strange magenta strip

[shaneo1967]

Hi People,

i have a ink strip in the middle of the of my magenta. it appears random and drops a strip of ink on the plate . after about 20 sheets gone.

has any one had this happen to them before.

cheers

shane

 

[Hawker]

Hi Shane , hard to say without looking at it. Where a bouts in aus are you?

 

[Paul Cavanaugh]

When you say you have a strip, do you mean a toning line?

First I must admit I am not an expert in ink development, that beng said I did speak with someone who was.

We were noticing that the magenta unit tended to tone before the other units it the temperature of the room started to go over 76 degrees. Turning the cooler down on the machine did nothing to fix it except cause condensation problems in the Laser Drive Modules.

Since the other colors did not seem to be affected we figured it had something to do with the ink. This is when I spoke with an expert in the manufacture of ink and was told that magenta needed more pigment than the other colors and this took away from the amount of body the ink could carry. If you add more of something you have to take something away to get it to fit in a 5 lb ink can.

The bottom line was, we had to keep the room temperature below 74 in order to make the problem go away. This is why the technical specifications of the machine concerning environmental conditions state the room should be not get over 74 F / 23 C.

 

[shaneo1967]

Hi Paul,

The room temp is around the 25 degrees as it has been always. the techno trans temp is 22. the strip is lenght ways and not a tonning problem which i have had before which travels across the page.

cheers

 

[shaneo1967]

hawker,

north qld,

 

[Paul Cavanaugh]

I am curious myself to know what is causing it. Maybe you can post a photo of it next time you see it.

 

[shaneo1967]

strip

strip in pic below

 

[Marc Bremer]

Washfluid drips into the inktrain somehow?

 

[shaneo1967]

i will check marc,,, its always in the same spot

 

[William Taylor]

Looks to me like you have blanket wash dripping from the wash up tube on to your rollers.
If you get a suction bulb and blast the air down the tube when you are close to finishing the wash up then it will help. It only needs a slight drip to cause that mark.

 

[William Taylor]

Sometimes it is the the most obvious of things. It does look like a solvent of some sort coming from somewhere, but have you also checked the forme dampener to see if it has been damaged by something?

Its a DI, its a "waterless" press. There are no damping rollers though I see where you are coming from.

 

[Hawker]

Oh! Thanks

 

[shaneo1967]

Washfluid drips into the inktrain somehow?

i blew the washup line out before the last run. Printed a job of 5000 run and no mark. I think you be right Mark, thanks Paul, hawker and William for your input.

 

[Paul Cavanaugh]

Ding, ding, ding. William gets the prize.

He hit the nail on the head. The wash up tube you are squirting your roller wash solution in is dripping into your ink train while you are running. The machine originally had a special wash-up bottle that came with it which not only automatically metered a small amount of solution into the rollers during the wash up process but also allowed you to blow the tube clear after each squirt of solution.

It turned out the metering cavity of the bottle did not stand up to the solution and quit working. Eventually that bottle was no longer supplied with the press.

The fix is to just blow air through the tube after you wash up. This can be done with an empty wash up bottle if needed.

 

[mightyandy]

I should have thought of that since I've made many a mess with dripping fluid from the washup tubes