Pantone inks mottling on offset stocks

[tambo]

Mottle appearance when printing Pantone colours on offset stocks. We tried three differennt ink manufacturers, different blankets but very little change. I've seen printed samples where colours lay down smooth on offset stocks, what's the trick? Premium stock will do it but is there anything else that can help to lay down the ink better without showing the fibers of the paper?

 

[Lukas Engqvist]

What colour are you printing? If the recepie includes a large amount of transparent white, wich is essentially varnish you shouldn't expect anything else on uncoated paper. It is a characteristic of a transparent ink on a rough paper. You may get a more pleasant result with a raster tone (with a fine raster) of a pantone colour with similar hue but at a more vibrant colour (ie the same mix with the exception of transparent white)

 

[Cold]

Mottle appearance when printing Pantone colours on offset stocks. We tried three differennt ink manufacturers, different blankets but very little change. I've seen printed samples where colours lay down smooth on offset stocks, what's the trick? Premium stock will do it but is there anything else that can help to lay down the ink better without showing the fibers of the paper?

Hi Tambo,

There are a few things I can recommend for you to do to help this.

1. WATER Mottle- Run as little water as possible in prior units. For example, if you were running 4cp and a spot color, excess water in the first 4 units will be present on the surface of the sheet when you lay down your spot color.

2. BACKTRAP Mottle - Every subsequent unit that hits your spot color can contribute to mottle. If it is not in the last unit, move it there and see if the mottle clears.

3. INK - I have had great success with stock related mottle, making an extra strong, low tack, semi-opaque ink formulation. Call your ink guy and ask him/her to make you up a 5 pounder this way. Tell him/her you want it with 10% opaque white(or 5% dry TiO2), 30% stronger pigment load, and a tack of 10.

4. INK- Double hit using an 80% screen and then 100%. This can help as well.

I hope this is helpful.


Cold

 

[u352]

Are you bumping on another unit? The more units I hit on offset stock the worse it looks.

 

[RGPW17100]

Stock plays an important part in the mottle. Cougar will print much nicer then wausau. Classic crest will do the same. Cheaper offsets are better for down and dirty black ink runs or types of things that have only line copy. Print on a color copy paper like hammermill or go with a cougar 70 lb and you should see improvement.

 

[D Ink Man]

Rather Easy Fix

Rather Easy Fix

Add 8% of 'Real Silver' (actually alumimum containing) such as pms 877. No imitation silver will do it. That is just enough silver to provide appreciable opacity without giving the spot color a metallic good. If you still aren't pleased with those results, increase the silver addition to 12%. This is the least evasive and effective way to try to mask the inadequcies of a low quality offst uncoated paper stock. Let me know how that works, if your time permits. D

 

[TheProcessIStheproduct]

never uses silver but a small amount of opaque white will also help, and it was already mentioned, but if it has a lot of trans white you have to run in last unit, if you run first unit and then 4CP it will look like CRAP...

 

[D Ink Man]

TheProcessIStheproduct> Response

TheProcessIStheproduct> Response

There is no doubt that running the spot in the last unit will help, but that is not always a luxury on a 6/C job with process also being run. Oft times it will mean that the inks, process and spots wil have to be moved to alternate running units to accomodate the objective. As far as opaque white versus silver, I will let you know, that silver has 30-50% more opacity, hiding power versus TIO2, opaque. That was not mentioned yet, but now it has. Transparent white should not have a bearing on the degree of mottle. Transparent white is generally softer versus the other companion pigmented bases #1. Secondly, if it is a matter of the spot being at a poor ink film thickness because of color strength, this is correctable. D Ink Man would be able to help you with all scenarios towards this subject line. I hope you gained a bit of education with this reply. My guess is yes. Respectfully. D

 

[TheProcessIStheproduct]

OK Ink Man, this is a bit off subject, but I have a big 4CP job plus 2 PMS, running on 5 color press, everything is in registration, I have run lesser coverage pms by itself then come back with process and other PMS, registration is OK not great because 2 PMS touch in logo so any bounce is real obvious, so I was thinking of laying down process black first then C,M,Y, and 2 PMS, which of two options do you like better?

 

[D Ink Man]

I would run the build process first, normal rotation. Then I would run, the two spot colors on the 2nd pass, with the heaviear coverage spot printing last and af far downstream, unit wise as practical, to avoid blank blanket/impression nips. Allow 24 hours before the 2nd pass with the spots. Of course this all governed by your inks setting ability, paper stock utilized and ink coverage with the four color. Hope this helps. D

 

[bky]

Reducing the line screen helps reduce the appearance of mottling.
When a dot varies in size or shape from the dot next to it, you can see mottling, particularly if the dots are varying because of small variations in the printing surface. Larger dots can help hide the variation, along with changing the dot shape. In some cases, elliptical dots can have a smoother appearance on uncoated papers. Angle may help here to: 0* to the feed direction could help minimize water issues (assuming of course, there are no other units being used with the Pantone to form a rosette).

I often run a Pantone plate at a lower line screen from the CMYK plates, particularly if there is a large area of a flat screen. High line screen seem to aggravate mottling (surface variation making a bigger printing impact as the dots get smaller).

 

[Alith7]

we run into this a lot when we have large solids on almost any offset stock, the grade and sheet helps a bit, but not always. Usually, it comes down to the press, and the fountain solution used. Our small 2-color Ryobi will mottle HORRIBLY because of the fountain system and solution used, whereas if we switch it to run on our 5-Color Heidelberg with a chiller and different solution that uses alcohol it looks MUCH better.

That's where I would start.

 

[hughy]

Hi Tambo-I am asuming you have ruled out stock by running a diffrent lift when this issue occured.Check out your water form at the time of print issue.Is it building up with imulsified ink? ,this will compromise your screen quality.If so check roller setting . Another thing to look at since you have said this is not a coated stock issue is are you running enough squeeze on your sheet. High bulk offset often needs additional impression squeeze to reach down into the lowest cavities of the stock.Motled print on offset can be misdiagnosed when ink transfere is not uniform through out the highs to lows on this type of stock.
Sounds to me like a press issue.The fact that ink and chemistry is not a issue on calendared
substrate pretty much rules out anything but press or stock.

 

[turbotom1052]

one thing that ive found that will sometimes help in a situation like this is to reduce the strenghth of the ink with either transparent white or with some gloss or satin varnish. This will weaken the strenghth enough to run a thicker ink film on your rollers. Of course you must now deal with the issues caused by this thicker ink film but it just might get you through the job. Also the suggestion to mix in something opaque will often cover up many issues. The thing is that by the time youve gotten around to mixing the ink more opaque youve allready moved the offending color down to the last printing unit. Overprinting an opaque ink on top of another ink thats allready down may cause issues of its own.

 

[Blanket Bob]

use a blanket with a soft shore A (48-50) of the face compound, and a low compresible carcass to drive the ink into the sheet. Blankets with hard face shore A, and a higher compressibility carcass tend to mottle on uncoated stocks.

 

[spigot]

ive tried the silver addition method and it works, but not always.
Lower screen lower film with much stronger ink works as well, or sometimes ill just cheat and reduce the ink down a fair bit with liquid/jelly reducer and smash it with heaps of impression. Doesnt always work either but lately on dark areas on crap offset paper the results have been good, provided there isnt too intricate screens to hold open

 

[tambo]

Thank you for the replies. I will try to add silver the next time. What do you recommend for the colors with say 80% trans. white? Do you put less trans white when adding silver or mix color as usual then add the 8% silver?