Ink and Water Balance Problems

[Brant]

We have a four color heat-set web press with brush roll dampening. For quite a while now, whenever we have lighter coverage in the center of the web, we have a problem balancing ink and water. If we turn the water down to keep the center area of the web from washing out, the edges of the plate dry up.
We use water stops to help in the center but even those are sometimes not enough. Our rollers settings are correct, the fountain solution is at the manufacturers recommended dosage. Conductivity, pH, and temperature all in check. Press audits reveal no abnormal temperatures. There have been no changes in any consumables.
The only suggestion we have had so far is an air bar system.
Does anyone else out there have some ideas we can try or things we can look at?

 

[veejay18]

Try useing IPA at 3-5 % it will reduce the surface tension of the fount so that you will get uniform & fine water film across the plate.

 

[Brant]

Thanks for the information.

 

[pa printer]

Sounds like a roller out of round, it does not take much. If you are flooding the centre but drying on ends something has to be out of scew, like on the heidelbergs. The air bar would help alot and you could rig one up quickly. But something else is going on here, just do not know what.

 

[Brant]

Re;pa post

Thank you for your feedback. I will look into this matter further.

 

[Penguin1100]

hook up a airhose and regulator till the job is done..... isnt printing fun

 

[sakthihariharan]

I thing u can water controller blade at the edges with minimum water flow from pan roller to brush rool.

 

[Maria2009]

I do agree with you. Those are the most effective way

keyword

 

[tonygreg]

You are right buddy.

Sounds like a roller out of round, it does not take much. If you are flooding the centre but drying on ends something has to be out of scew, like on the heidelbergs. The air bar would help alot and you could rig one up quickly. But something else is going on here, just do not know what.

 

[printing.hari]

can u please explain the problem u r facing in the print clearly?
i cant get u.

 

[nosefo]

Your pool roller needs to be changed. This is probably shaped like a "banana" increast diameter after years in service. The increased diameter in each end of the roller let less water pass your system on the edge of the printing form. You then have to run with a higher value of water to keep the plate clean near the edges, with the result that you have to much water in the middle of the form.

Tip: When changing/ordering new pool rollers ask your supplier if he can add a sealing "silicone" at the edges of this roller. This will prevent dampenig solution to penetrate the roller, and the roller will last for a longer period.

 

[graphix emporium]

Sounds like a roller out of round, it does not take much. If you are flooding the centre but drying on ends something has to be out of scew, like on the heidelbergs. The air bar would help alot and you could rig one up quickly. But something else is going on here, just do not know what.

agreed, your rollers are out around, check your stripes and anything that's under half in the center than whats on the sides and its stuffed. if ones obviously worse than the others then adjust it off and try a print, you can usually get by with out it till you get it reground or swapped over

 

[bikozak1]

I would be interested to know if you use anything to remove the ink where there is no coverage, eg. color bars. They can help remove water-logged ink. I would be interested to get an idea as well of your ink and water balance window. Try this printing tip.
Also, it sounds like you've done your homework on the water, but why not try another ink. A competitor would be probably more than happy to give you a sample.
I might add, I worked with brush dampening for about 4 years and also ran into this problem. We controlled it with water stops and had to ensure they were tight up against one another and stripped the water well.

 

[Brant]

Thank you for your feedback. Rollers are usually checked and changed on a regular basis but I will have the Pressman check again.

 

[Brant]

bikozak1, yes we use color bars to remove excess ink. Water window is only good for about 3 or 4 hits one way or the other when this issue occurs. We also use water stops on a regular basis. Changing/trying another ink company's' ink for us is not an option at this time. Thank you for your tips and feedback. I will review these items with Press Operators.

 

[jonprintz]

Does anyone else out there have some ideas we can try or things we can look at?

The best fix is to make sure that all of your rollers are back in factory original specifications. If you cannot make that happen or if you are still fighting the issue after doing so, try some variation of what is outlined below and see how it works out.

When you have an upcoming job with light coverage have your operator clean the ends of the brush roll real well but not the center of the brush.....or, if you have an extra set of brush rollers, keep a brush roller or two on the shelf intentionally left dirty in the center but not on the ends to put in when you have a light coverage job in the center of the web. You will still need to run the water drags.

During my days on the press we used a horsehair type brush and hand cleaner to clean the water brushes.

Good luck with this.

 

[James Pressman]

This is a shortcoming of brush dampening. I use the same and all you can do is run your waters as low as possible and put as many water stops down as possible. It's not easy and your ink and water balance window definitely narrows.
Try comparing your ink and water balance window with low coverage and without. Sometimes it's just an educational process of how to deal with it.
You can also try printing as much coverage as possible in areas that are trimmed (say at the color bars).

 

[lowerhydro]

ALL brush dampners have the same issues, somewhere across the sheet. We fought this problem for over a year, checking every roller to make sure everything was 'to spec'. The way we solved this problem was to 'map' each unit for wet/dry areas. Then INCREASE space between the spirals in the 'wet' areas (reducing water flow) and DECREASE space between the spirals in the 'dry' areas (increasing water flow). Once we corrected the whole press, running it was a pleasure. The machine was working for US, not us working for the machine. Try it, you'll like it.

 

[Even2011]

Thanks for infomation Ink and Water Balance.

 

[Uimeas]

Hope it goes well for you!