Which uncoated profile for a high *-b paper?

[zcto7]

I am having an issue choosing an uncoated profile to aim for. The 70# uncoated paper I am trying to fingerprint measures out to Lab= 93.0/2.6/-11.9 using an eye-one without a uv filter and is 10.5 delta E from the requested value for paper type 4 in the bvdm 2006 manual.

Should I use the PSO uncoated profile and try to make it work as best as I can? If so when I go to find my SID lab values,should I subtract the difference from my paper and the requested paper to get the correct target values ( eg... add 2.0 values for the L and subtract 9.9) ?

Thanks in advance !!!!!!

*edit, most of our uncoated work is black grayscale photos and text, such as highschool winter/fall sports books, so the majority of the work is not critical but I want to strive for the best we can do. We only occasionally get 4 color uncoated jobs.

 

[TerryWyse]

b*+2.6/a*-11.9?? Wow, you got some OBAs (optical brighteners) going on there! I profile a fair amount of uncoated offset stocks but usually find them in the -6 to -9 b* range and maybe +1 to +2 a*. I would almost say your EyeOne is suspect or needs re-certified....at the very least, I would try to confirm that value with another spectro or spectro-densitometer like a SpectroEye or XRite 528 or similar.

As to your question, I've typically either used custom profiles from the press or, better yet, I've often used the Fogra 29 profile and simply edited the white point to match closer to the actual press stock. If you've got ProfileMaker's Profile Editor, it's a piece of cake to edit the paper white point.

One other thing, a lot of times I've gotten a better *visual* match to the paper stock using an average of a UVcut and No Filter measurement. Often the straight un-filtered measurement will result in a paper simulation on proof (absolute colorimetric of course) that is too blue visually....while the UVcut measurement is too yellow. Average of both filters seems to produce a more satisfactory visual simulation.

Hope this helps,
Terry Wyse

 

[zcto7]

Thanks Terry, that helps a lot!

I hope my eye1 is in good shape, here are some numbers I ran off from our type 2 coated and some 20lb copier paper. Is there some place online that will re-certify them or does it have to go back to X-Rite?

100# Cover Coated - L: 93.9 a: 1.6 b: -3.0
80# Text Coated - L: 93.7 a: 1.4 b: -3.6
20# X-9 uncoated - L:95, a:1.9, b: -6.4

 

[Mike Strickler]

You didn't say what sort of press this is--conventional sheetfed or digital? Fogra 29L is OK for uncoated sheetfed, not for a digital press. Profiling a conventional press is not something you'll want to do just for the occasional uncoated job. A white point edit can be done, but that would be a huge one. First verify the color of the paper--the numbers you gave sound extreme. If you want to send me a sample I can measure it for you and discuss what you might do next.

Mike

 

[zcto7]

Hi Mike,

Your right I did forget to list the press specs...that would help!!

We are running a Presstek 34 DI for the short runs and a 5 color Heildelburg MOFP (1985) for the longer runs. We are having color problems with the 5H and the DI matching so we where going to run some uncoated sheets while we are profiling for our coated stock. The main goal for profiling with uncoated is just to get a good image on the sheet without plugging.

The CTP plates are Kodak Themal Direct plates which makes it nearly impossible to linearize, which makes it harder to run the rip linear.

Unfortunately being a small shop, they buy whatever paper is the cheapest, resulting in a huge variance in paper color.

Some more readings off of two other heavy weight uncoated stock, which seem fairly normal. The 70# sheet looks waaaay bluer than these though.
80# cvr uncoated = 95/0.9/-3.2
100# cvr uncoated = 95.5/1.5/-6.2

*edit*
Being that my main concern is just dot gain and image plugging, would using a regular 29L or 47L profile be sufficient? we rarely do a high res proof of uncoated work.

 

[Mike Strickler]

Uncoated Profiles

Uncoated Profiles

Well, Fogra 29L is an approximation to start with, but it was made from press runs on conventional presses like your MOFP. Waterless systems like Presstek might show slightly different overprint behavior or dot gain, but by far the most serious issue is the fact that the paper is uncoated and has varying color. A modified 29L would still be the best bet in your situation. This does not mean that your proofs and press sheets will automatically match--that will depend on how closely you can run your presses to the Fogra 29 specs and how accurate your proofer is--but this should eliminate the gross problems you're complaining about, such as excessive dot gain and plugged shadows. When converting files to this profile for press output you'll find perceptual rendering intent to be the best overall choice to preserve shadow detail.

 

[martin.weberg]

FYI, FOGRA29 was replaced by FOGRA47L some time ago.

Martin Weberg

 

[Lukas Engqvist]

*edit, most of our uncoated work is black grayscale photos and text, such as highschool winter/fall sports books, so the majority of the work is not critical but I want to strive for the best we can do. We only occasionally get 4 color uncoated jobs.

On grey photos I'd keep them grey (with the correct dog gain curve, I suspect around 20%) and colour them with a CMYK 20 15 15 97 in indesign. This way you have much more stable images but still enough of the other colours to enhance detail and smooth out screening in the highlights.
The images must be tif or jpg for you to be able to colour them, note that this also makes them transparent so your frame colour will show through in the whites (this effect can ofcourse be set to good use)

If you decide to go with a "standard profile" you will want one with high GCR imho. Running grey images dependant on CMYK is asking more work.