Need some help from the offset press experts...

Alois Senefelder

Well-known member
Help is at Hand !

Help is at Hand !

Hello Alith7

Having received excellent advice from the contributors, especially "Gordo" -- may I advise you to look at all the PDFs I have posted on this forum, I'm you sure you wil find something of interest and value.


Regards, Alois
 

Paultheprinter

Well-known member
hi there,

i have read most of the posts and feel your frustration, you need feedback from your pressman. Most of the info to find out cause and effect lies within the color bars, there my closest friend and worst enemy. In the real world most directors dont give a shit if your mid tone is at 20% gain on gloss they would`t care if a 50% is printing at 52 on an offset ! If your getting poor results off the press its probably due to the operators. There is virtually no training program out there which teaches the printer where a job should lie in terms of gain weight trap etc and how to achieve this if there out of target. Its down to individual companies and there policies which dictate there willingness to achieve set standards and maintain them. Set ink wights and gains for stock then optimize your settings over time if you pressmen want to keep there jobs set them boundries, but make them realistic.

Paul
 

gordo

Well-known member
There is virtually no training program out there which teaches the printer where a job should lie in terms of gain weight trap etc and how to achieve this if there out of target. Its down to individual companies and there policies which dictate there willingness to achieve set standards and maintain them. Set ink wights and gains for stock then optimize your settings over time if you pressmen want to keep there jobs set them boundries, but make them realistic.


You touch on an important point. Who is responsible for what.

IMHO, in simple terms:

Management's responsibility (with input from prepress, press room, and sales) is to establish what the targets and tolerances (dot gains, standards, specifications etc.) are for the presswork - because those are marketing/business decisions. Then provide the tools to allow prepress and pressroom to achieve those targets.

The responsibility of prepress is to align proofing to the target established by management as well as to maintain proofing within the tolerances established by management because tolerance targets are also marketing/business decisions. Prepress also must output plates that enable the press operators to align their presswork to the proofs with the press performing in a repeatable stable condition.

The responsibility of the press operator is to manage the press in such a way that the the films of the appropriate inks are laid down in a manner that meets the targets and tolerances (hue, trapping, etc.) established by management and that the halftone dots on the plate are reproduced with fidelity on the various substrates (slur, doubling, etc.). Also, the press operator needs to make sure that all press-related consumables (fountain solution, inks, etc.) are within the tolerances needed to achieve the management defined targets for pressroom output.

best, gordo
 
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Alois Senefelder

Well-known member
Color for Pressmen

Color for Pressmen

Alith7

A PDF -- Color Seminar for Pressmen (Product Summary)


Regards, Alois
 

Attachments

  • Color Seminar # 1001.pdf
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TheProcessIStheproduct

Well-known member
OK, lots of technically accurate suggestions have been made, but I would caution against moving the goal posts to dramatically, if you change blanket, rollers, fount solution, ink sets, RO water, new plates, etc... I can guarantee you will have more problems then you started with because something is not going to work and with a hundred new variables you will not know what to fix... so keep it simple to start,

work towards printing a gold standard with the density and dot gain you want

push real hard for a scanning spectro unit on press (hand scanning will make you only as good as your operator is willing to work)

if you really want to change consumables start with plates and ink, it always seems like if you have a problem it comes back to those two variables...
 

graficworx

Well-known member
I think you have identified many areas that need to be addresses. There are literally hundreds of variable that effect output from customer to press sheet. I think something you should address first is the ink. If you can visually see a difference in the ink from batch to batch, then that leads me to wonder if the milling changes, which can effect particle size and suspension.

If you have a local INX dealer, give them a call. I have used INX ink for many years, and have neve had any issues. They are generally very knowledgable, and can suggest a good fountain solution for your press as well to match the ink and plates you are using. That would take care of the ink triangle: ink, water, plate. This would include cleaning the recirculation system as well.

Next, consider a very thorough cleaning, using paste on the rollers, pumice if necessary. Make sure to get into the bottom form rollers. If you can, have the pressman pull out the entire roller train, ink and water (carefully of course), and clean them off press first, then put them back on press and clean again. While they are out, clean any area of the press that can be reached.

Third thing I would suggest is a new set of blankets.

The temperature, humidity, air quality, and air flow in the predation are also something to consider, although they can be mitigated if the press is kept in tip top shape.

Sometimes I think managers and owners that have never been press operators really don't understand what is going on, so they can't understand how to fix it. I started out at the bottom before I was able to own my own shop, then have employees. I think it gives a better perspective of what's really going on. If my pressman has trouble with something, I can actually understand what he's talking about. I've also been very pro-active in maintenance. My father taught me that, and I think it helps out in printing. Changing blankets, rollers, and pro-active cleaning, even on our 3302 or 360, seems to help keep problems down, and downtime to a minimum.
 

Lukas Engqvist

Well-known member
@Theprocessistheproduct in my experience swapping plates is not always a good way to do it. Blankest and ink yes, plates no… but just in case it isn't a bad idea to verify it's not the plates if you suspect the plates. Set in a new batch of plates measure them and confirm that all is as it should. But as in all processes it is important that in house thresh holds are low enough, and all are on the "same team" so that fingers don't start pointing but a discussion how to solve (and predict and prevent) the problem are in focus.
 

BeauchampT

Well-known member
It really sounds like an issue with your pressmen. I work on a press with a variety of operators with different skill levels and abilities. One skill that often gets overlooked is dot gain troubleshooting for colour consistency.

What sort of workload do your operators have?? Are they stressed to the limit, desperately trying to get job after job out, barely able to keep up with the load? If that is the case, they will barely have the time to, or energy to care about, dot gain, packing condition, etc, etc. If that s the case, you can do them a world of help by taking their side with management - let them get some more help and time for proper maintenance and troubleshooting.

If it isn't an overworked group of operators, then they just don't care enough to fix the problem. They need to get some good training from qualified trainers. There are lots of options out there, but, why not direct them to this sight, or helpful individuals on it? A community of peers can do wonders to help expand the ability and insight of individuals in their disciplines.

From a sympathetic pressman
 

spigot

Well-known member
Have you examined your environment as a whole? Its all very well to attempt to isolate who is responsible for what, however often you get an obstructive response if there are other problems. What I mean is, its always so easy to blame the press operator.

It is also very easy to fly in and complain about the colour consistency and proceed to tell a qualified person how the world goes round. Some may be offended and then not help.
That said, it is not rocket science. Its just frustrating and thankless work.

I focused on a few things. Firstly, the cleaning. The press must be maintained very well to have a hope of consistency. IE washups with past once per week, dumping fount around 1 time per month, checking basic settings at least 2 times a week. Have maintenance performed by a proper engineer, checking imp pressures, gears, grippers, etc etc twice a year.

then, I would keep logs of things. Blanket change intervals, Plate average runs, Conductivity and PH of fount, sometimes graphing them and occasionally finding a correlation between a current issue and a press condition.
Consumables - already said. Ink, plates fluids and sundries must be consistent.
Stock- Is just about the only variable you cannot control fully.
Environment - Unless you a printing on the beach you should be able to set standards here.

Prepress - Make sure the operators understand that the problem does become some one elses after they measure a couple of screens and declare it perfect. There can often be more issues with the calibration and curves than is immediately obvious. At least, There can sometimes be.
 
Your pressman should be using a torque wrench to tighten the blankets when they change them and then retorque a new blanket after a few thousand impressions. Improperly tightened blankets [loose blankets] with cause dot gains and if you have different people putting the blankets on they will not be tightening them the same without a torque wrench. On our presses we torque them to 40 lbs. Is anyone overpacking your blankets to fix a mash or low spot this will also cause dot gains.
 

saso777

Active member
I agree a very important factor and and if it is improperly tightened(or not good quality blanket)can cause dot gain.
 
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Alith7

Well-known member
oops...got behind on this....

I'll catch up on everyone's posts this weekend, but the torque wrench idea is a REALLY good one! I'll bring that up to my pressmen.

as an update, the owner has conceded that he will try to get me a FULL DAY to get to zero again and re-calibrate both presses. I've never been allowed to do this before! it was always, just fix it good enough to get us by! this was allowed because he FINALLY got some insite into the hacked way our curves are configured and he was so confused that he said to just fix it for now and in the next couple weeks we'll find time to fix it correctly! YAY!
 
It sounds to me that you are trying to "polish a dog poo". You have ambitions for your self and seem keen to do a job properly and I applaud you for that. You are obviously frustrated by the lack of action and support you are getting from your boss and pressman. They both seem very stuck in their ways and reluctant to change or take another's advice.
The reality is that it is a medium sized shop with a very old "main" press. The age of the SM (is it an SM as I didn't think they built them as early as 1985) alone causes me some concerns. Unless it is meticulously maintained then you are never going to produce the quality you hope to achieve, no matter how calibrated the pre-press end is with a press that old. Plus, any pressman worth his salt is already doing the majority of press related suggestions in this thread. If yours isn't, well......
Also, is the company losing lots of money and clients through re-makes? If it isn't then your boss has no reason to fix something that isn't broken.
As usual this thread has provided us with many great posts from very knowledgeable people and is a great resource for solving problems. I think the best way you can solve your problem is to change the curve when the boss asks you to and quietly get your resume out there and get yourself in a position in a bigger organization where your dedication, hard work and effort will be rewarded.
As the saying goes "onwards and upwards".
 

Lukas Engqvist

Well-known member
@Alith7 :D great to have a day to set things straight. We found that as we worked as a team and got control over our production it helped bring us closer as a plant. Wish you success! And hope your owner will be encouraged by making a good investment!
 

maas

Well-known member
Use the old adage "you cannot manage what you do not measure" and get a pull sheet from every run, measure the SID and dot gain, this will highlight any mechanical discrepancy and press crew expertise, i suggest you benchmark SID target for the crew to run to and performance manage non compliance.

regards
Maas
 

turbotom1052

Well-known member
this sounds to me like a very familiar scenario. Someone mentioned trying to polish a poo. I call it "trying to make a silk purse out of a pigs ear" The first question i have for you is what kind of leadership do you have in your pressroom. You mentioned being the prepress manager. Is there a qualified guy "in charge" of the pressroom. It never ceases to amaze me when i see a company place so much emphasis on qualified leadership in the prepress dept. or in the office but seem to think that the pressroom will find its own way. The very fact that you (as a prepress manager) have to come to this forum to find out how to put ink on paper leads me to think its one of 2 things. Either you dont have a supervisor in your pressroom, or the person youve got is either the bosses nephew, or some other incompetent. When you consider that in most cases your pressroom is you highest cost center in the entire process, from the taking of the print order to the final delivery it blows my mind that some companies negate the need for experienced leadership in that dept.
 

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