Guidance on a matte spot varnish for text only

[Davino]

As a book designer, this will be a first time having to use a matte spot varnish applied to just text only. The UV LED offset printing process led to an unanticipated gloss/glare, and though we're keeping this glossier, saturated look for the photos where it's pleasing, it has to be eliminated on all text (a dense scholarly edition where shiny text is a hindrance to reading).

I'm putting together the InDesign file/pdf for this to be applied solely to text, which has both K body text and numerous sidenote annotations by scholars in wide margins that are printed as a dedicated pms spot in a special gray Pantone mix. All text needs to go as flat and matte as possible - exactly as the project was designed when expecting the typical result of printing on matte coated Arctic Volume White stock, conventional offset. We simply didn't know - and the printer did not flag - that UV LED means glossy results.

They're charging $1200 for 1 single sheet as a press proof testing this, adding they've never done this before so we must bear the risk. And is there a distinction between text "overprint varnish" (OPV) and text spot varnish? Both terms seem in use for this, but out printer uses the latter.

All input/comments greatly appreciated. Thank you.

 

[SteveSuffRIT]

Are you questioning the use of terms, the price, or the purpose of the press proof?
I would make sure they print a color bar of just the clear spot varnish so it can be evaluated.
For other readers, there have been other posts about this topic before.

 

[printerdan]

The $1200 reflects the printers desire to end the business relationship.

 

[Davino]

Are you questioning the use of terms, the price, or the purpose of the press proof?
I would make sure they print a color bar of just the clear spot varnish so it can be evaluated.
For other readers, there have been other posts about this topic before.

Forums need questions to be specific, and not freighted with overlapping concerns, so I apologize. The central concern is executing matte OPV on text only, well. Here's the Adobe InDesign forum's advice - do the print experts here concur?

"1. Registration spread: Ask the printer about spreading the varnish plate by ~0.05mm so the matte slightly overlaps the text edges. A matte halo is less distracting than a gloss sliver.
2. 100% tint only: Never reduce the varnish percentage. A halftone screen on the varnish plate creates grainy, mottled text. Solid blanket coverage only.
3. Overprint verification: Check Separations Preview in Acrobat Pro to confirm the varnish layer is set to overprint, not knockout. A physical test spread through the printer's RIP on the actual stock before the full run is the ultimate confirmation."

Claude A.I. offers: "Some printers prefer to control the spread at the RIP as they know their press's registration tolerance precisely and can apply the correct spread value there. Others prefer it built into the file." That's the detail-level input sought: build it into the varnish file by adding ~0.15 pt. stroke on text, or is it best for the printer to handle the spread?

 

[SteveSuffRIT]

You need to pay for a single form press proof to "see" the final production results of matte spot varnish over teh text only. Yes, of course, the matte varnish plate needs to be spread fatter to allow for misregistration.

 

[Davino]

You need to pay for a single form press proof to "see" the final production results of matte spot varnish over the text only. Yes, of course, the matte varnish plate needs to be spread fatter to allow for misregistration.

Spread fatter in the file the printer receives from us via increasing stroke on the letterforms for the varnish layer, or is this handled by the printer normally? The latter, I believe, but just to confirm.

 

[SteveSuffRIT]

Yes, let the printer apply their "spread" trap value at the CtP RIP.

 

[Davino]

Yes, let the printer apply their "spread" trap value at the CtP RIP.

The printer is having us create the varnish file with a 0.05 mm spread as opposed to them applying a spread trap value at the CtP RIP. It's a separate file in 100% K that they use for the varnish, according to their method. I imagine there are different means to arrive at the same end, but given they've said "we've never done this before," they may not be as versed in what's best. In the future, any text change requires updating the matte OPV file too.

The added complexity and cost of matte varnish on text keeps me up at night, but I’ve reviewed the prior test print under all lighting conditions, with widely varying results. Under flat, even lighting (e.g., in the modern Singapore subway tonight, cool color temp LEDs), it’s less bothersome; one suddenly wonders if this intervention is necessary. Then, in contrast, under a multipoint lighting situation (under dangling pendants, halogen color, well and adequately lit overall, but dynamic, not flat), the glare was an unmitigated disaster, utterly unacceptable, a night-and-day difference.

We’re moving ahead but may also let them run a sheet on Sappi Magno Volume in addition to the Arctic Volume White, with a portion of the Magno unvarnished just to verify if the glare is still as prominent. UV LED ink shine on text, on bright white Arctic stock, is a 1-2 punch to the eye where matte text would, otherwise, be ok. Magno may make no difference in terms of shine, but it's a less bright stock, less contrast, and may also reveal what their process does to Magno's natural texture. Recall it altered Arctic's (covered earlier).

 

[Kylin machinery]

Tight Registration is Critical: Because text involves fine details and sharp edges, even a fraction of a millimeter of misregistration on the press will make the typography look fuzzy, shadowed, or out of focus.

 

[Davino]

Tight Registration is Critical: Because text involves fine details and sharp edges, even a fraction of a millimeter of misregistration on the press will make the typography look fuzzy, shadowed, or out of focus.

On matte overprint text varnish, would you say this standard truth on registration applies equally as much, given it's a clear layer? Fractions of the shiny UV black ink underneath could show at the type's edges—would this indeed cause a fuzzy, shadowed, or out-of-focus look?

We'll soon see the results in our case (arranging for this test has taken additional fundraising and preparations, but is now almost ready to go to print).

It's astounding how much added work it's been to counter the shine of UV text ink. Toyo Ink (the printer's sole supplier) refused to resupply matte formulations such as they had 8 years ago. Seems a dire and dark truth of Toyo's industry, avoiding acknowledging UV printing's shine hurts readability; a devil's bargain for the other gains. Regardless, when it's glossy stock or shiny text ink, the resultant problem is the same and lay people—average readers—understand this:

https://www.reddit.com/r/mildlyinfuriating/comments/7vbbsi/the_glossed_pages_on_my_textbook_that_make_it/

 

[alibryan]

Forums need questions to be specific, and not freighted with overlapping concerns, so I apologize. The central concern is executing matte OPV on text only, well. Here's the Adobe InDesign forum's advice - do the print experts here concur?

"1. Registration spread: Ask the printer about spreading the varnish plate by ~0.05mm so the matte slightly overlaps the text edges. A matte halo is less distracting than a gloss sliver.
2. 100% tint only: Never reduce the varnish percentage. A halftone screen on the varnish plate creates grainy, mottled text. Solid blanket coverage only.
3. Overprint verification: Check Separations Preview in Acrobat Pro to confirm the varnish layer is set to overprint, not knockout. A physical test spread through the printer's RIP on the actual stock before the full run is the ultimate confirmation."

Claude A.I. offers: "Some printers prefer to control the spread at the RIP as they know their press's registration tolerance precisely and can apply the correct spread value there. Others prefer it built into the file." That's the detail-level input sought: build it into the varnish file by adding ~0.15 pt. stroke on text, or is it best for the printer to handle the spread?

No expert here but I do concur. Think of the type registration topic as (unless it's in a separate pass) being able to achieve the exact same results as the registration for every other color being printed on the sheet. In which case a slight spread of the OPV plate should be able to cover the type, nicely.

 

[turbotom1052]

I would suggest extreme caution when trying to overprint a matte coating or varnish on top of an already cured glossy UV coating. You might want to test print or at the very least draw down the matte on top of the already cured coating to check for adhesion and drying.

 

[Davino]

I would suggest extreme caution when trying to overprint a matte coating or varnish on top of an already cured glossy UV coating. You might want to test print or at the very least draw down the matte on top of the already cured coating to check for adhesion and drying.

But there is no separate glossy UV coating - it's the inherent nature of UV LED ink/UV LED printing that it cures on the substrate like glossy film (as opposed to our centuries-old conception of printing where ink absorbs into paper). Yet, the warning on matte OPV drying/adhesion characteristics on top of UV ink is noted, and is why the printer said they're not certain what will happen, and therefore from their end too, the test is a 100% requirement.

Hard to express how much, after years of work, this diversion, thanks to LED UV printing and UV curing inks that Toyo makes (withdrawing their matte ink formulations 8 years ago due to market forces), has caused. Never expected to become experienced in this, but circumstances forced it. One thing is certain: we (print book publishers, printers, the industry as a whole) cannot do serious scholarly volumes with shiny, glare-ridden text.

 

[Davino]

I would suggest extreme caution when trying to overprint a matte coating or varnish on top of an already cured glossy UV coating. You might want to test print or at the very least draw down the matte on top of the already cured coating to check for adhesion and drying.

The new wet proof has been received and it has a few surprises. Firstly, the glare reduction from the OPV on text is subtle and far more noticeable on the black body text than the many spot ink gray margin annotations that are critical, both equally important. The sheet was printed again on Arctic Volume White 130gsm, and on an additional sheet on Magno Volume 130gsm for comparison. Unfortunately they folded the sheets and shipped them this time in an envelope without any stiff backing, and so they had a fair amount of crumpling from handling/delivery which for assessing gloss/glare issues (the primary goal of this OPV test) made it hard. I referred back to the first wet proof to compare the differences side by side. It's been several months without viewing and I suspect that a new variable has entered the picture:

1. Gloss reduction over time Our first wet proof, stored for six months, appears noticeably less glossy than when first printed. Is gloss reduction in UV LED offset ink over months a known, documented phenomenon? I've found online possible explanations: post-cure continuing for weeks; wax and silicone slip additives migrating to the ink surface over time. Has anyone measured or observed this?

2. Matte OPV suppressing glare on black body text but not on Pantone grey annotations We applied the matte OPV to primarily to all text (letterforms, not flood coat) to address the UV LED gloss/glare problem on a scholarly text. I ran it on a portion of some photos as well just to observe its effect, and it's most noticeable there. The OPV visibly suppresses glare on the black body text but appears to have little or no effect on the Pantone Cool Grey 9C annotation text at 8.4pt. One documented explanation: lower pigment load in lighter inks means proportionally more vehicle in the ink film, and vehicle is the primary driver of gloss. So grey ink is inherently more glossy than black, and the OPV has more to overcome. Does this hold in practice? Is there a known solution?

3. Pantone Cool Grey 9C printing darker than a previous 50/50 9C/10C mix First proof, the printer mixed as 50/50 9C/10C — intentionally darker. Second proof should be pure 9C — lighter. It printed darker than the previous mix. Same press, same stock (the Arctic Volume White and the Magno Volume) both show it darker, and not all . No explanation from the printer yet. Has anyone encountered unexpected density increases with Pantone greys in UV LED offset, and what caused it?

Any experience on any of these appreciated.

 

[SteveSuffRIT]

Hi Davino,

Have you concluded that the 2 papers (Arctic & Magno) behave the same?

1. Gloss reduction over time
The mind/memory is not a good reference for color/visual appearance. You really need to have a numerical measured value for comparison, such as a gloss measurement. It's possible the gloss is the same as before, you just remember it differently. I doubt post-cure has any significant visual effect.

2. Matte OPV suppressing glare on black body text but not on Pantone grey annotations
I would expect this since gloss is related to color contrast. Visual acuity is less for smaller surface areas, such as 8.4 pt type/text. Were there any misregistration concerns fitting or hallo outlines? Was it all done in a single press pass?

3. Pantone Cool Grey 9C printing darker than a previous 50/50 9C/10C mix
The printing press color variation (ink film thickness & density) of this spot cool gray will probably exceed their visual color difference between them, #9 vs #10. Asking for a 50/50 mix to get a CG 9.5 is unrealistic. If the plate coverage is light, it is more difficult to control the ink/water balance on press, hence color variation.

Is the printer also performing the book binding operation in-house or sourcing out?
I wonder what your quality expectations will be for the mechanical finishing operations of cutting, folding (bleeds, cross-overs), signature gathering and Smyth sewn book binding?

 

[Davino]

Hi Steve,
Yes, Arctic Volume and Magno Volume seem to be behaving very much the same across all areas of concern:

a) Both still feel quite different from the sample A4 sheets received from Sappi and Arctic. Though we have had it confirmed no aqueous coating is applied, something transforms these stocks and changes their wonderful subtly tactile character during the process, either before or after printing. We covered this before and don't know what it is. So far, no one does.

b) Both stocks work well, with the Magno being a bit warmer. The degree of text glare and glare cancellation from the OPV appears the same. The printer says they have used them interchangeably on prior projects. Photo reproduction seems a bit better on the Magno, but I prefer the white point on the Arctic. As an experiment, we covered a side of the photos with OPV. It seems the OPV adds a hint of undesired warmth to the light areas of the B&W photos. Is that to be expected

1. Gloss reduction over time
Such a qualitative and subjective appraisal is entirely right to question, I appreciate that. Yet it's all I have to go off of. I'm sure you don't doubt I believe it's different - and I most certainly do (I wouldn't have gone ahead with these major costs and delays had the original glare been more subtle like it seems now on the original sheet). I originally photographed it under indoor and outdoor light at various angles - studying it at length before proceeding with this.

2. Matte OPV suppressing glare on black body text but not on Pantone grey annotations
No halo or misregistration concerns were raised by the printer about it, and I don't readily detect them by eye. This doesn't mean they don't exist. The OPV is a single pass, but are you asking if the black text and gray spot were separate passes, if that impacts this somehow?

3. Pantone Cool Grey 9C printing darker than a previous 50/50 9C/10C mix
Thank you for confirming that this level of precision between shades is unreasonable to expect.

Question: Would a flood coating approach (never a consideration until now as we were committed to preserving the natural tactile qualities of the paper) be a) less costly, and b) any more effective at knocking down text glare than the letterform OPV? Since the tactile difference between the original A4 sample sheets remains so great compared with the actual printed stock, I'm perhaps no longer committed to avoiding flood coating, if it's more effective and less expensive than the current approach.

I don't know if the printer contracts out to do the binding. From my end, everything appears to be handled by one vendor.

My expectations, we've learned, have extended beyond what's feasible in some areas. Now at this stage, I'm considering just running with Pantone Cool Gray 8C and possibly flood coating. Surprises with binding are going to be hard. The design is not very forgiving in terms of the margin between the gutter and text/material, with footers low on the page. There is a also a custom steel bookmark, produced independently for this title, that will be inserted by the printer in the gutter.

 

[SteveSuffRIT]

My feedback s below.

It seems the OPV adds a hint of undesired warmth to the light areas of the B&W photos. Is that to be expected?
Adding any varnish, coating (AQ/UV) or film lamination may change color slightly since they are not completely colorless, clear, transparent.

Gloss reduction over time
Unlike oil-based (sheetfed) and solvent based (heatset) inks and coatings, UV fully cured is 100% solid and there shouldn't be any significant post-cure effects. To quantify, you could ask printer to measure gloss on a lab drawdown proof, freshly applied and at weekly intervals, if time allows. Post-cure in my experience is mostly about physical, not optical, properties like rub resistance, slip angle, etc.

The OPV is a single pass, but are you asking if the black text and gray spot were separate passes, if that impacts this somehow?
No, your earlier concerns where the registration fit and possible hallo effect between text and spot varnish. Single pass is always best fit, multiple press passes can cause misregister.

Pantone Cool Grey 9C printing darker than a previous 50/50 9C/10C mix
The CIE Lab measured color difference, called Delta E, between CG #9 & #10 is only about 3.0 units. That's about the tolerance limit for commerical printing, packaging would be tighter.

Question: Would a flood coating approach (never a consideration until now as we were committed to preserving the natural tactile qualities of the paper) be a) less costly, and b) any more effective at knocking down text glare than the letterform OPV?
Yes, it should be less costly since there is no need for a dedicated plate, press unit, and make-ready/setup.
No, it will NOT be more effective than the spot varnish if they are the same material (formula). Usually, the spot varnish is applied on a printing unit so has a higher tack/viscosity. The flood coat is usually applied with a special coating unit (anilox flexo) and has a lower tack/viscosity.

Since the tactile difference between the original A4 sample sheets remains so great compared with the actual printed stock, I'm perhaps no longer committed to avoiding flood coating, if it's more effective and less expensive than the current approach.
This perception about the tactile feel is very similar to the perception about gloss lowering over time (post-cure, dry-back, dry-down). It's a subjective opinion. UV cures to a 100% solid film, like plastic! This may make the printed paper "feel" more rigid and stiff than the virgin unprinted sheet? An overall flood coat may make this worse? There are lab test measurements that can quantify this with objective values. Does the unprinted production paper "feel" the same as the A4 mill sample?

 

[Davino]

Since the tactile difference between the original A4 sample sheets remains so great compared with the actual printed stock, I'm perhaps no longer committed to avoiding flood coating, if it's more effective and less expensive than the current approach.
This perception about the tactile feel is very similar to the perception about gloss lowering over time (post-cure, dry-back, dry-down). It's a subjective opinion. UV cures to a 100% solid film, like plastic! This may make the printed paper "feel" more rigid and stiff than the virgin unprinted sheet? An overall flood coat may make this worse? There are lab test measurements that can quantify this with objective values. Does the unprinted production paper "feel" the same as the A4 mill sample?

Thanks again - very helpful, sharing your knowledge and experience. The unprinted production paper definitely doesn't feel the same as the A4 mill sample. It's not subtle or barely perceptible to me, and we left a larger test area (8 cm x 19 cm) unprinted to get a solid sense of this. After months trying to ascertain why the mill stock differs from the printer's, I've finally reached the point of conceding that we may have to leave this aspect unresolved, as we must start printing July 10. I've queried the printer multiple times at different points - they insist there's no other coating, AQ or otherwise, of any kind. You've tried to problem solve this as well. The A4 sample is simply and definitively different - and now it's confirmed that this phenomena happens on both their Magno Volume and Arctic wetproof stocks (I have A4 mill samples of both). The A4 samples each have a superb, very premium tactility to them - a delicate surface, one that seems like it wouldn't be forgiving. I had tested some text pages on the mill samples printed via inkjet, knowing it's wholly unrepresentative, but gives a general sense of what it's like to turn pages of text and see and feel the stock, a very rough facsimile that costs nothing to try. It was then that I noticed how susceptible the mill stock was to damage from just a drop of water. The stock's structure would collapse somewhat under moisture damage from any drop, and not recover when dry. The printed wet proofs, however, even in the unprinted areas, still show resilience, a degree of imperviousness to moisture damage. The paper is treated or altered in some fashion that lends it more durability. I suspect that the prior printer in Taiwan that refused to work with Arctic Volume stock without applying an aqueous coating or bringing me to sign off on accepting a high percentage of dirty/damaged copies, was making a similar assessment.

But with where things stand now, there are still some other areas I'd seek further reactions to. Since the premium tactile surface is lost, I don't hesitate to use a varnish. Their matte varnish seems to not alter the photos for the worse, and in fact seems very light, no change to the blacks or midtones, and only the slightest hint of a bit yellowing (still unwelcome but perhaps tolerable if it doesn't worsen over time).

The wetproof was damaged from their use of a non-rigid mailing folder (last time was a tube), making glare assessment on a sheet with folds, creases, and crumpled areas from handling in delivery, very hard. But I notice too that there is now ink loss on those creases, a destruction prone point in bending. See photos.

1. Would a flood coat yellow over time more than the minimal yellowing of the acid-free paper?
2. Would a flood coat provide better durability and prevent any of the surface ink loss, especially in the folds (there are some photos that stretch across the gutter - perhaps I should ensure there's no ink up to the Smyth-sewn points)

 

[Ezequiel]

Yes, that can happen, but I would make one important technical distinction: UV LED is not exactly a “printing process” by itself, nor necessarily a specific ink; it is a curing system. What changes is that the inks/coatings used must be formulated to cure under UV LED light.

That said, when printing with UV/LED UV inks, the ink tends to remain more on the surface of the paper because it cures almost instantly through a photochemical reaction, instead of drying through absorption and oxidation like conventional offset ink. That more superficial, closed ink film can reflect more light and create a glossier appearance or more glare.

In photographs, that effect can be pleasing because it increases saturation, contrast, and visual “pop.” But in text, especially in a dense scholarly edition, it can become a problem because the glare can interfere with readability.

So yes, it is entirely plausible that the text appeared glossier because of the UV LED curing system and the UV/LED UV ink behavior, especially on a matte coated stock. But I would not simply say that “UV LED always makes things glossy,” because the final result depends on the ink formulation, paper, ink density, coating, and press settings. There are UV/LED UV inks and varnishes available with lower-gloss or more matte finishes.

In short: the likely cause is not the LED light itself, but the behavior of the UV ink cured by LED on that particular paper. The printer should have flagged that the visual result could differ from conventional offset, especially for a project where text readability is critical.

Before moving directly to an expensive matte spot varnish press proof, I would first ask the printer whether they can use a low-gloss or matte LED UV black ink for the text itself.

Since UV LED is a curing system, not a finish by itself, the issue may be better addressed through the ink formulation rather than by adding a corrective varnish afterward. A matte or low-gloss LED UV black ink — and a low-gloss formulation for the Pantone gray text if needed — would likely be a cleaner solution than trying to spot-varnish fine type.

I would ask the printer to consult their ink supplier specifically for a “low-gloss / matte LED UV offset black ink” suitable for sheetfed offset on matte coated paper. At minimum, the supplier should be able to provide a drawdown or sample on the actual stock before committing to a costly press proof.

 

[SteveSuffRIT]

1. Would a flood coat yellow over time more than the minimal yellowing of the acid-free paper?
Yes, the UV coating can yellow over time, as well as the paper itself.
Be sure to spec with printer to use a non-yellowing UV formula to minimize this.

2. Would a flood coat provide better durability and prevent any of the surface ink loss, especially in the folds (there are some photos that stretch across the gutter - perhaps I should ensure there's no ink up to the Smyth-sewn points)
From the photos it's difficult to judge if the lack of ink adhesion is due to the ink itself or the paper coating/fibers surface cracking from rough handling and shipping? UV LED has less heat but heat can drive the moisture content (5%) of the paper lower, drier, making it more brittle and prone to cracking at the folds. You should not see any fold areas in a Smyth sewn book. We call photos that spread over both facing pages "cross-overs". These can show color variations (press) and misregistration (folded signatures, collating).