G7 Compliant Paper

[Skinflint]

Does anyone know of brands of paper that are G7 compliant?

 

[Bret Hesler]

The last one I knew of that was close was Lustro (LOE), but that is no longer being manufactured. There are a few that are on the outer edge, depending on which spectro is used to measure them (Sterling, Opus, Utopia)

Bret

 

[Skinflint]

Anyone else have suggestions on paper for G7 calibration?

 

[gordo]

The last one I knew of that was close was Lustro (LOE), but that is no longer being manufactured. There are a few that are on the outer edge, depending on which spectro is used to measure them (Sterling, Opus, Utopia)

Bret

Just be aware of the OBA (Optical Brightening Agents) content of the papers that you are considering since they can effect how your instruments read/misread your calibration forms.

best, gordon p

 

[Skinflint]

Just be aware of the OBA (Optical Brightening Agents) content of the papers that you are considering since they can effect how your instruments read/misread your calibration forms.

best, gordon p

Gordo,

Do you have any tips on how to locate the right substrate?
My thoughts were to use the stock we use most often as our house stock.

I'm not getting much help from paper merchants, they act like this is the first they have heard of G7. Do you know of any sources that can help me out?

 

[gordo]

Gordo,
Do you have any tips on how to locate the right substrate?
My thoughts were to use the stock we use most often as our house stock.
I'm not getting much help from paper merchants, they act like this is the first they have heard of G7. Do you know of any sources that can help me out?

Just a point of clarification, G7 is a method not a specification.
Paper mills and merchants use very different methods and metrics compared with what printers use. That being said, it's disappointing, given the interest and uptake of GRACoL 7/ISO 12647-2 that your paper supplier (probably like most paper suppliers) has not identified specific papers in their inventory that conform to the ISO specification.

I'm sure there are better ways, but in your case, I would ask for your paper supplier's swatch books so that you can measure the color of the paper yourself. For commercial printing your looking for a type 1 paper with as little fluorescence as possible and a nominal white point of 95 L* (+/- 3), 0 a* (+/- 2), -2 b* (+/- 2) (measured with non-fluorescing white backing).

You can get a qualitative idea of the amount of OBAs in the paper by viewing the samples under a cheap black light like this:

available for less than $10 at any shop that sell rock n' roll paraphernalia. You want the one that uses a fluorescent tube rather than an incandescent bulb.

While you're doing that, check the OBAs of your proofing paper relative to your press paper:

You're looking for a proofing paper that has similar OBA content with your press sheet.

hope this helps, gordon p

 

[Skinflint]

Just a point of clarification, G7 is a method not a specification.
Paper mills and merchants use very different methods and metrics compared with what printers use. That being said, it's disappointing, given the interest and uptake of GRACoL 7/ISO 12647-2 that your paper supplier (probably like most paper suppliers) has not identified specific papers in their inventory that conform to the ISO specification.

I'm sure there are better ways, but in your case, I would ask for your paper supplier's swatch books so that you can measure the color of the paper yourself. For commercial printing your looking for a type 1 paper with as little fluorescence as possible and a nominal white point of 95 L* (+/- 3), 0 a* (+/- 2), -2 b* (+/- 2) (measured with non-fluorescing white backing).

You can get a qualitative idea of the amount of OBAs in the paper by viewing the samples under a cheap black light like this:

available for less than $10 at any shop that sell rock n' roll paraphernalia. You want the one that uses a fluorescent tube rather than an incandescent bulb.

While you're doing that, check the OBAs of your proofing paper relative to your press paper:

You're looking for a proofing paper that has similar OBA content with your press sheet.

hope this helps, gordon p

Gordo,

Thank you very much for this information. You are a wonderful resource.

We are using EFI 2200 gloss proofing paper which falls in the LAB spec of the G7 "METHOD" (thanks for that clarification also).

 

[mglouis]

Very clever. Thanks Gordo!

 

[gordo]

Very clever. Thanks Gordo!

And when all else fails there's always: http://printplanet.com/forums/re-print/21097-getting-sign-off#post132376

;-) best gordo

 

[randy williams]

hello,I am a paper merchant and after doing some investigating I do not believe that you will find g7 compliant papers. The reason is that the paper is such a variable that it would be next to impossible to find the same grade of paper everywhere in the world. My understanding is that is why you need to understand the values of the paper so you as the printer can make adjustments based on the previous paper so that the printed image will have the same appearanceon the paper you now want to use. Your paper merchant can get you the value specs you need and then you can make your adjustments as long as you know the specs of the paper you are trying to match. I hope this makes sense

 

[gordo]

You are correct - AFAIK there are currently no G7 (or ISO) compliant papers.

But you say that "you [the printers] need to understand the values of the paper so you as the printer can make adjustments based on the previous paper so that the printed image will have the same appearanceon the paper you now want to use."

So what "values" of the paper are available from (you) the paper merchant? For example do you provide information/values about the papers you sell as far as hue (and variation), fluorescence, optical gain, gloss, ink absorbency, fountain solution absorbency, opacity, etc? And is that information included with the paper when it is shipped to the printer?

thx gordon p

 

[tmiller_iluvprinting]

Productolith Gloss Lab measurements are acceptable(pass) for G7(ISO).
Regards,
Todd

 

[tmiller_iluvprinting]

Productolith Gloss Lab measurements are acceptable(pass) for G7(ISO).
Regards,
Todd

GRACol(ISO)-excuse me.
Regards,
Todd

 

[chevalier]

For commercial printing your looking for a type 1 paper with as little fluorescence as possible and a nominal white point of 95 L* (+/- 3), 0 a* (+/- 2), -2 b* (+/- 2) (measured with non-fluorescing white backing).

You can get a qualitative idea of the amount of OBAs in the paper by viewing the samples under a cheap black light...
gordo p

Nailed it.

For proofing applications there are vendors like CGS-ORIS that offer optical brightener free proofing papers. These proofing papers are more expensive when compared to proofing papers with optical brighteners.

Gordo,
What are your thoughts on using proofing mediums with/without optical brighteners given that virtually all press stock has varying amounts of brighteners?

 

[gordo]

What are your thoughts on using proofing mediums with/without optical brighteners given that virtually all press stock has varying amounts of brighteners?

I'm a bit disappointed that "randy williams" the paper merchant hasn't provided any details :-(

@ chevalier
A few thoughts.

Know that OBAs are an issue - it can help you avoid a reprint.

Be aware that OBAs are being used in paper manufacturing (for press and proof) and that they impact the color you see. They also affect the measurements that your spectrophotometer reports. That AFAIK there are no standards for the UV content in the lights used in proofing booths, nor in the lights used in spectrophotometers. And that the UV content varies wildly in lighting systems.

Some printers use UV cut filters to cover the bulbs in their light/proofing booths. But ambient light - especially in the press room can easily contaminate the lighting used in the booth.

Also, be aware that press ink blocks the effect of OBAs. This means that the effect of OBAs or the UV content in lighting systems is greater in the quarter tones/pastels and lighter colors. So you might have a proof press sheet match under one lighting condition but a mismatch in the quarter tones under a different lighting condition. This also affects spectrophotometers when taking readings.

Trying to align OBA content in proofing paper and press sheet (as per the post you quoted) can help.

Asking paper manufacturers (press and proofing), standards organizations, and instrument manufacturers to come up with specifications and standards might help. Unfortunately there doesn't seem to be any print organizations that are interested in championing printer issues.

There's more info with pics on my blog here:

Quality In Print: Optical Brightners

start at the bottom of the page to see Part 1.

best, gordo

 

[chevalier]

I recently moved to a new Epson proofer with integrated spectrophotometer and an OBA free premium proofing paper. I am extremely happy with it but I just can't shake this lingering thought in my head that OBA free proofs vs OBA press sheets is not any better than inconsistent OBA proofs and inconsistent OBA press sheets.

Is that a logical thought?
EDIT: I have previously read this article on your blog as well as many others. I'm a huge fan of your blog.

 

[gordo]

I recently moved to a new Epson proofer with integrated spectrophotometer and an OBA free premium proofing paper. I am extremely happy with it but I just can't shake this lingering thought in my head that OBA free proofs vs OBA press sheets is not any better than inconsistent OBA proofs and inconsistent OBA press sheets.

OBA free proofs plus OBA free press sheets = good
OBA free proofs plus OBA press sheets = not so good
OBA proofs plus OBA free press sheets = not so good
OBA proofs plus OBA press sheets = tolerable

The important thing is that you know that the OBA content can have an impact. So when press sheet and proof do not align, OBA content becomes one of the factors that you investigate as a possible cause. Much easier, for example, to test for than immediately diving into profiles to edit to try and correct.

make sense?

gordo

 

[michaelejahn]

Compose D7-II Proofing paper - for InkJet

Compose D7-II Proofing paper - for InkJet

We are using EFI 2200 gloss proofing paper which falls in the LAB spec of the G7 "METHOD" (thanks for that clarification also).

I like the Epson Stylus Pro 4900/7900 /9900 best (because you can simulate spot colors with the Epson UltraChrome HDR ink set which includes an Orange and Green) - and paper is of course is a important factor.

I will not make any remarks about other vendors papers - I have not had the opportunity to test many papers.

I will say that many manufactures sell "proofing paper" for injet printers that suggest they are good enough for simulating GRACoL - but when you measure them with a spectrophotometer - they often fail to be 95 in the L (most read 92 or 93) and while most are 0 in the a, very few read -2 in the b - in fact, most are 0 in the b.

We contract with a manufacturer to create a custom paper for our customers who are stiving to simulate GRACoL on their proofing systems.

Compose D7-II Proofing paper 24", 36” and 44" x 100 feet with a 3 inch core;
Aprox L*a*b* values: L*= 95, a*=0.0, b*=-2.0 ; GSM 170

We would be happy to send you a sample sheet to read yourself.

 

[randy williams]

I spoke with just a few of the paper mills we deal with and they are willing to share some of the paper specifications being discussed here. As they say much of this is propriatary information and the concern is that it falls into the hands of a competitor. I know that sounds absurd but to them these are industry secrets. I would suggest that you could ask your paper merchant for a list of the most neccesary specs to achieve your goal and see how much each paper mill is willing to divulge. Is there a particular paper in question here as I will be glad to investigate. As I understand it the paper is going to be such a variable here that unless you and everyone else printing for a common customer agree on a common grade of paper this will be a tough task. I would also suggest that most mills have technical people that are willing to go into the field and see customers depending on your location and these folks will have a greater understanding of this than I do. If you want the ultimate tell your paper merchant that you would like to go to a paper mill, based on what I have seen there you will be able to get about any answer you can ask and have a couple of fun insightful days. Coated mills are the best. Regards.

 

[gordo]

@Randy Williams

Thanks for responding with your offer to investigate. I can't imagine any other so-called manufacturing industry where the specifications for its major raw material would be considered "secret."

A few questions...

What material specifications do paper mills not consider secret and would supply to paper buyers/printers? What material specifications are typically included along with the paper when it is delivered to the customer?
Do paper mills identify which of their product lines conform to print industry standards?

Productolith Gloss was offered as a possible GRACoL 7 substrate.

Is it manufactured with a target CIE Lab color for the paper? Does the mill have a published tolerance for color variation within the skid or by number of sheets?

Is it manufactured with a target level of OBAs for the paper? Does the mill have a published tolerance for fluorescence within the skid or by number of sheets? How is fluorescence or amount of OBAs measured and toleranced by the mill?

best, gordo