Application of water (fountain solution) into the press

[Deleted member 16349]

This is another potentially interesting area that I think could result in simplifying the operation of the process.

From my limited experience and from what I have read, the application of water is an operational problem. Problems with inking of some rollers in the dampening system that should not be inking up, toning on the plate even if there is sufficient water being applied, monitoring ph and conductivity, contaminated fountain solution that needs to be disposed of, setting rollers, etc. It seems to go on and on.

Normally water is added very near the plate. There are many systems that do this now but from various technical papers and existing products on the market, water can be added into the system at almost any point on the press and the process of separating the image area from the non image area on the plate still works fine.

There are already spray dampeners that are used on web presses and there have even been attempts to use single fluid inks that already have the water in it.

One very good reason to have the water application near the plate is because it is far from the ink fountain. If one applied water high up in the roller train, there is more chance that it will disturb the ink feed on conventional presses.

But let's think of a press that has positive ink feed which is not affected by the amount of water applied into the system and where it is applied. Since the amount of water applied will have basically no great impact on density control, the accuracy of water feed is not as critical and the location of application is not so critical.

When applying the water near the plate, the dampening system must apply an even water film in order not to introduce printing quality problems. But if the water is applied high up in the roller train, this requirement for an even water film is not critical because the water will be worked into the ink by the roller train.

The dampening system could be as simple as a drip system that provides a controlled drip of water across the press. It could be a "one way" water feed and not require recirculation. Without recirculation, it would only be necessary to ensure the right chemistry in the fount solution is provided. There would be no need for monitoring and maintaining a recirculation tank and no need to dispose of contaminated fount solution.

Even the chemistry of the fountain solution for such an application might be formulated to be more environmentally friendly.

I have not done this type of testing but I see a potential to reduce the cost of offset technology and simplify the operation.

Just a thought.

 

[RGPW17100]

One problem with adding water higher in the ink train is that water and ink repel one another( In the ideal world) This being the case you would not be able to transfer the ink to the rollers because they would be saturated with water.

 

[Deleted member 16349]

One problem with adding water higher in the ink train is that water and ink repel one another( In the ideal world) This being the case you would not be able to transfer the ink to the rollers because they would be saturated with water.

Ink and water repel, that is true but some water goes into the ink and is stable there. On press one always has emulsified water and ink. The process at the plate won't work if the water did not go into the ink. At least that is what I have read.

On press, water is driven into the ink due to the action of the nips to levels of emulsion that is unstable. Without the action of the nips, the water comes out of the unstable emulsion very quickly and wets the plate. At least this is how I understand it. Emulsification of inks and water is not my field.

Some press concepts ( Positive Feed Keyless concept from Goss) have run with the water added to the ink before it was feed into the press and it kind of worked. I don't think it is going to be a problem.

That is something to look for when it gets tested. If it gets tested. ;-)

 

[Green Printer]

This is another potentially interesting area that I think could result in simplifying the operation of the process.

From my limited experience and from what I have read, the application of water is an operational problem. Problems with inking of some rollers in the dampening system that should not be inking up, toning on the plate even if there is sufficient water being applied, monitoring ph and conductivity, contaminated fountain solution that needs to be disposed of, setting rollers, etc. It seems to go on and on.

Normally water is added very near the plate. There are many systems that do this now but from various technical papers and existing products on the market, water can be added into the system at almost any point on the press and the process of separating the image area from the non image area on the plate still works fine.

There are already spray dampeners that are used on web presses and there have even been attempts to use single fluid inks that already have the water in it.

One very good reason to have the water application near the plate is because it is far from the ink fountain. If one applied water high up in the roller train, there is more chance that it will disturb the ink feed on conventional presses.

But let's think of a press that has positive ink feed which is not affected by the amount of water applied into the system and where it is applied. Since the amount of water applied will have basically no great impact on density control, the accuracy of water feed is not as critical and the location of application is not so critical.

When applying the water near the plate, the dampening system must apply an even ink film in order not to introduce printing quality problems. But if the water is applied high up in the roller train, this requirement for an even water film is not critical because the water will be worked into the ink by the roller train.

The dampening system could be as simple as a drip system that provides a controlled drip of water across the press. It could be a "one way" water feed and not require recirculation. Without recirculation, it would only be necessary to ensure the right chemistry in the fount solution is provided. There would be no need for monitoring and maintaining a recirculation tank and no need to dispose of contaminated fount solution.

Even the chemistry of the fountain solution for such an application might be formulated to be more environmentally friendly.

I have not done this type of testing but I see a potential to reduce the cost of offset technology and simplify the operation.

Just a thought.

????????????
Stop.
There are 100's of fountain solutions available and only a few work with very little or no problems.
With the thousands of ink and fountain formulations it looks like that perfect combination has alluded many ink and fountain suppliers since offsets rise to predominant print production.
A properly made fountain solution and ink combination work synergenically and will only have troubles when there is a mechanical issue with the press. Only a couple of manufacturers have reached this milestone. Almost all printers who have achieved this keep their mouth shut.

If paper and substrates were perfectly clean with no service dirt and debris you would not have to recirculate and clean.
If the presses water trays could maintain an even 60ºF temperature circulation would not be required.
The environmental part has been done for close to 20 years.
There a very few that actually know this subject in and out.
I am not one.

 

[Al Ferrari]

"the dampening system must apply an even ink film in order not to introduce printing quality problems." (7th paragraph, first sentence).

Perhaps Erik meant to write "the dampening system must apply an even water film..."

Al

 

[Deleted member 16349]

"the dampening system must apply an even ink film in order not to introduce printing quality problems." (7th paragraph, first sentence).

Perhaps Erik meant to write "the dampening system must apply an even water film..."

Al

Thanks Al. I think I have ink films on the brain.

I made the change.

 

[HachiZenki]

You must not forget another variable in the equasion...namely the plate mfg. When we moved from cutting and pasting negs to CTP the plate mfg. recommended we switch from neutral solution to mild acid. We use Fuji plates and solution so I dunno if they made the recommendation just because the mildly acidic solution was more expensive or not. Oh yea and I've heard that one of the future techs is for 'waterless' presses where the ink is sprayed on not unlike an ink jet printer.

 

[Deleted member 16349]

You must not forget another variable in the equasion...namely the plate mfg. When we moved from cutting and pasting negs to CTP the plate mfg. recommended we switch from neutral solution to mild acid. We use Fuji plates and solution so I dunno if they made the recommendation just because the mildly acidic solution was more expensive or not. Oh yea and I've heard that one of the future techs is for 'waterless' presses where the ink is sprayed on not unlike an ink jet printer.

Not sure how the acidity would influence the concept but that is what a test is for.

On spray inking. I think an inkjet supplying ink is a possible concept and would be interesting to see.

I know of one research effort in spray inking that has been going on since 2002. This one is not waterless but does spray ink onto a test roller train.

The following is a link to the technical paper and presentation.

www.tu-chemnitz.de/mb/FAK/PrintMedienTech/pmforschung_en/pu_details_en.php?id=5656

Personally I don't think they have a chance of success the way they are going about this but that is for them to work out.

There are so many ways to do things and slight changes in approaches can make all the difference.

 

[inkinveins]

The role of the Dampening system is to apply water to the plate, prior to the ink form roller contact. To simply add foutain solution to the ink or roller train and hope for immediate emulsification, will not render the plate clean.

 

[Deleted member 16349]

The role of the Dampening system is to apply water to the plate, prior to the ink form roller contact. To simply add foutain solution to the ink or roller train and hope for immediate emulsification, will not render the plate clean.

Inkinveins, It has worked before on several occasions in the past and that is why I think it is still potentially a practical option. There are spray dampening systems on newspaper presses now that spray fountain solution into the roller train. So it is not such a far fetched idea.

I am still curious to see if it is workable.

 

[Al Ferrari]

With due respect, Inkinveins' view may be an old wife's tale. But it raises the question of wether the plate repels ink because it is wet, or because in the presence of ink and water, it prefers water. We have all(?) had the experience of dropping the ink rollers first on a dry plate on press, letting the plate ink up, and then dropping the water rollers to watch the plate clean up. So it is not so clear that the sequence is really that important.

Erik has for a very long time now been trying to make us realize that the inking system on lithographic press is a system in equilibrium. I would take that further to say that there are various equilibriums involved, and that the plate/rollers interface (for both ink and water rollers) involves just one of these equilibriums. (Thanks to Erik for that insight).

Al Ferrari

 

[Cornishpastythighs]

I have some limited experience with a Smith Pulsed Dampener, I found it very hard to control the ink/water, there were some nozzles that dripped and got plugged up the zone control didnt work well and it was overall a not very pleasant experience (maybe it wasn't a good example of the technology). I much preferred the Dahlgren type system.

 

[inkinveins]

Apparently all of the printing press manufacturers have it wrong, it is amazing to think how we are able to print at all with the predominant existing design.

 

[Al Ferrari]

"With due respect," was meant with all seriousness so that my comments would not come off as a personal affront to you and would challenge you to think about the substance that followed. Alas, that did not wok.

Al

 

[Deleted member 16349]

I have some limited experience with a Smith Pulsed Dampener, I found it very hard to control the ink/water, there were some nozzles that dripped and got plugged up the zone control didnt work well and it was overall a not very pleasant experience (maybe it wasn't a good example of the technology). I much preferred the Dahlgren type system.

Cornishpt. Yes, in your example it would be difficult to control because the ink was not being fed positively. I am also thinking in terms of a drip method as opposed to a spray method which clogs as you say. A dripping method which uses low pressure and larger orifices should help prevent the plugging problem.

The details of any design concept that makes all the difference. Trying to get rid of all those little devils in the details.

 

[Alois Senefelder]

Water !!

Water !!

Hello fellow Lithographers,

Some PDFs from "Deus ex Machina"