Plate Blinding on Lithrone

Hang new set of plates and all looks great. After awhile - 3,000 to 5,000 impressions - M plate starts to sensitize (looks like breaking down but just starts to blind) on finer percentage dots. Have also noticed on C unit as well but am still trying to find a consistent pattern. Have been running same dampener fountain solution and ink for 6-9 months and this is a fairly new development. Any thoughts?

 

If

If the surface of the plate is not that strong and you have Delta effect on your press . it could damage the plate's grain rather fast.
Did you change your plat batch ?
any change to your basic water ? do you know the hardness ?

 

If it's happening on all the units, I would suggest the problem is on the plate side.

 

Plate Blinding

The sensitivity (blinding) only happens on the M and C units. It starts out somewhere in the 5000 impression range and then the plate appears to be breaking down. Upon inspection of the plate, it is actually blinding. It begins with the very fine dots and then gets worse from there. I don't think it has anything to do with plating because again, it is only on the M and C units.

Any thoughts about this.

 

What is Delta effect?

 

Delta effect / system

To keep your print cleaner (important for packaging / board printing) the press has one roller on the plate that turnes in a different sped (faster/slower) then the plate , to clean the plate from paper dust. this is very good for the printer , but not as good for the plate as it will increase the ware of the plate. so unless you bake your plates , they will hold less then without it.
Why only on C & M ?
That is due to the 2 inks having more calcium in them - harder base , so you also get more calcium on your rollers and that will get your plate ware even more (plate beinbg rubbed by the roller)
First give all your rollers a very good & deep clean to get any calcium out,
Make sure your rollers are the right shore# , i.e. as soft as they should be (what model is your press???) and if you can , try getting a set of baked plates.

Some plates will hold better , some will nopt hold at all (can't put any names on the forum but will give you advice if you contact me outside the forum - i do not want any plate company sending me big guys with sticks

That is your issue , nothing basice wrong with your press , just get it right

Where are you from ?

Meny
+972-523201671 direct

 

Delta Effect

That sounds reasonable as I have noticed hickies pick up on the plate while printing and then sometimes they disappear on their own. I never knew about the off speed roller, that's good to know if this model has it. It's an L428.

Thanks for the number and I will contact you if it's ok maybe tomorrow?
I live in the PNW and sometime in the AM if that's alright.

I have your number now so you can edit your post and delete it if you want.

 

If the image is still on the plate but it is no longer printing it sounds like the gum in the etch is desensitizing the image areas of the plate. If you can you should check the p.H. of the fountain solution. If you are using tap water for your fountain solution, tap water can change over the year based on what is added to the water supply. If this is a rather new development it is possible that a change in the township water treatment is affecting how it's running. It's also possible that your picking up contaminates from the paper that is affecting your printing. Is this a new paper? A new batch? Does this happen right after you mix fresh solution or does it only show up later in the week?

 

Feel free to call any time

 

How old is the press? Delta wasn't on all machines. With it predominantly affecting magenta/cyan I would be looking at contamination from the water supply. What is the water hardness, which fount do you use, do you have a roller cleaning/maintenance regime in place?

YG

 

alibryan

Have seen that many times over. To fix the problem right now put copper plating solution on the roller train. Now to stop it in the future you need to change the way and the roller wash that your using. Go to a water misable wash and use water at the end of the roller rinse, lots of water. then on the last shift of the week put copper plating solution on to sit for the weekend and all will be good for the next week.

good luck
FSA

 

A plus & a minus in every thing...

This could give him foam the next week if he dose not change all his water and clean ity very well.
and the foam will bring other problems...

 

hey Meny do you run presses or just sell them, i've done 1/2 a billion impressions on Komori 40" machines, foaming in the water tank, not ! Blinding starts 99% of the time in the magenta unit, why, it's the pigment in the red huge. As the roller train wears, the copper plated rollers tend to need more tlc, i don't have problems with any printing press, just other operator and there bad habits ! I run and fix press daily, just to prove a point at one shop the magent was blinding(what a surprize) and put 1 oz of copper plating solute on the ink train while the press was still printing,boom it was gone.
Salemans should stick to selling, if you don't know the answer keep it to yourself.

FSA

 

The real problem has been prevalent for some time now. The fact that two seasoned pros can come back with two different answers isn't the half of it. Thanks for the help though , I appreciate it.

Are there any other online versions of my situation?

 

I am sure there are many similar situations on line. Have you tried doing what FSA has said because he is more than likely right. How old is the press? Delta can cause problems. I can tell you if that is the case if you answer.
By the way, the copper rollers aren't plated they are 2mm copper tube fixed to the rollers but do get desensitized and respond well to copper solution.
If you are looking for a magic answer there isn't one, but the answer is in this thread.

YG

YG

 

I haven't tried copper plate solution yet but have been decalcifying for a couple days. I have noticed an improvement but can't be sure yet. Will know more in a couple days. I have been told that the problem is a calcium build up.

Are you saying that the copper rollers are reacting with the cyan and magenta ink (haven't noticed any problem with black and yellow) and contaminating the ink enough to cause blinding?

 

yes and no

The M & C have a backbone of Calcium in them , and that makes them harder.
If you use Alcohol , you get more of the ink broken when it mixes with the ink , and you get even more calcium out on your rollers.

I was told in this thread to keep quite and mind my own business (well i am not in the business any more - just looking to help if i can.... so i will allow my self to answer...

Adding to this , the emultion on the new CTP plates is not as hard as in the older plate made with film , and they are way more sensitive to the chemicals & rubresistance lower too. so if you have calcium issues on your rollers , Alcohol in your ink and the rubbing of a speed reduction system on the plate (Delta) , you get less out of each plate.

Solution - what you can do to keep your plates longer is having less rub on them , - get rid of Calcium deposits on your rollers. lower your Alcohol as far as you can or move to Alcohol free (you can't switch Delta off on a Komori 428) or you can try the old plates that would hold for ever....

Put on an old set of film based plates and run it - you will not loose any image for a long run.

That's my input....god luck
Meny

 

The copper rollers aren't reacting with the ink. The coating of calcium from the ink pigments, paper etc has made a film on them which is hygroscopic instead of grease attractive. You really should take the copper rollers out and clean them with a rubbing compound, then use copper solution when they are back in the press. It wouldn't harm to give the rubbers a deep clean by hand too.
If the press has Delta you can't switch it off but you can remove the damper gear from the roller (this will likely give other problems). The permanent fix is to change the oscillator drive gear to a normal ratio one as in a non delta press.

YG

 

alibryan

Get the copper plating solution and watch the results. I'll bet your running alcohol, and that the press has over 100 million on it. Every machine type has it's draw backs, some are harder to deal with than others, this is a simple one. And a easy fix , try it man
FSA

 

Thank you

To those who responded, thanks. I am using the ideas you guys listed and am having some positive results. I haven't tried everything yet but I am still optimistic because it is getting better. Should know for sure in a couple more days.