drying problem. still.

[spigot]

Ok, i have this problem. When printing books and catalogues that require pressing, no matter how long i let the ink dry for, it almost always sets off, sticks together in the folded sections. Only way seems to be varnishing the 4 color secions.
When i deliver the sheets to bindery, there is no set off, and they feel dry to touch. Ink keys into stock fine, and has a nice gloss.

To fix this i have changed to a "quick set" 4 colour set ( a big pain due to not being duct stable ), gone over chemistry and it is within the window, PH around 5.The press has a alcohol chiller system and conventional dampers (i think this is strange) and i run around 3% alcohol. They only have 1 forme damper per unit as well. no one can explain where the other ones are!
The stock is normally good, and the printroom has a fairly stable environment, normally 22 degrees 6am 6 pm, decreasing overnight.
I also run all my colours slightly lower that standard, although balanced. Instead of 1.3 i would run 1.15 - 1.2 for example.
I also use a very healthy amount of powder, as i have no assisted drying.

I have the boss bleating on about having to seal things now, and im sick of talking to him.

Can anyone offer any suggestions about improving this situation?

cheers

 

[GazKL440]

what fount are you using does it include driers?

seems strange that feels fine till bindery get it mayhap we can blame them??

a liitle more alc may help dry in too, but watch balance...one forme wont hurt we ran single formes on conventional aki's all the time cos the bottom one was a BASTARD to get in and out.. the harder drying ink should help but duct cleaning will be a punish...

seems to me you are doin everything right maybe talk to ink supplier if anyone else has similar issues or if another fount is available that may help harden it up some...as chopper would say

 

[gordo]

Just a thought...

Because you are running your SIDs very low compared with industry norms ("Instead of 1.3 i would run 1.15 - 1.2") and likely the film thickness the inks were designed to run to, perhaps your fountain solution (a solvent) and the alcohol (a solvent) is breaking down the resin (which acts as a binder to affix the ink to the paper) in the ink. The ink would dry but doesn't stick to the substrate. ("When i deliver the sheets to bindery, there is no set off, and they feel dry to touch.")

best, gordon p

my print blog here: Quality In Print current topic: The creative/production process - redux

 

[Al Ferrari]

Do an off press ink on paper test. Do a draw down and/or apply ink to paper with a small roller brayer approximating the printed ink density of 1.15 AND 1.3 (do both). Let this sit overnight and then test under heavy cutter clamp pressure with clean paper on top.

The object here is to test the ink/paper interaction without the influence of the fountain chemistry. Make enough test samples that you can test after 12, 24, 36, and 48 hours. Post back results, as well as making them available to your ink supplier.

Al

 

[D Ink Man]

A quick set ink may be just the opposite way you want to proceed. I would check and see the amount of VOC's you are averaging in your four colour series. Traditional quick set inks can have as much as 10-15% of petroleum solvent by total content. The purpose of this solvent is to provide capillary action into the paper substrate, the mechanism for 'quick set'. If you did not have issue on press while printing with offsetting or blocking type of problems, I would consider going to a higher solids type ink, one with more vegetable oil versus petroleum distillates. The result will be a harder ink film formation and less tendency for sticking in post press procedures in the folding, binding operations. This is all predicated if you give the ink enough time to go through all 3 necessary phases; setting, drying and polymerization. If you need an excellent ink to help you accomplish this a recommendation can be made. Good Skill.

 

[dimitri]

"Only way seems to be varnishing the 4 color sections."
Have you tried decreasing the TAC as well? It could be an easy fix if whatever happens happens only on the rich blacks, or it could at least help together with the other suggestions made in this post.

 

[Johnston Collins]

i think you need to check the pH of the paper, if it is too acidic , this will increase drying time to more than 60 hours!
ink must be matched to paper type

 

[Johnston Collins]

i think you need to check the pH of the paper, if it is too acidic , this will increase drying time to more than 60 hours!
ink must be matched to paper type

sometimes too much dryers can also have the opposite effect
are you using IR/hot air dryers?

 

[spigot]

hi guys

Ok to answer some questions put forward.
No assisted drying whatsoever. Not even Grafo or Cobalt addition.
I have done some tests with different inks and it appears some are better than others, so i may have to look at changing.
The worst problem i had was with hostmann steinberg resista and hostmann steinberg foutn solution (the green liquid) with 5% alcohol. It just stuck fast togehter in the bindery.
Since then, i have changed to quick set ink and a different fount, which had noticeable improvement.
I think the comment on TAC is correct, in areas of high coverage, for example a forest at dusk with alot of cyan and black shadow areas it is more likely to have this problem.
Also tried rolling stripes onto paper, and it appears to have dried fine.

I cant always say to the bindery "I delivered the sheets dry what the hell did you guys do??" haha
So that leaves the problem being.... TAC and fount???
My fount acidity is around 4.8 mostly, with the recommended conductivity from the manufacturer, and it is renewed frequently due to usage.

It also is terrible on matt stocks but thats to be expected i guess.
Thanks to anyone who may have an idea!!

 

[GazKL440]

Is your fount solution called "solar fount", sort of dark green? We run that fount with hostmann steinberg "impression" series ink and have had problems with drying on certain stocks(matte, but only one brand of paper) and one issue with a job that was cut, folded then sent away to be inserted into newspapers and pallet loads turned up like bricks, this was traced back to TAC with very heavy screens in CMY behind solid blacks. We run without assisted drying as you do but about 10%alc and god knows what PH level and aside from the issues i have noted have no real problems... is BJ your hostmann rep?

 

[D Ink Man]

Ok, try Braden Sutphin Earth Pride Process Series. As previously mentioned, you need a high solids ink that dries hard with little VOC's to overcome the problem. Go to Braden Sutphin Ink Company for technical information and contact information to order. Phone 800.289.6872. You'll thank me someday.

 

[sivabalan]

Drying

Drying

Try to stop using Alcohol , just use your current acidic Fountain at 2-2.5 %. or you can add special driyer into your dampening solution. Without using IPA it can help the ink dry faster and keep your dampening temp at 10 - 14 C .

 

[Print Guru]

Hi,
I agree with gordo – printing lower densities can lead to drying problem.
More over, by using only 1 dampener you transfer more water to the plate (and more to the gripper edge than with 2 rollers) and this increases the emulsification of the ink which leads to drying problems.
I wonder about your print run? Please check the problem with sheets at run start and run end if the problem is the same.
Powder: this is the big joker as u said: "I also use a very healthy amount of powder, as i have no assisted drying. ". Some time the powder is the one that creates the problem – not the ink and u said "When i deliver the sheets to bindery, there is no set off, and they feel dry to touch. Ink keys into stock fine, and has a nice gloss."
What I did once is to remove the powder from couple hundred of sheets both sides and monitored by my self the folding/ bindery process. I found that it was the powder to make all the trouble. Make a test: run without powder 200-300 sheets and take out separately to dry then mark the sheets and send them to the bindery and see what happens.
Just a thought: If the powder u use is the sugar based one then may be humidity changes from your print room-delivery-bindery causes the powder to stick.
To summarize: 1 dampener, more water, less drying, heavy powder – a recipe
for problems.
Keep ph 5+ as going lower is more acid and inhibit drying.
I hope I could help

 

[Beergod]

I second the notion to check the surface PH of the paper. If the surface is slightly acidic it can neutralize the driers in the inks. Even a sheet that has a lot of "calcium in the coating" can be slightly acidic. Alkalinity can fade over time and this can be accelerated depending on the conditions that the paper is kept in. Scrapbooking places sell pens that can tell you if a paper surface is acidic or alkaline. If you need to quantify the measurement, TAPPI has a procedure for measuring the surface PH of paper. I believe its T 529 if memory serves. Good Luck.

 

[BusterE]

BusterE

BusterE

All of these answers are right and playing some part in your problem.To fix the blocking have your Ink co. add teflon wax and a small amount of silicone or a stock Ink with it in the formula.

Good Luck,

 

[Ink Tech]

If this is an issue that you get on every print job rather than special jobs (uncoated/plastics etc), i'd recommend a harder drying or laser ink set coupled with a hard drying sealer. It'd be the quickest way to get jobs through the press.

 

[Albert Noel]

of all else fails, and if you are partial to the hostmann inks, try the INKredible Rapida series cmyk inks.
stays duct fresh (we leave ours in the fountains for the whole week, with only minor drying by friday, nothing a little anti-skin spray wont fix) and they set pretty fast and within 15mins (usually less, depends on coverage) they can be backed up and within an hour or two, they are pretty dry and ready for bindery.

i would also move away from the hostmann fount. try something from unigraph or perhaps prisco. some of them have driers added to them. i would also stay away from any that have glycol as it will slow drying.

you can also try a product called Speedy Dry. it's an additive you can add to the ink. it works VERY well if used right.

 

[D Ink Man]

Not Quick Set, again this is the opposite of what you need. You need a "HIGH SOLIDS INK". Tell your ink guy to put 3% of ********* *** and 2% **** into the formulation.. VOC levels should be no more than **%. That will fix your post press problem. No doubt about it!