problem with cyan feeding into the yellow ink unit

We have started having a problem with cyan ink feeding through to the yellow ink train And turning the yellow green
Any ideas the press is a komori 526 damp and rollers set as per manual
Fount has 2% sf1 and 6% alc Inks have been running fine until last week
Cheers Tim

 

Hi timc

sounds like overdampening in either cyan or yellow. This can cause emulsification and so affect the tack of the ink - once the tack values change you get 'pick up' of one colour into the next.

It can also happen if you are running a lot of cyan but little yellow. Does it happen on all jobs or just now and then?

Try easing the damps down. If all you get is catch up then you'll have to ease the tack of the yellow with a 5% max addition of gel reducer in your yellow.

What ink set are you running? What damp ratio settings do you carry?

If all fails you may need to look at your fount/alcohol combination.

We run 2for1 fount (replaces our old IPA and Varn Supreme mix) from Vision Inks (Long Eaton) on our L626, it's the best move we ever made. Sharper dot, stable colour and no IPA.

 

we(because I'm not machine operator!) got the same problem too.reducing the yellow tack give better result but still effect the ink after long run.

 

cheers for the help

damps set at 145 ratio med start up Inks 150
If this helps Would lowering the font additive help ???

 

Any chance of taking a pic of your problem job and posting it here?

It may just give a clue.

Did you try the reducer?

 

how about using "medium"(in form of like ink) work same like reducer(totally oil) give more sharp tone.there no point to adjust your water ratio high because it may lead to another problems like scumming etc and the worse is just like pic attach above.well i dont know about your press condition but our LS540 give me a backache because we manually wash the plate and blanket. imagine for 100000 sheet,10 ups for 1 job running in 2 shift you do the wash manually. ink deposit outside the non-image area. i knew 1 of the reason was the fountain solution condition-conductivity,pH but dont surprise because we dont have any pH or conductivity meter.just let the fountain circulator do the job. dont blame me richard i just no body with 1 and half year experience in printing just waiting my turn to take over this press. see the pic and you can imagine what would happen to yellow ink.pic above is cyan at 4th unit and 5th unit is yellow.

 

I never had fancy blanket washers until 2 years ago and we still don't have impression cylinder washers.
So I know where you're coming from.

Your pic looks like seriously emulsified ink, way too much damp or contaminated (with solvent)... is that the water pan roller, wow!? If you're getting that you need to try a different fount/alcohol combination that doesn't break the ink down so much.

 

may have sorted it

I have dropped the dose of fount solution being mixed And today the yellow has run clean Just need to work out if the doser is wrong on the calibration

 

Your pic looks like seriously emulsified ink, way too much damp or contaminated (with solvent)... is that the water pan roller, wow!? If you're getting that you need to try a different fount/alcohol combination that doesn't break the ink down so much.[/QUOTE]

seriously no! that was blanket!!!!!!!! look so damn shiny haaaaa

 

Yup! That's emulsification alright!

And look at me, I can't tell the difference between a blanket and a pan roller...

 

dropping the fount has helped But still a slight tint of blue coming in after 2000 sheets May try different ink See what happens Suspect it may be the tack

 

Yes, get that emulsifaction under control and I would suggest you talk to your ink supplier sales rep. Perhaps tack levels were adjusted at manufacturing, either cyan is too low or yellow is too high.

 

Well the problems gone I can only put it down to 2 things
1 fount mix to high
2 Change blankets to a harder blanket
And the problems gone !!!!!!!!!
Printing can be really strange at times

 

yellow contamination

i have found that if my yellow ink (which is usually always run last down) is getting contaminated by another color its as a result of either a yellow ink film thats too thin or one of the other colors before the yellow being run too high. when it comes to ink tack one thing to remember is that a thin ink film is is usually tackier than a thicker ink film. that being said you can usually keep the yellow ink clean by either reducing the tack (which can bring on its own set of issues) or by diluting the ink strenghth with some transparent white and then running a thicker ink film. Id opt for the later whenever possible!!! perhaps you had a batch of yellow ink that was formulated with a very high pigment load. if that was the case then you would have to had run less yellow to arrive at color. less yellow equals more tack, more tack equals contamination!!! look at the batch numbers of the inks you used when you were having the problem if still available. then compare it to batch numbers that were pre problem or post problem. keep your eyes open for trends like this and dont be afraid to do a little testing to prove out suspicions. one tip off to this happening is to look in the ink fountain at the ink in zones of very light coverage. if you see the yellow ink getting more dirty in these areas its a pretty good indicator of too thin an ink film. always try to feed enough ink into zones with no image to keep the density of your color bars in that zone up to standard.

 

we got round this problem by running a harder blanket on the cyan !!!!! go figure it worked for us

 

tel your ink maker to reduce the frickin tack of your process yellow!

Rod (old school)