels leave marks in the wet ink. I got around it on mine but tweaking my emulsions for speed, ie needing less ink, so the ink would dry before it hit the feed wheels. there is also a way to do a custom paper profile and allow more time between head passes so the ink will dry, but others report varying degrees of success with that approach.

Sounds like pizza wheel marks to me as well. I get the pizza wheel marks with the QTR profile that I use on the 3800 with regular Pictorico, but I don't get them with Pictorico Ultra.

One easy solution is to feed the OHP through the front feeder because the pizza wheels are not used if you print this way.

Sandy King

 

[pschwart]

Greetings all,

my first posting...

Just start to print diginegs on the pictorico ohp for my Pt/Pd process.
I noticed that there are dot-lines all cross the board, 2 lines per group, 2mm apart from each other; then another 2 lines like that(2mm space) about 1inch apart from the other pair(2 lines).

I did a power wash on the heads, wasted quite some inks, reprinted, lines still there, might be less, I am not sure.

It's very subtle lines, you have to raise the ohp close to a light source to see it, but it did show on my prints!

I have been using Matte black for inkjet printing, just switched over to Photo black for the ohp, and also start to use silver rag, that way I don't have to swap between the inks.

I am using the QTR, Uni-directional, 2880dpi, auto on dither setting(?)

the lines to me is more like a surface damage, but again, not sure..

a feeding problem, a nozzle check?

Cheers

Andrew

These are actually pinholes caused by the pin wheels (do a Google search for "Epson pizza wheels") contacting the film surface before the ink is dry. The more ink you lay down the more likely you are to encounter the problem, so you might try using matte black since this provides a lot more UV density than the photo black. I assume you used the 3800 sheet feeder; you might also try the front feeder on the 3800.

 

[PVia]

Yep, use the front feeder. The matte black (which I use for digi-negs) does the same thing if using the auto sheet feeder.

You can use an 11x17 sheet of light cardboard as a base for the film to use in the front feeder, since the feeder likes to see a thicker media there. I put a few tiny pieces of double stick tape in a few spots along the edge, out of any image area, to help the OHP stick to the cardboard backing as it goes through the printer.

 

[Andrew Ren]

Alright everyone, front_feed then!

Colin, are you sure there is adjustment for the print-speed, amount of ink inside the QTR? I have to go through it again. I only familiar with the curve-setting panel.

Sandy, funny enough. i heard of the pizza wheel thing before, and even try to look for them on my print, as i though it is a mark on the print shape like a pizza ring. as for the ultra ohp, it might be able to hold more ink, so dry quicker(?) how is the exposure time on the ultra comparing to the regular ohp I am using?

pschwart, yes, you are right. I am using the rear sheet feeder. also I think I can get enough UV blocking power from photo black already. my highlights are almost pure white..


Paul, that's a smart trick. I will try it out this weekend.

Thanks All!

Andrew

 

[Colin Graham]

No sorry it wouldn't be in QTR interface, it's within the epson printer utility for setting up custom papers.. And I'm not altogether sure if QTR accesses the mechanical instruction directly from the Epson driver, or uses its own- so that trick might be a dead end with QTR> sorry I didn't think of that yesterday.

 

[sanking]

Sandy, funny enough. i heard of the pizza wheel thing before, and even try to look for them on my print, as i though it is a mark on the print shape like a pizza ring. as for the ultra ohp, it might be able to hold more ink, so dry quicker(?) how is the exposure time on the ultra comparing to the regular ohp I am using?


Andrew

First, so far as I know it is not possible to slow down the printing speed with QTR. You can slow down the speed if you print with the Epson driver but I don't think there is any way to do it with QTR. I actually asked this question on the Quadtone RIP group on Yahoo and so far no one has offered a solution.

Pictorico Ultra does hold more ink and dries faster. Unfortunately the base blocks more UV than regular Pictorico by about log 0.15, which amount to 1/2 stop more printing time. So an exposure of 300 units must be adjusted to 450 units to compensate for the extra base density.


Sandy King

 

[Colin Graham]

Also I think I can get enough UV blocking power from photo black already. my highlights are almost pure white..


Andrew

I think what Phil means is you can lower your ink density enough to get rid of the wheel marks using matte black because the matte ink is a more efficient UV blocker than photo black, and will use much less ink to block.

But for what it's worth I had problems with the MK ink and excessive grain on my 3800, so that substituted one problem for another in my case.

But looking at the profile you posted over on the LF forum, you have the LLK ink at 80, which sounds like a huge amount of ink to me, so maybe try getting rid of that since it's not a great UV blocker- or does it help with shadow separation maybe?

 

[Andrew Ren]

I don't know how much the role the LLK plays in my curve.

but as far as I understood what Ron Reeder says that. Boost_K is for the 0%, so I am fine with that..
Limit_K is mostly for the 0%-20%, I am fine on that too.
then the only part left for me is LLK and LK, as Colin said, the LLK is 80% and LK is @ 65% both pretty high already...

Don't know whether I should crank the LK even higher...

I attached them over here as well, just make life easier:


no curve text, run the install command QTR, got the nocurve.quad(first one)

my newly built correction curve.(the second one)

 

[Kerik]

Using both Pictorico and Inkpress film I've not gotten pizza wheel marks on my negs. As Sandy said, the easy solution is the front loader. Stay away from matte black ink on negs intended for pt/pd. You will likely see an increase in grain if you use it.

 

[pschwart]

I think what Phil means is you can lower your ink density enough to get rid of the wheel marks using matte black because the matte ink is a more efficient UV blocker than photo black, and will use much less ink to block.

But for what it's worth I had problems with the MK ink and excessive grain on my 3800, so that substituted one problem for another in my case.

But looking at the profile you posted over on the LF forum, you have the LLK ink at 80, which sounds like a huge amount of ink to me, so maybe try getting rid of that since it's not a great UV blocker- or does it help with shadow separation maybe?

Yes, that was my thought. But as Colin and Kerik mentioned, the matte black is much grainier than the photo black. I use photo black on an R1800 and it provides a much greater dMax than the 3800 photo black which seems pretty weak. I'd have to check my notes, but I'm not sure you could get a high density (log 3.0 or greater) neg on a 3800 using photo black. My recollection is that Ron uses matte black.
Sandy: did you switch to photo black?

The LLK in the profile Andrew posted does seem off the map at a limit of 80.
I have to find my calibration chart, but I recall that the LLK didn't provide much UV blocking. The trick is to maximize the UV blocking while minimizing the ink load

 

[Kerik]

When I first started with QTR almost 3 years ago, I tried matte black since that is what Ron had been using on his 4000 at the time (I think). I immediately abandoned it because of the grain issue. You can get log 3.0 with the 3800 Photo Black and the right ink mix and black boost. More yellow will help, too. Andrew got that profile from me (notice the KK in the curvename). In its original form it's a couple years old now and frankly, I don't remember why the LLK value ended up so high, but I do remember fiddling to get better shadow separation and maybe that was the reason for it. In any case, it works beautifully for me and many people I've shared it with. I'm not sure why Andrew is getting pizza wheel marks that show on his prints, but as Sandy said there's an easy fix!

 

[clay]

I think the rationale behind having a seemingly robust amount of LLK ink in the lightest areas of the negative is to enhance the smoothness that might otherwise be lost if the rasterization engine tried to create the same low transmission density with a optically denser ink.

If the rasterization engine tried to achieve a low average density with a high density ink, it would have to space the denser dots further apart. By using an ink with a lower actinic density, the rasterization engine will use more dots in a given area than it would if you tried to achieve the same effect with a higher density ink.

Which is one of the reasons, in my opinion, that QTR is such a superior method because it allows the user to specify and achieve a high degree of control over the ink distribution of the rasterization engine.

I have used this ability in QTR recently in making polymer gravure positives that have unusually high densities in the highlight areas that would be rendered almost clear using other approaches, just like we did back in the day of making traditional film positives for gravures that needed a density range from about 0.5 in the highlights to 2.0 in the shadows. You can get this same kind of density range using QTR without having to resort to an output levels adjustment that could potentially end up severely restricting the number of discrete levels passed to the printer driver.

At least that is the theory.

 

[PVia]

Kerik and Colin...

When you used matte black, where did you notice the grain? Shadows or midtones...or all over?

 

[Kerik]

Clay, that sounds like a good theory! Makes sense and the results speak for themselves.

PV as one would expect, the grain is most apparent in midtones and higher, especially in smooth toned areas like a foggy sky. Icky IMO.

 

[Colin Graham]

Yes same here, mainly highlights and the crossover areas from the light to dark inks.

Really can't say this enough, but I'm very indebted to folks like Ron, Kerik, Sandy and Clay for pioneering this workflow. I'd forgotten how frustrated I'd gotten with the whole process when I started- the mere mention of MK ink is a sobering reminder. Indeed, the only reason it seems so easy to me now is because of the work they have done paving the way. So, thanks very much for all the hard work and generosity.

 

[Kerik]

Colin, glad to hear of your success with QTR. But, put me at the end of that list. Clay was a huge help to me when I started with QTR and of course Ron literally wrote the book. Also, credit to Roy Harrington for creating QTR and putting it out there for a ridiculously low price.

 

[Ron-san]

Colin, glad to hear of your success with QTR. But, put me at the end of that list. Clay was a huge help to me when I started with QTR and of course Ron literally wrote the book. Also, credit to Roy Harrington for creating QTR and putting it out there for a ridiculously low price.

Friends-- I am both pleased and embarrassed to see some of my older pronouncements on QTR ink usage still being quoted (ie, use mK , not pK as the dark black and turn off LLK on the 3800). I am pleased because it means someone has been reading the manuals I have written. And I am embarrassed because the basis for making those pronouncements are pretty much out of date by now and I no longer especially believe them myself.

As you folks know, choosing inks and ink limits in a QTR profile means balancing several conflicting goals. We often need high UV densities, we want to use as many inks as possible, and we need to avoid overloading the Pictorico with liquid and we want the smoothest possible grain, etc, etc. To guide myself through this maze I initially used an old X-rite 316T densitometer to measure the relative UV blocking power of the various inks. I now think the densitometer was a useful, but ultimately inaccurate guide. A better way, perhaps, is to use the Calibration Mode in QTR to print out a sheet of all the printers inks, arrayed in steps from 0 to 100% of the machine limit (on transparency material, of course). Then, simply contact print that sheet onto a piece of paper coated with your favorite emulsion (pure palladium, whatever) using the basic exposure that you know gives you maximum black.

Looking at that contact print will immediately give you the most accurate reading of the relative UV blocking power of each of the inks. By this test I now find that (for the 3800 inset) LLK is NOT the weakest UV blocker. The weakest UV blocker is LM. So if you need to turn anything off to lessen the liquid load, it should be LM, probably not LLK. The other conclusion is that the action spectrum of a palladium emulsion is significantly different from the UV sensitivity of the 316T densitometer.

As to the choice between pK and mK as the darkest ink on the 3800, I initially went with pK since it was a much stronger UV blocker and I thought I could not get enough UV density with pK. Many of you have now demonstrated that, for palladium emulsions at least, pK is probably the better choice. It is quite possible to get enough UV density with pK and, for reasons that are still a bit mysterious to me, pK seems to give a less grainy print. Perhaps it has to do with the fact that pK is a weaker UV blocker and thus is less out of line with the other dark inks??

Anyway, I really appreciate the interaction and continuous feedback from the Hybrid community in our group effort to optimize the quality of digital negatives.

Cheers, Ron Reeder

 

[PVia]

I'd have to compare pk/mk prints side-by-side to see what y'all are talking about, as I don't see grain in my prints made via Ron's original info with mk. I use Arista OHP from Freestyle,a 3800, Fab EW paper and pure palladium with a hint of NA2.

 

[Ron-san]

I'd have to compare pk/mk prints side-by-side to see what y'all are talking about, as I don't see grain in my prints made via Ron's original info with mk. I use Arista OHP from Freestyle,a 3800, Fab EW paper and pure palladium with a hint of NA2.

OK, I have to admit that for my own personal prints I am still using my ancient Epson 4000 with mK as the dark ink. I know it has artifacts that have been cured in newer printers, but for most images it gives me a result that looks just fine. Sooooo. I am not really competent to comment on whether pK or mK is the less grainy on the 3800. But I cannot ignore the judgements of various other careful workers who say that they see a difference between mK and pK. Let each one make his or her own tests and draw appropriate conclusions. I am off to print more images! By the way, my website, ronreeder.com, has been revamped with a bunch of new images if you are interested. Cheers, Ron Reeder

 

[Colin Graham]

Sorry, did not intend to deride MK ink, just couldn't get it to work with my particular way of doing things. As always, individual results might vary.

 

[sanking]

OK, I have to admit that for my own personal prints I am still using my ancient Epson 4000 with mK as the dark ink. I know it has artifacts that have been cured in newer printers, but for most images it gives me a result that looks just fine. Sooooo. I am not really competent to comment on whether pK or mK is the less grainy on the 3800. But I cannot ignore the judgements of various other careful workers who say that they see a difference between mK and pK. Let each one make his or her own tests and draw appropriate conclusions. I am off to print more images! By the way, my website, ronreeder.com, has been revamped with a bunch of new images if you are interested. Cheers, Ron Reeder

Ron,

For the record I am using both the very old Epson 2200 and the somewhat less old 3800 for making digital negatives with QTR for carbon printing. The 2200 with a MK based profile gives very smooth grain, while the same profile with MK adjusted for Dmax on the 3800 gives very pronounced grain.

No idea why this is, but no question at all in my mind but that it "is". I for one am not going to go into metaphysical anguish about what "is" really "is". For me it is what it is.

I have tried every possible ink combination from here to there with the 3800 for making digital negatives for carbon printing, and whatever I do the MK gives really nasty looking grain. PK is much, much smoother, but there is the nasty issue in that to put enough of it down to get the needed Dmax I may get pizza wheel marks with the sheet feeded.

In any event, I am very much in your debt for traveling to Montana last year and teaching me QTR.

Best,

Sandy

 

[pschwart]

Ron,

For the record I am using both the very old Epson 2200 and the somewhat less old 3800 for making digital negatives with QTR for carbon printing. The 2200 with a MK based profile gives very smooth grain, while the same profile with MK adjusted for Dmax on the 3800 gives very pronounced grain.

No idea why this is, but no question at all in my mind but that it "is". I for one am not going to go into metaphysical anguish about what "is" really "is". For me it is what it is.

I have tried every possible ink combination from here to there with the 3800 for making digital negatives for carbon printing, and whatever I do the MK gives really nasty looking grain. PK is much, much smoother, but there is the nasty issue in that to put enough of it down to get the needed Dmax I may get pizza wheel marks with the sheet feeded.

In any event, I am very much in your debt for traveling to Montana last year and teaching me QTR.

Best,

Sandy

I have tried every possible ink combination from here to there with the 3800 for making digital negatives for carbon printing, and whatever I do the MK gives really nasty looking grain. PK is much, much smoother, but there is the nasty issue in that to put enough of it down to get the needed Dmax I may get pizza wheel marks with the sheet feeded.
This is my experience, too. At the moment, the negs produced on my R1800 using PK with the Epson driver are superior to what I can achieve with the 3800, but I haven't given up. QTR may make it possible, but it sure doesn't make it simple:rolleyes:

 

[pschwart]

I'd have to compare pk/mk prints side-by-side to see what y'all are talking about, as I don't see grain in my prints made via Ron's original info with mk. I use Arista OHP from Freestyle,a 3800, Fab EW paper and pure palladium with a hint of NA2.

I can see the MK graininess just by viewing the neg on a lightbox. It clearly shows in prints, too, but some subject matter and paper surfaces may mask the grain. Beware sky and flesh tones! Carbon transfer on photo paper is the acid test as this reveals all defects.