UV offset production

[Green Printer]

I am looking into UV offset prodcution. What are the pro's and cons?

 

[kansasquaker]

Well one of the cons is that you'd be in the printing business. But other than that UV is fine. It's a lot more work, more headaches and new and more expensive consumables. But there are things you can do with UV that you simply cannot do conventionally. If you have a piece of business on the line that justifies it, it's probably worth the effort. If you're considering it on the come, think very hard. It's a substantial investment of time, money and angst.

 

[arossetti]

Can't use processless plates.

 

[Devil Dog Dan]

You can use no bake plates and UV is well worth the investment if you have the need. Just takes good Pressman to run it and dont listen to all the it's a really complicated process. It's really not. Been doing it since the late 80's. Good Luck

 

[vaithi47]

hi can anybody help me please! when we do uv printing on met pet with tape pull test the ink is coming off when i check the surface tension of the met pet i am getting around 38 to 42 dynes /cm

 

[aqazi81]

A bit of Copy/Paste work from a pdf.


Adhesion of UV inks
In the past, UV inks showed restricted adhesion on foils and
films, but these issues have beenovercome by newly developed special ingredients and optimized ink
formulas.
An essential condition is, however, that the substrate such as PVC
does not contain any plasticizers, static inhibitors and other substances that might diminish adhesion.
The recommended surface tension for PVC is 35 mN/m. For substrates made of ABS, PP, PET, PE
and PS, a surface tension of over 40 mN/m is essential.
These substrates as well should be free of problematic additives like static inhibitors, which might impede
uniform ink adhesion due to their separating effects.
The correct surface tension in a synthetic substrate lies in the material formulation and thus with the manufacturer of the substrate. Manufacturers also sometimes use so-called corona discharge technology to electrically treat the surface of films. The surface tension might fall during longer storage of the substrate, and the corona pre-treatment must be repeated directly in the web or sheet-fed press.
This option is also advisable if non pre treated substrates are used for economical reasons.
Moreover, the molecular structure of the cured ink layer widely influences adhesive characteristics,
flexibility and scratch resistance.

 

[Green Printer]

Looking further into UV I have found that there are many restrictions and conflicting reports with UV in relation to pharmaceutical, cosmetic and food packaging? Another concern are misting UV inks dangerous to the press crews?

 

[Pressroom Specialist]

UV printing has come a long way. Yes, In some cases the ink will cause an allergic reaction on soft skin. You need to be a clean pressman Slobs will get the ink everywhere and it will not dry. The running window is smaller and I can only stress there are no shortcuts. With correct rollers you can run both UV,HUV and conventional ink. NBR rollers will need to be changed before running any uV. Some UV inks have a very strong odor that is offensive to people in the food industry. Good quality inks have been developed to fix these problems. Always available to discuss further.

 

[DeltaE]

UV printing has come a long way. Yes, In some cases the ink will cause an allergic reaction on soft skin. You need to be a clean pressman Slobs will get the ink everywhere and it will not dry. The running window is smaller and I can only stress there are no shortcuts. With correct rollers you can run both UV,HUV and conventional ink. NBR rollers will need to be changed before running any uV. Some UV inks have a very strong odor that is offensive to people in the food industry. Good quality inks have been developed to fix these problems. Always available to discuss further.

Pressroom Specialist Could you pls sharez your experience on UV printing on PET?
You had mentioned the smallet running window. If I right understood, it coule be esier to get scumming or over-elmusification when printed on PET, isnt it?

 

[engin]

Looking further into UV I have found that there are many restrictions and conflicting reports with UV in relation to pharmaceutical, cosmetic and food packaging? Another concern are misting UV inks dangerous to the press crews?

There are food grade LMQ UV inks available in the markets, but due to recent REACH regulations in EU, the photoinitiators are been investigated and sone PI's will be out of use which results in poor adhesions and drying.
or misting of UV inks, a suitable fount solution search will help and reduce the misting, some founts will tend UV inks mist too much while some will reduce reasonably.

 

[Green Printer]

There are food grade LMQ UV inks available in the markets, but due to recent REACH regulations in EU, the photoinitiators are been investigated and sone PI's will be out of use which results in poor adhesions and drying.
or misting of UV inks, a suitable fount solution search will help and reduce the misting, some founts will tend UV inks mist too much while some will reduce reasonably.

Engin what is the relationship between fountain solutions and the misting?

 

[engin]

Engin what is the relationship between fountain solutions and the misting?

Before the ink transferred from plate to blanket,on the plate it absorbs some amount water ( 15-20 % may be) in it called as emulsification, without absorbing the desired amount of water ink does not transfer from plate to the paper
(In winter or cold environments since the viscosity or the body of the ink is so tough and can not absorb the water inside on the plate, you can see the ink level is ver low on the paper. Then what you do either you heat the ink before putting into the duct or add some reducer to weaken the body or reduce the viscosity then the ink tends to absorb water and starts to transfer on to the paper and reaches maximum level when the ink-water balance achieved).

If the ink absorbs more than desired amount ( called as over-emulsification) than tend to not transfer and in this case the press operator tries to increase the ink level on the paper and opens the inks on the control panel but can not. Since the ink is overemulsified then it is not transferred as desired so the excess amount of the ink tend to mist around by centrifugal forces while the rollers turn.

The better fount solution choice will make ink establish the ink-water balace very quickly at the desired emulsification rate resulting in better ink transfer with minimum ink layer on the plate and blanket. As a result minimum level of misting.

Here, the fount solution establishes ink-water balance at desired level which is the key point for offset printing.

 

[engin]

Before the ink transferred from plate to blanket,on the plate it absorbs some amount water ( 15-20 % may be) in it called as emulsification, without absorbing the desired amount of water ink does not transfer from plate to the paper
(In winter or cold environments since the viscosity or the body of the ink is so tough and can not absorb the water inside on the plate, you can see the ink level is ver low on the paper. Then what you do either you heat the ink before putting into the duct or add some reducer to weaken the body or reduce the viscosity then the ink tends to absorb water and starts to transfer on to the paper and reaches maximum level when the ink-water balance achieved).

If the ink absorbs more than desired amount ( called as over-emulsification) than tend to not transfer and in this case the press operator tries to increase the ink level on the paper and opens the inks on the control panel but can not. Since the ink is overemulsified then it is not transferred as desired so the excess amount of the ink tend to mist around by centrifugal forces while the rollers turn.

The better fount solution choice will make ink establish the ink-water balace very quickly at the desired emulsification rate resulting in better ink transfer with minimum ink layer on the plate and blanket. As a result minimum level of misting.

Here, the fount solution establishes ink-water balance at desired level which is the key point for offset printing.

In winter, while visiting a newspaper where the logo design was solid cyan and 40 % magenta dots. The cyan was not transferring on to the paper and picking the paper surface and the operators were trying to increase the cyan level from control panel. Around 50000 copies after the press got heated up then cyan reached ink-water balance then the logo becomes darker and darker ( since cyan started to transfer) then the operators were trying to reduce the cyan level that they increased previously.
When the temperature of the press increased then the viscosity of the cyan decreased and started to absorb water. When ink-water balance achieved then maximum ink transfer resulting in smooth solids and darker and darker shades.
So, the key point is that in cold environments, before start of the print, very low amount of reducer should be added into the ink since as the print run goes, the press will be heated up and if the operator still adds reducer, then the viscosity of the ink drops and results in over-emulsification.

 

[Deleted member 16349]

Before the ink transferred from plate to blanket,on the plate it absorbs some amount water ( 15-20 % may be) in it called as emulsification, without absorbing the desired amount of water ink does not transfer from plate to the paper
(In winter or cold environments since the viscosity or the body of the ink is so tough and can not absorb the water inside on the plate, you can see the ink level is ver low on the paper. Then what you do either you heat the ink before putting into the duct or add some reducer to weaken the body or reduce the viscosity then the ink tends to absorb water and starts to transfer on to the paper and reaches maximum level when the ink-water balance achieved).

If the ink absorbs more than desired amount ( called as over-emulsification) than tend to not transfer and in this case the press operator tries to increase the ink level on the paper and opens the inks on the control panel but can not. Since the ink is overemulsified then it is not transferred as desired so the excess amount of the ink tend to mist around by centrifugal forces while the rollers turn.

The better fount solution choice will make ink establish the ink-water balace very quickly at the desired emulsification rate resulting in better ink transfer with minimum ink layer on the plate and blanket. As a result minimum level of misting.

Here, the fount solution establishes ink-water balance at desired level which is the key point for offset printing.

IMO this explanation, even though it is often used, is quite faulty.

IMO, the amount of ink transfer basically has nothing to do with ink temperature, ink viscosity, roller pressures, water, press speed, environmental conditions, etc. The amount of ink transfer to the paper is only related to the amount of ink fed into the press on average. This is irrespective of how the ink is fed into the roller train.

This has been tested and anyone can test it and they will get the same results. This is about the quantity of ink and not the quality of that print. It is funny that ink companies don't seem to care about this but continue to push the myths.

But of course there is a lot of resistance to thinking in this way. For those who think that somehow changes in water or temperature affects ink transfer to the paper, I would ask a question and it would be interesting to hear their explanations.

So if you think the adjustment of the ink feed is consistent on an offset press but the printed ink goes down to a lower level when increasing water, where did that missing ink go? Does it just disappear?

 

[Alois Senefelder]

Hello Erik,


Here we go again with your - Wrong Information regarding Offset Lithographic Printing,

SO HOW DO WE PRINT - with just "INK" ????????????


Regards, Alois

 

[engin]

Some pdf's

 

[Green Printer]

Engin

Using the same ink why do some fountain solution mist and changing to a different fountain solution ink misting is virtuall gone. Do some fountains solution break down ink?

 

[engin]

Engin

Using the same ink why do some fountain solution mist and changing to a different fountain solution ink misting is virtuall gone. Do some fountains solution break down ink?

Actually the formula selection of the founts by the chemist will help in such problems, actually I do not know the phenomenon but just ask to the formulator and he gives only the product name nothing more, but the suggested founts works better than normal one.

At a printing house, we've seen a strange misting for UV inks on the press like a flying cloud. The same ink and just changed to a different fount then the cloudy misting has gone.
There are different types of founts even for the same supplier. Some founts are formulated for general purpose and some founts are chosen and specially formulated for different kind of observed chronic problems on the press like reduction of roller glazing.

Some specially designed for some press configurations only ( seen a heat set fount designed with the same given name of the press, for Goss sunday M4000 press, for example ) in this case the formulator makes some tests for chosen founts and revise the formula and optimise until the operator satisfied.
Therefore,sometimes using a general purpose fount may not work efficiently for some presses and in this case ( from the suppliers) should be asked if any specifically formulated founts are present or not? or trial and error procedure?

UV ink run on the press is normally harder than conventional inks.

Therefore the best coice in my opinion, is to call the supplier, show or define the problem and get a suggested fount option from him.

 

[HRoss]

Actually the formula selection of the founts by the chemist will help in such problems, actually I do not know the phenomenon but just ask to the formulator and he gives only the product name nothing more, but the suggested founts works better than normal one.

At a printing house, we've seen a strange misting for UV inks on the press like a flying cloud. The same ink and just changed to a different fount then the cloudy misting has gone.
There are different types of founts even for the same supplier. Some founts are formulated for general purpose and some founts are chosen and specially formulated for different kind of observed chronic problems on the press like reduction of roller glazing.

Some specially designed for some press configurations only ( seen a heat set fount designed with the same given name of the press, for Goss sunday M4000 press, for example ) in this case the formulator makes some tests for chosen founts and revise the formula and optimise until the operator satisfied.
Therefore,sometimes using a general purpose fount may not work efficiently for some presses and in this case ( from the suppliers) should be asked if any specifically formulated founts are present or not? or trial and error procedure?

UV ink run on the press is normally harder than conventional inks.

Therefore the best coice in my opinion, is to call the supplier, show or define the problem and get a suggested fount option from him.

The use of UV inks in Offset printing goes back to the '70's. All the issues mentioned existed and have been addressed. There are numerous highly capable ink companies that will easily walk you through the setup and running of a UV ink. As to food packaging, medical supplies, etc., these have also been addressed and the information about some of the challenges in the future are describes ay www.radtech.org This is the industry organization focused on UV and EB curing. Review their Printing and Packaging sections.

 

[robb]

"So if you think the adjustment of the ink feed is consistent on an offset press but the printed ink goes down to a lower level when increasing water, where did that missing ink go? Does it just disappear?" Eric

Eric, you tell me --because I know, as any pressman who pays attention does, that you can increase the density of the ink on the paper by backing off the water-it is a method to make sure water is at a minimun. When I am running along and everything is settled down, I can increase the water 20%, and densities on all 4 colors will decrease 10-20 points-turn water back down, and densities will quickly go back to where they were. It is not a question of "missing ink" it is a fact of "watered down" ink.
Whaddya think?