D
Deleted member 16349
Guest
Al and Cornish,
I hope you are starting to realize that you are are starting to understand this part of the process better than Heidelberg or the other press manufacturers and experts. Kind of scary.
Al and Cornish,
I hope you are starting to realize that you are are starting to understand this part of the process better than Heidelberg or the other press manufacturers and experts. Kind of scary.
fiatlux
Well-known member
Of course not. As Harvey Levenson so clearly stated. The ITB "just does not make sense" and "the concept of the invention is too complicated for existing press configurations and it is really not marketable." I assume because printers are not interested any technology that may provide more consistent presswork.
To which I'll add:
"There is no reason anyone would want a computer in their home."

- Ken Olson, president, chairman and founder of DEC
"But what...is it good for?"
- Engineer at the Advanced Computing Systems Division of IBM, 1968, commenting on the microchip
"So we went to Atari and said, 'Hey, we've got this amazing thing, even built with some of your parts, and what do you think about funding us? Or we'll give it to you. We just want to do it. Pay our salary, we'll come work for you.' And they said, 'No.' So then we went to Hewlett-Packard, and they said, 'Hey, we don't need you. You haven't got through college yet.'"
- Steve Jobs, cofounder of Apple Computer
FL
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D
Deleted member 16349
Guest
Faitlux, as they say in Britain, brilliant.
This is just human nature and it is the real problem to get past. If some idea is a bit too far out on the curve, it is normal that people can not see it for what it is.
Many of the greatest ideas in mankind had to fight for their place in the sun. I think Colonel Sanders had the same problem getting acceptance with his chicken recipe.
Maybe a poor example.There are two very interesting issues here. One is that at first, only the scientists or inventors understand the importance of what they are doing and it takes then some time to get others to understand.
The second is that even the inventors above could not see what their initial concept would evolve into. They had no idea how the industry was going to develop from their initial start.
The same goes with my view of positive ink feed and some other issues that need to be corrected. I can see the near future implications but farther out is not so clear. Others, I would expect would take the new knowledge and be able to push things farther ahead. Valid knowledge is a tool that can be applied in ways that may surprise all in the future.
inkinveins
Active member
I think everyone is getting way off topic here, I thought this thread was defining " Who teaches the teachers ", It seems like whenever there is a chance to inject " Positive ink feed " into the conversation, Mr. Nikkanen and his cohort Mr. Ferrari try to push their concept on everyone, Although I am guilty of egging them on, by trying to get a true understanding of this "Concept", ( which, I will never make that mistake again ), I find it interesting there was no retort to Mr. Senefelder's skepticism which I am in total agreement with. I guess what I am saying is "prove it ". If myself and alot of other skeptics saw this succeed in a demonstration, maybe the need to defend would not be so great. Maybe there should be a seperate forum dedicated to "Positive ink Feed ", so we can segregate topics to be mutually beneficial to everyone.
BTW, I wasn't aware that Mr. Ferrari was the forum police and would of been so greatly offended by an accidental double post of a quotation, for this I am deeply sorry.
D
Deleted member 16349
Guest
Inkinveins, I have no problem with people who are skeptics. If they want to be then they should be as skeptical as they want. If the only way for them to change their minds is for successful demonstrations, I can understand that.
That is why I have said that I am happy to have history determine what was right. It is really too much effort to try and convince a skeptic to change their mind and I don't really try. I present my position and leave it at that. If you want the specific discussion to stop then don't keep asking for clarification that you can not understand or accept. Let history determine what is true.
I would add that these kinds of topics are what the teachers should be discussing but they have decided not to for many decades and long before I came around.
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I've been lurking on this thread since it started, and must say find the deviation off topic has been hugely interesting.
Why, oh, why, though has everyone got into the habit of reiterating the messages just above their own? I share Mr. Ferrari's gripe. We're all reading the same thread here - we know what's come before. All the quoting does it to spread the thread over many more pages than it would occupy otherwise.
Anyway...
Nicolas
Why, oh, why, though has everyone got into the habit of reiterating the messages just above their own? I share Mr. Ferrari's gripe. We're all reading the same thread here - we know what's come before. All the quoting does it to spread the thread over many more pages than it would occupy otherwise.
Anyway...
Nicolas
Lukas Engqvist
Well-known member
To get to the main topic of THIS thread (and I'm sure the ink feed can be almost a seperate sub-forum if all the threads are strung together). I did read Levenson's paper, a very interesting one at that, and it does give a very good insight into one institutions attitude (and as I can see a sound and balanced one). But teaching press technology and graphics is more that just ink feed. As machines get more microchips in them and are more self sufficient to monitor (to run them still means running to tinker with whatever needs tinkering, though much of the tinkering is done from the control panels in a modern press).
What other issues should the teachers be teaching? I can see that the development of ink feed, or the testing of it could be a project for one small group, for the rest a basic understanding of the theory would suffice. Should all printing students be working on it? I doubt that would be wise or of benefit to the industry. So there must be other issues for others to work with? What are they I wonder? I know many smaller print shops where the printers need to widen their competency to include imposition or post press skills, some will be trained to handle all from editing customer (and design depending on talent ) documents to post-press.
Scientific thinking. How to document problems, as Gordon points out in his link about what we can learn from engineers. How to trouble shoot. To trouble shoot in the right order, so you don't waste half a day before you stick in a hydrometer-sword in the paper stack when the day is done to conclude, "oops the paper was too dry that's why my day was wasted".
Maybe the internet and more precisely just threads like this one are the ones that are possible and necessary to bring to attention to the trainers the specific issues that need be considered. I think many teachers are not taught by an institution (that would in it's turn lead to "who teaches the teachers of the teachers" etc) rather the teachers (professors, masters or what ever they are called) get their knowlede, as do most scientists, through either listening and debating with experts and/or through conducting research/experiments.
The mindset of the expert and proffessional will also vary. Some of us will experiment whenever given the chance. Our minds buissy conjuring new ways to test and/or enhance our workflow. Others will simply do what they are required to do. Yet others will look to consultants to do it for them. Here maybe the cynic/skeptic is the one at advantage, for he/she will not simply accept the consultant or the industry standard but will question and find the appropriate experiment to test that the change is for the better. (better can mean in some cases a compromise of usability and quality).
There is another question which is perhaps more the one that Nikkanen is wrestling with: "Who is training the researchers?" or "How do we influence the research?" or possibly "How do we change the industry?". Here we come to the dilema of every visionary. Vision is probably less than 10%, for the most part for ideas to take shape we need hard work and perseverence, and some times just being at the right place at the right time with the right connections. (please don't get me wrong Erik, no offence is meant).
Remember we are the industry. If you want a change then we have to network to raise enough voice for a change. Yes there are industry organisations, and some of them are observing us. Screaming louder will not help. Being more verbose will hardly benefit, rather building trust and confidence in one another. Seeing who is and who isn't knowlegable. Being confident enough to expose our weaknesses that others may, with their knowledge help to understand the whole picture. Also knowing that our insight isn't stand or fall on just one theory.
Today this can be done, and yes, living in a day and age where intellectual property is borrowed and stolen doesn't make it easier to share freely without possibly loosing out on the credit. But in the air of democracy today we all have the power to change the rules of our profession (though unfortunately we may not be around to witness that change).
There is a parallel subject, and that is the one of how to influence the developers/manufacturers, or is it "who teaches the engeneers?"
What other issues should the teachers be teaching? I can see that the development of ink feed, or the testing of it could be a project for one small group, for the rest a basic understanding of the theory would suffice. Should all printing students be working on it? I doubt that would be wise or of benefit to the industry. So there must be other issues for others to work with? What are they I wonder? I know many smaller print shops where the printers need to widen their competency to include imposition or post press skills, some will be trained to handle all from editing customer (and design depending on talent
) documents to post-press.Scientific thinking. How to document problems, as Gordon points out in his link about what we can learn from engineers. How to trouble shoot. To trouble shoot in the right order, so you don't waste half a day before you stick in a hydrometer-sword in the paper stack when the day is done to conclude, "oops the paper was too dry that's why my day was wasted".
Maybe the internet and more precisely just threads like this one are the ones that are possible and necessary to bring to attention to the trainers the specific issues that need be considered. I think many teachers are not taught by an institution (that would in it's turn lead to "who teaches the teachers of the teachers" etc) rather the teachers (professors, masters or what ever they are called) get their knowlede, as do most scientists, through either listening and debating with experts and/or through conducting research/experiments.
The mindset of the expert and proffessional will also vary. Some of us will experiment whenever given the chance. Our minds buissy conjuring new ways to test and/or enhance our workflow. Others will simply do what they are required to do. Yet others will look to consultants to do it for them. Here maybe the cynic/skeptic is the one at advantage, for he/she will not simply accept the consultant or the industry standard but will question and find the appropriate experiment to test that the change is for the better. (better can mean in some cases a compromise of usability and quality).
There is another question which is perhaps more the one that Nikkanen is wrestling with: "Who is training the researchers?" or "How do we influence the research?" or possibly "How do we change the industry?". Here we come to the dilema of every visionary. Vision is probably less than 10%, for the most part for ideas to take shape we need hard work and perseverence, and some times just being at the right place at the right time with the right connections. (please don't get me wrong Erik, no offence is meant).
Remember we are the industry. If you want a change then we have to network to raise enough voice for a change. Yes there are industry organisations, and some of them are observing us. Screaming louder will not help. Being more verbose will hardly benefit, rather building trust and confidence in one another. Seeing who is and who isn't knowlegable. Being confident enough to expose our weaknesses that others may, with their knowledge help to understand the whole picture. Also knowing that our insight isn't stand or fall on just one theory.
Today this can be done, and yes, living in a day and age where intellectual property is borrowed and stolen doesn't make it easier to share freely without possibly loosing out on the credit. But in the air of democracy today we all have the power to change the rules of our profession (though unfortunately we may not be around to witness that change).
There is a parallel subject, and that is the one of how to influence the developers/manufacturers, or is it "who teaches the engeneers?"
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The need for print is declining, offset is a shrinking market, not a growing market. However how long it lasts is a completely different subject nobody really knows the answer to. Printing presses are incredibly expensive machines to manufacture. As different processes continue to erode offset, manufacturers will need to look elsewhere for their revenue.
Manufacturers are developing now, the printing machines (whatever type) of tomorrow. There is no point in designing and building the best machine and then finding there is no market for it!
In education institutions we are training the printers of tomorrow, so surely they need to be fully abreast of the processes they will be using, sadly the position of offset must be diminishing in the curriculum.
Manufacturers are developing now, the printing machines (whatever type) of tomorrow. There is no point in designing and building the best machine and then finding there is no market for it!
In education institutions we are training the printers of tomorrow, so surely they need to be fully abreast of the processes they will be using, sadly the position of offset must be diminishing in the curriculum.
Cornishpastythighs
Well-known member
STU, We are a packaging manufacturer running sheetfed offset and we have never been busier. There is still a lot of Offset Iron out there. Yes Digital print and Flexo has eaten away at the offset market but High quality carton printers still run a lot of offset presses. Digital presses struggle with running poorer quality substrates as us folding carton chaps have to contend with. Packaging is the one market where consistant colour run to run and batch to batch is critial. Dont ring the death knell quite yet
D
Deleted member 16349
Guest
There is a parallel subject, and that is the one of how to influence the developers/manufacturers, or is it "who teaches the engeneers?"
Lukas, Good question. Actually I am one who teaches engineers.
In 2004 I presented a course to Drent Goebel press R&D engineers in Holland called,
"Colour (Density) Control Analysis of Offset Presses for Engineers"
It was a full two day course that covered how to analyze offset presses with respect to the density control problem, in a way engineers needed, in order to be able to design presses that would have predictable performance.
It covered a wide range of issues that an engineer should understand when dealing with the design of presses or other technologies for the complicated process of offset printing.
Density control is not just about the consistency of the SID patch but it is about the consistency of the total inking of the plate, presetting accuracy, running consistency, response time etc. Understanding the causes of mechanical and starvation ghosting and how the roller train configuration has an affect on these types of issues. It is detailed enough to be able to say where rollers should be positioned and what their sizes should be etc. All of this was presented in mathematical terms, which is critical for engineers.
Positive ink feed was covered in about 15 minutes of this two day course and was presented in conjunction with the discussion of other ink feed methods and how they perform.
My technology in particular was successfully tested on their test press so the performance of it did not need to be included in any depth during this course. The tests of my technology was done with UV inks, on coated, uncoated and plastic coated substrate. Speeds up to about 500m/min were tested. Water settings were adjusted from normal to very high. The density/ink curve was determined on press in about 15 minutes. This curve is useful for a future control system so that one can go from one density level to another just by setting the new density target.
As I said, positive ink feed was a small part of the course but positive ink feed is important because many of the other issues can not be properly corrected until the ink feed questions is resolved. It is on the critical path to make the process mathematically definable. That is why I discuss it so often on this forum.
Back to education. There are no engineering schools in North America that teach press design. The graphic arts institutions have not been able to describe the process in a way engineers can understand and use to design future technologies. This has left the engineering community to use common engineering techniques such as temperature controlled roller trains and dampening systems, closed loop colour control, etc. to address the symptoms of the problems and not the fundamental causes.
The major engineering schools that deal with press technology are in Germany. From looking at their web sites and abstracts of their technical papers, it seems clear to me that they are not theoretically oriented such as MIT or the University of Toronto. The German engineering schools that are specialized on printing technology are more practically oriented and produce fine engineers that build machines.
They missed developing a science to explain the offset density control process because I think they educate engineers to build presses expecting that experienced operators will operate them. Anyhow these schools seemed to have lost interest in offset and are now heavily working on technologies for printed electronics.
As a engineer, I can understand how frustrating it is for other engineers to deal with printing related issues. I also understand that they don't know what is required. That is one reason I have developed a science to fill that gap.
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D
Deleted member 16349
Guest
Hi Stu, two points.
I would say that the press manufacturers are not developing the machines of tomorrow because they are not sure how to progress.
The market will be there. Totally it will be a smaller market but if one press manufacturer builds a really newer technology at the right price, they can actually grow as they take market share away from others. That's the opportunity and that is the only way out for a press manufacturer.
That is the way other industries work. Continual competition based on the development of innovation aimed at taking market share away from competitors. Much of that innovation is based on developing the science that supports new technologies. That science is a result of a cooperative effort between industry and high level science and engineering universities. Valid science is the prerequisite for better technology.
There is still a great opportunity for one or two press manufacturers to take market share but they have to change their thinking and approach. They have to think that their survival requires the destruction of their competition by means of better technology based on more valid science.
The present situation where everyone makes basically the same press has just lead to all going down together.
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Mark H
Well-known member
This is the same discussion/argument that every industry has with traditional institutions of higher education - "you don't teach the real world skills I need new employees to have in order to be productive." As others have mentioned, this highlights the difference between an education and training for a job.
When I hire a new programmer I look to the 2-year state run technical colleges for candidates. What I find are people who are hungry for an entry-level job, have received just enough education to know what they're getting into, and who aren't so over educated that I will have to break them of bad habits or spend time arguing with them about why they shouldn't do something the way their professor showed them.
Mark H
When I hire a new programmer I look to the 2-year state run technical colleges for candidates. What I find are people who are hungry for an entry-level job, have received just enough education to know what they're getting into, and who aren't so over educated that I will have to break them of bad habits or spend time arguing with them about why they shouldn't do something the way their professor showed them.
Mark H
Harvey Levenson
Member
Dear Colleagues,
Sorry for the delay in responding to the more recent communications about “Who teachers the teachers?” I am enjoying the dialogue but needed to find some time amidst a busy schedule. I’ll address (1) the “positive ink feed” theory and (2) teaching graphic communication.
(1) First I will address three quotes with my notations following each.
“A positive ink feed, by what ever means, that goes directly into the high speed roller train, which will not be disturbed by any changes in the variables above, will result in very consistent print density. One cannot wash the print out.”
I’ve run presses and owned one. Ink density is impacted by more than ink feed. Even in electronically controlled presses, regardless of ink feed, water can change. But there is more. Density is only relevant on the printed sheet. Once ink is fed into the ink train, positive feed or whatever, there are a myriad of dynamic variables that have to be controlled. They are dynamic because they are mechanical variables and can cause change in the system–heat, speed, pressure, wear, chemistry, etc. If anyone is interested I can provide workable tolerances for each because I’ve measured them on hundreds of presses and thousands of press units in about 250 companies where I’ve been a consultant during over my 49-year career (I’m just getting started). This is not theory. This is reality.
Some of these variables include:
- Plate-to-blanket squeeze (differs for compressible vs. conventional blankets).
- Ink film thickness (differs for sheetfed or web on 1st steel oscillating roller above the form rollers on the opposite side of the dampening system).
- Fountain solution formulation, pH, and conductivity.
- Form roller settings to the plate and from side to side.
- Form roller and distributor roller durometer (changes with wear and impacts ink distribution).
- Ink tack (force required to split an ink film from the a surface; differs for sheetfed and web).
- And much more.
“There will be no balancing of ink and water. One sets the ink feed rate for the image requirements and one sets the water for the plate conditions. Adjusting the water will not affect the ink feed rate which in turn will provide consistent print density.”
See my note above. There is a lot more than ink and water than impacts density on the sheet.
“Theoretically this is based on the principle (not theory) of Conservation of Mass. The amount of ink going out of the press must be equal to the amount of ink going into the press when the press is at steady state conditions. The balance of the mass of ink in and out of the system is independent of any other variable.”
“Theoretically… (not theory)”? Which is it, theory or not theory? It can’t be both. However, it is theory and has no practical application because, as any experienced press operator will confirm, in reality no press is always in a “steady state [of ] conditions.” This will never be until all cylinder configurations, roller dynamics, and other mechanical variables are removed.
So the theory is that, “The amount of ink going out of the press must be equal to the amount of ink going into the press… .” I agree. However, as Al Ferrari astutely pointed out, the way the ink behaves and is distributed in the press impacts the final density on the sheet. For example, the ideal situation is a 50:50 split of ink at each transfer point such as from ink fountain to distributors rollers (roller-to-roller) from the final distributor roller to the form rollers, from the form rollers to the plate, from the plate to the blanket, from the blanket to the press sheet. If there is anything more or less than a 50:50 split between each of these points there will either be ink buildup or ink starvation in the printing unit, both of which impacts density. Because of the mechanical dynamics previously referred to, a 50:50 split is nearly impossible to maintain consistently. Hence, there are ongoing adjustments required, even in presses having electronic controls, well beyond ink feed, that influences density.
(2) Teaching methodology at Cal Poly has been brought into question. I will address that by a WWT blog by Brian Lawler that is soon to appear.
When 13 people on a press is a good thing - Blognosticator
I always accept positive criticism and would like to know if anyone takes issue with the teaching approach described as it reflect the entire teaching methodology at Cal Poly–hands-on and “learn by doing.”
Best wishes to all of my colleagues on this site.
Harvey Levenson
Dept. Head
Graphic Communication Department
Cal Poly
Sorry for the delay in responding to the more recent communications about “Who teachers the teachers?” I am enjoying the dialogue but needed to find some time amidst a busy schedule. I’ll address (1) the “positive ink feed” theory and (2) teaching graphic communication.
(1) First I will address three quotes with my notations following each.
“A positive ink feed, by what ever means, that goes directly into the high speed roller train, which will not be disturbed by any changes in the variables above, will result in very consistent print density. One cannot wash the print out.”
I’ve run presses and owned one. Ink density is impacted by more than ink feed. Even in electronically controlled presses, regardless of ink feed, water can change. But there is more. Density is only relevant on the printed sheet. Once ink is fed into the ink train, positive feed or whatever, there are a myriad of dynamic variables that have to be controlled. They are dynamic because they are mechanical variables and can cause change in the system–heat, speed, pressure, wear, chemistry, etc. If anyone is interested I can provide workable tolerances for each because I’ve measured them on hundreds of presses and thousands of press units in about 250 companies where I’ve been a consultant during over my 49-year career (I’m just getting started). This is not theory. This is reality.
Some of these variables include:
- Plate-to-blanket squeeze (differs for compressible vs. conventional blankets).
- Ink film thickness (differs for sheetfed or web on 1st steel oscillating roller above the form rollers on the opposite side of the dampening system).
- Fountain solution formulation, pH, and conductivity.
- Form roller settings to the plate and from side to side.
- Form roller and distributor roller durometer (changes with wear and impacts ink distribution).
- Ink tack (force required to split an ink film from the a surface; differs for sheetfed and web).
- And much more.
“There will be no balancing of ink and water. One sets the ink feed rate for the image requirements and one sets the water for the plate conditions. Adjusting the water will not affect the ink feed rate which in turn will provide consistent print density.”
See my note above. There is a lot more than ink and water than impacts density on the sheet.
“Theoretically this is based on the principle (not theory) of Conservation of Mass. The amount of ink going out of the press must be equal to the amount of ink going into the press when the press is at steady state conditions. The balance of the mass of ink in and out of the system is independent of any other variable.”
“Theoretically… (not theory)”? Which is it, theory or not theory? It can’t be both. However, it is theory and has no practical application because, as any experienced press operator will confirm, in reality no press is always in a “steady state [of ] conditions.” This will never be until all cylinder configurations, roller dynamics, and other mechanical variables are removed.
So the theory is that, “The amount of ink going out of the press must be equal to the amount of ink going into the press… .” I agree. However, as Al Ferrari astutely pointed out, the way the ink behaves and is distributed in the press impacts the final density on the sheet. For example, the ideal situation is a 50:50 split of ink at each transfer point such as from ink fountain to distributors rollers (roller-to-roller) from the final distributor roller to the form rollers, from the form rollers to the plate, from the plate to the blanket, from the blanket to the press sheet. If there is anything more or less than a 50:50 split between each of these points there will either be ink buildup or ink starvation in the printing unit, both of which impacts density. Because of the mechanical dynamics previously referred to, a 50:50 split is nearly impossible to maintain consistently. Hence, there are ongoing adjustments required, even in presses having electronic controls, well beyond ink feed, that influences density.
(2) Teaching methodology at Cal Poly has been brought into question. I will address that by a WWT blog by Brian Lawler that is soon to appear.
When 13 people on a press is a good thing - Blognosticator
I always accept positive criticism and would like to know if anyone takes issue with the teaching approach described as it reflect the entire teaching methodology at Cal Poly–hands-on and “learn by doing.”
Best wishes to all of my colleagues on this site.
Harvey Levenson
Dept. Head
Graphic Communication Department
Cal Poly
Green Printer
Registered Users
Harvey Levenson
Dept. Head
Graphic Communication Department
Cal Poly
Harvey I think you are 110% correct.
Dept. Head
Graphic Communication Department
Cal Poly
Harvey I think you are 110% correct.
Al Ferrari
Well-known member
Professor Levenson, you write:
"Once ink is fed into the ink train, positive feed or whatever, there are a myriad of dynamic variables that have to be controlled. They are dynamic because they are mechanical variables and can cause change in the system–heat, speed, pressure, wear, chemistry, etc. If anyone is interested I can provide workable tolerances for each because I’ve measured them on hundreds of presses and thousands of press units in about 250 companies where I’ve been a consultant during over my 49-year career (I’m just getting started). This is not theory. This is reality.
Some of these variables include:
- Plate-to-blanket squeeze (differs for compressible vs. conventional blankets).
- Ink film thickness (differs for sheetfed or web on 1st steel oscillating roller above the form rollers on the opposite side of the dampening system).
- Fountain solution formulation, pH, and conductivity.
- Form roller settings to the plate and from side to side.
- Form roller and distributor roller durometer (changes with wear and impacts ink distribution).
- Ink tack (force required to split an ink film from the a surface; differs for sheetfed and web).
- And much more."
How many of the press units referred to above had positive ink feed and how many had whatever other ink feed?
How did these measurements compared between the two groups?
In my response to Cornishpastythighs I listed 5 categories of ink transfers and stated that in a positive ink feed system the effect of water is eliminated from the first category, but would continue to affect the others (the post may be worth revisiting). We are indeed fortunate to have the large body of data from your measurements to use in evaluating the effect of water and the associated fountain chemicals on the two types of systems. Perhaps you have already summarized these comparisons and could provide a reference for us.
Thank you in advance.
Al Ferrari
"Once ink is fed into the ink train, positive feed or whatever, there are a myriad of dynamic variables that have to be controlled. They are dynamic because they are mechanical variables and can cause change in the system–heat, speed, pressure, wear, chemistry, etc. If anyone is interested I can provide workable tolerances for each because I’ve measured them on hundreds of presses and thousands of press units in about 250 companies where I’ve been a consultant during over my 49-year career (I’m just getting started). This is not theory. This is reality.
Some of these variables include:
- Plate-to-blanket squeeze (differs for compressible vs. conventional blankets).
- Ink film thickness (differs for sheetfed or web on 1st steel oscillating roller above the form rollers on the opposite side of the dampening system).
- Fountain solution formulation, pH, and conductivity.
- Form roller settings to the plate and from side to side.
- Form roller and distributor roller durometer (changes with wear and impacts ink distribution).
- Ink tack (force required to split an ink film from the a surface; differs for sheetfed and web).
- And much more."
How many of the press units referred to above had positive ink feed and how many had whatever other ink feed?
How did these measurements compared between the two groups?
In my response to Cornishpastythighs I listed 5 categories of ink transfers and stated that in a positive ink feed system the effect of water is eliminated from the first category, but would continue to affect the others (the post may be worth revisiting). We are indeed fortunate to have the large body of data from your measurements to use in evaluating the effect of water and the associated fountain chemicals on the two types of systems. Perhaps you have already summarized these comparisons and could provide a reference for us.
Thank you in advance.
Al Ferrari
Alois Senefelder
Well-known member
from a "Stone Age Relic"
from a "Stone Age Relic"
To Mr. Harvey Levenson, Dept. Head
Graphic Comminication Dept. Cal Poly
Congatulations - 100 % in agreement.
Regards, Alois
from a "Stone Age Relic"
To Mr. Harvey Levenson, Dept. Head
Graphic Comminication Dept. Cal Poly
Congatulations - 100 % in agreement.
Regards, Alois
D
Deleted member 16349
Guest
This is getting to be a bit sad. The more you comment on these issues, the more it will eventually show that you do not understand the fundamental issues of this process even though you have extensive experience.
Conservation of Mass is not considered just any theory. It is a principle of physics. It is a Law. Like the Law of Conservation of Energy or the Law of Conservation of Momentum. These are some of the building blocks of physics and any theory MUST comply with these Laws.
Regarding differences in ink split. Different ink split ratios will have no affect on the mass flow through the press when one has a positive ink feed. One can do a roller train ink distribution calculation. Compare one calculation that uses the 50/50 split with another calculation of the same roller train that uses 60/40 or any other split ratio. The ratios can even be different in different nips. The result will be that both calculations will show that the ink out will be the ink in and they will be the same for each.
Interactions in a press are complicated but they do not create or destroy the mass of ink. You agree that ink in must equal ink out but they you imply that some variables in the press will mean that even though there is the same amount of ink on the paper, the density will be different. The implication is that density is NOT closely related to printed ink film.
Your views seem to be based on a long history of observation by you and press operators of how the process works but I suspect that all that history is based on presses that did not have positive ink feeds. Trying to assume that the performance of a process where the major variables is not controlled is going to be similar to the performance of a process that does have that variable controlled is not wise. You could be in for a lot of surprises.
Again, I will say that I am happy to let history decide. You are on the wrong side of this issue and the more you say just makes it worse. History will be the judge.
Mark H
Well-known member
Erik,
I don't believe that you are interpreting and applying the principle of mass/matter conservation correctly in this discussion. While it is true that that the mass of a closed/completely isolated system will remain constant over time, mass is not conserved in "open" systems when forms of energy are allowed into or out of the system. This is especially true in systems where work, or motion, are in progress or where chemical reactions or chain reactions are occurring.
A press, even a very well maintained one under laboratory conditions, would still be an open system and therefore not fall within the law of Conservation of Mass.
Mark H
Al Ferrari
Well-known member
Addresin Erik, Mark H writes:
"I don't believe that you are interpreting and applying the principle of mass/matter conservation correctly in this discussion. While it is true that that the mass of a closed/completely isolated system will remain constant over time, mass is not conserved in "open" systems when forms of energy are allowed into or out of the system. This is especially true in systems where work, or motion, are in progress or where chemical reactions or chain reactions are occurring.
A press, even a very well maintained one under laboratory conditions, would still be an open system and therefore not fall within the law of Conservation of Mass."
Mark,
So in presses with positive ink feed which as you say are open systems, what happens to the ink that does not go onto the substrate?
Al Ferrari
"I don't believe that you are interpreting and applying the principle of mass/matter conservation correctly in this discussion. While it is true that that the mass of a closed/completely isolated system will remain constant over time, mass is not conserved in "open" systems when forms of energy are allowed into or out of the system. This is especially true in systems where work, or motion, are in progress or where chemical reactions or chain reactions are occurring.
A press, even a very well maintained one under laboratory conditions, would still be an open system and therefore not fall within the law of Conservation of Mass."
Mark,
So in presses with positive ink feed which as you say are open systems, what happens to the ink that does not go onto the substrate?
Al Ferrari
Last edited:
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