problem with carbonization

[Alex Arriaza]

hi everyone, im having a problem on a job using a komori 640, we are using hostmann Resista inks, and the paper is a bond 80 and 7.5 - 8 PH, fountain solution 1398us - 1645us, fountain solution PH 4.4. We made the run at the end of the day like about 7Pm, and left the material to dry, at the next day we did the side-back and apparently the ink is going off on the impression cylinders, so on the front-side it appears this scratches on the impression like white pitting, any ideas?

 

[RGPW17100]

Sounds like the ink is picking off the sheet. Try reducing the squeeze and use a good cylinder cleaner desensitizer. Paper seems to alkaline and may be attacking the driers in the ink. Maybe next time try adding a three way drier to the ink and see if that improves it.

 

[Happyprinter]

Ink Picking

Ink Picking

We have had the same issue with our Komori occassionally, especially when we are running any type of blue ink.. Our solution has been to reduce pressure, watch ink control closely, allow plenty of dry time and keep that back cylinder spotless.

 

[madjock]

If you have chromed impression clyinders, polish them good and proper with Autosol chrome cleaner and they will stay as clean as a whistle.

 

[GazKL440]

Try running hostmann impression series rather than resista, its far better IMHO. Follow the rules...minimum ink, minimum water and minimum impression... and when running on bond, break up the run into shorter runs and try to back it up asap, especially with hostmann ink (been using it for years and have a pretty good feel for it).

hope this helps..

 

[Bob Peterson]

Almost all papers manufacured today are alkaline. Alkline papers will not slow down the ink oxidation process. Most likely the problem is due to a non-skinning ink and/or excessive fountain solution run on the 1st side.

Is the Hostmann Resista ink you are running a stay-open / non-skinning ink? If so, most likely that is the cause of the problem. Stay open inks tend to exhibit just this problem on uncoated / bond stocks. This is due to the anti-skinning agent in the ink formula.

If the Hostmann Resista ink is a skinning ink, I would suggest that you only run enough fountain solution to keep the non-image area clean.

 

[Inks]

Bob Peterson is correct. The Hostmann Resista however, is a hard dry type ink that sets slow, but is designed to dry on hard to cure substrates. I am sure they have faster setting lines to offer, if the issue is the ink.

 

[Alex Arriaza]

i did another couple of tests, test 1: this time i used Rapida from hostmann, and let the front side cure the hole night (the same as before with rapida), and did the back side at the next day, i had the same results as before..... test 2: this time i use resista and did the run in small batches from 5K to 8K so i did the whole front and back side in the same batch with out waiting for the ink to cure and the problem disappeared.

So im guessing the problem its when i left the ink to dry, this shouldnt sound like a big deal doing small batches but im having this big job 300K and dosnt use the same plates on the side front and back so im really worried because the ink doesnt work

 

[JOHNYPRINT]

hHi alex arriaza
We run a lot of this type of paper and all the calcium carbonates in the paper that they use to bulk the paper out with gets into the fount solution and makes it very alkaline. check that your conductivity is'nt too high, check the Ph level in the tank and the trays. How frequently does the tank get cleaned and the trays get cleaned out, they can accumulate a sludge in the bottom of them.
hope this helps along with the other ideas. regards johnyprint

 

[Alex Arriaza]

we prepare new fountain solution every two days, the parameters i described first are the ones that weve been using should i go with lower parameters_??

 

[Bob Peterson]

i did another couple of tests, test 1: this time i used Rapida from hostmann, and let the front side cure the hole night (the same as before with rapida), and did the back side at the next day, i had the same results as before..... test 2: this time i use resista and did the run in small batches from 5K to 8K so i did the whole front and back side in the same batch with out waiting for the ink to cure and the problem disappeared

If i'm understanding you correctly, when you did test #2 you printed the first side and then immediately turned the job and printed the back? If this is true please see my questions below:

1. How long did it take for you to run the first side before you printed the back?

2. By any chance did you happen to notice if the ink on the first side of the sheet was still wet? or did it appear to be set?

The reason for my questions above are if the ink remains open i.e. (wet to touch), not tacky, it will not build up on the back cylinder. As I had indicated on my previous post, inks that stay open take longer to dry on uncoated stocks. If allowed to sit overnight before backing up, they will only tack up at best. Therefore, causing the ink to build up on the backcylinder due to the surface of the ink film being tacky and the underneath still in the oxidation stage.

So im guessing the problem its when i left the ink to dry, this shouldnt sound like a big deal doing small batches but im having this big job 300K and dosnt use the same plates on the side front and back so im really worried because the ink doesnt work

I completely agree with your above quote. Obviously you are running a large job and do not have the capacity to perfect or immeadiately print the backside. Using your current inks will prove the same problem as before.

Speak with your ink supplier and communicate this concern with them. If they are unable to provide you with a product designed for the application, I would seek out a different supplier who is responsive to your needs.

Best of luck!

 

[Alex Arriaza]

Yep thats exactly the problem, what kind of ink would you recommend, the ink dealer only has rapida and resista on stock, so ill find some else, but i also would like to know were can i find more info about ink properties, because the info i have apparently is wrong.... of course the dealer gave that to us, so please if you have any more info on inks ill appreciate some links.

ill print a stock on the same paper today, ill wait mor time for the ink to dry like 3 days or so, and ill do the test again and post the results, do you think this would help_?

 

[Bob Peterson]

Yep thats exactly the problem, what kind of ink would you recommend, the ink dealer only has rapida and resista on stock, so ill find some else, but i also would like to know were can i find more info about ink properties, because the info i have apparently is wrong.... of course the dealer gave that to us, so please if you have any more info on inks ill appreciate some links.

ill print a stock on the same paper today, ill wait mor time for the ink to dry like 3 days or so, and ill do the test again and post the results, do you think this would help_?

Alex,

It would be wrong of me to recommend an ink supplier as I work for an ink manufacturer. With that being said, If your ink dealer is unable to help you I would contact the closest ink manufacturing company in your region. Explain the problem to them and they Should be able to provide you with a product.

If you would like to speak with me directly drop me a PM with your number and I will give you a call.

Regards

 

[Alex Arriaza]

i just discovered something, 1st. we are using a fountain solution with 30% of glycol and our ink is a stay-open/non skinning ink, and apparently this chem reaction affect the way the open ink dries, so should i change the fountain solution__?

 

[Bob Peterson]

Alex,

Regarding the fountain solution. My personal preference is a 2-step using 3-3.5 oz of etch and 1-1.5 oz alcohol substitue per gallon of water. With that being said, you should be able to safely use a 1-step solution up to 5-ounces per gallon.

The glycol in the alcohol substitute will slow down the ink oxidation dosed too heavily, and especially if too much water is run on the job with a light coverage form.

Regards

 

[Alex Arriaza]

the ink supplier came today and i showed him the issue, i told him about the property of the ink the non-skinning/stay-open, he said that its not recommended to use dry ink because it builds up on the rollers, at aprox. 20K sheets is this true??? ive never used any different ink than the one we are currently using, so ive never seen a dry ink working on a press before, so his bright idea to solve the problem was to put driers on the ink as well on the fountain solution, i think this will not reduce our problem but ill make it worse because as far as i know drier affect only the way oxidation reaction occurs on the ink, so the tack sill remain the same on the paper and it will fall off the paper as it is right now, am i right?

Thanks

 

[Bob Peterson]

Alex,

Your supplier's comment regarding the ink building up on the rollers after 20K sheets is not correct. Ink building up in the rollers on the press has nothing to do with whether or not an ink is designed not to skin.

Adding extra drier to the ink and a fountain drying stimulator will help speed up the oxidation process. However, with that being said, non-skinning inks will still take longer to fully oxidize on a uncoated substrate.

 

[Alex Arriaza]

the test we performed yesterday did work the problem remained the same, but i noticed some thing interesting, the pilling its not constant in every sheet is doing it alternating the problem 1sheet bad, 1 sheet good, i believe its because the cylinder grabs two sheets so.... the cylinder should have some thing to do with the problem, i mean of course the ink is not suited for the job but an imperfection on the cylinder should catalyze the problem, at least thats what ive observed ill put more info as soon as i start printing the back with the cleaning procedures.

 

[nhprinter]

My Two Cents

My Two Cents

Hi Alex,

What you're experiencing is not uncommon. The ink is simply pulling off on the back cylinders (impression cylinders). It's not always going to pull off at the same rate so each of your cylinders will look different. (I'm assuming from what you said you have double impression cylinders)

Before the advances in inks and the common use of IR driers it use to happen all the time. Most shops around my area always had either a good car wax or an industry product for waxing the impression cylinders that would slow down the process, but there was never a really good fix.

Nowadays it's the high alkaline sheet the day after running just as you've described. If you back it up the same day it hasn't had time to partially dry and build up tack so it runs fine. I've run into this a few times. We use to run a C1S cover that we HAD to make sure we ran the coated side first or both sides the same day or we were screwed.

Here are a couple of suggestions:

If running a different ink is not an option....you can wipe your impression cylinder's down with a good silcone. (NOT an spray can, but a liquid) Prisco makes one called SLIDE that will slow down the piling quite a bit. Squirt it on a rag and apply a heavy dose to your cylinders. (don't get any on the floor or someone will get killed....it's THAT slippery)

Another suggestion would be to add some Overprint varnish with Teflon to your ink. We use Superior's CV-911. I would think it would help it dry a little harder and will take some of the tack out of the ink which may be just enough for you to get through the job.

Also......I've never tried it, but I would think that adding wax to the ink may also help. Bob Peterson may be able to shed some light on that. I use to add wax to our Reflex blue to make it more scratch resistant on certain stocks so I know you can get it.

Hope this helps. Good Luck.

Dave

 

[GJOHN]

Some inks pick up too much water, depending on the resins used in the varnishes that make up the inks. There are Carboxyl and Hydroxyl groups on the resin structure and the Hydroxyl (OH group) loves water. So when the ink film has too much glycol ethers and other slow solvents picked up from the fount, it is will not dry thorougly. There is a point of diminishing return for any additives used like extra driers or wax compounds in an ink system. I would ask the ink supplier if this is a new ink system (the INKREDIBLE series).
Hope this helps.