ink on water pan rollers

[mazengh]

We just made the switch to ipa free fountain solution which is one step. we changed our water pan rollers and the dampening form rollers. We can print clean with acceptable water levels between 45 and 60(used to be a lot less with 10% ipa). the only problem is that the water pan rollers are picking alot of ink which never happened when we used to run ipa with 2% fountain solution. note that our fountain percentage now is at 4% and we tried different fountain. all the same result.

 

[turbotom1052]

what kind of press? Have you tried to desensitize the chrome roller? I make it a point to desensitize the chrome rollers at least once a week.

 

[RGPW17100]

I have never had to desensitize my rollers and have been running sub now for over three years. Your issue may be that the cleaning effects of the alcohol are no longer there and may require a preliminary desensitize. I would use printers pumice and a soft lint free damp rag. Go over the entire roller then rub it clean of the powder with another rag using fountain solution and another clean rag. Once the new fountain takes it should not take on ink. Then again I am basing this on a alcolor system. You clean it every night with MRC and there should be no issues. If you are using a different system like Kompac, Crestline or dalgren you may need to gum the chrome roller each night. What damp system are you using?

 

[duct maestro]

You need to get your ink/water balance correct. I used to find that on my sheetfed if I took over from another shift I'd have this problem! Gradually bringing my water and ink down prevents it from coming back it's emulsified ink. I just think you've got a smaller window with which to work. Expect a slight fur from your inks under the eye glass but make sure it's within tolerance

 

[duct maestro]

I have never had to desensitize my rollers and have been running sub now for over three years. Your issue may be that the cleaning effects of the alcohol are no longer there and may require a preliminary desensitize. I would use printers pumice and a soft lint free damp rag. Go over the entire roller then rub it clean of the powder with another rag using fountain solution and another clean rag. Once the new fountain takes it should not take on ink. Then again I am basing this on a alcolor system. You clean it every night with MRC and there should be no issues. If you are using a different system like Kompac, Crestline or dalgren you may need to gum the chrome roller each night. What damp system are you using?

Silvo works a treat! For desensitisation

 

[Coastline]

As said above, you need to desensitise the dampening rollers: https://www.box.com/s/fb329ba59c75825cc82b

For attaining the correct ink/water balance:

The following steps should be used as a guide on setting the proper ink and water balance on your press:
INK & WATER SYSTEMS - cleaned and maintained to press specification
FOUNTAIN SOLUTION - measure proper conductivity
ADJUSTMENTS - reduce water first, then ink and repeat this sequence
1. At the unit reduce water level 5 points at a time. Allow 3 to 5 minutes for the press to react.
2. Observe ink level and reduce as necessary to maintain proper density.
3. Continue this process until you reach the minimum water settings. Minimum settings are when the background looks dirty and the ink density is in specification or slightly below.
4. If you get toning in background, bring water level up slightly.
5. Once water settings are correct, proceed to adjust ink to proper density. Check with a densitometer, do not guess.

 

[mazengh]

Thank you everyone for your support. desensitizing definitely helped but didn't solve it completely. We had to increase the dampening temperature from 10 degrees celcius to 14. With alcohol it used to be 10.

 

[Sustainable]

a. you have too much ink in the roller train for the image
you are printing

b. your water cooled in oscillators are too cold

c. your fountain solution is too cold

d. you have too much cobalt and maganese in your sheet
feed inks (and/or too low a boiling rate solvent in the ink)

e. your chrome rollers need to be cleaned and desensitized


f. All of the above

 

[Coastline]

Thank you everyone for your support. desensitizing definitely helped but didn't solve it completely. We had to increase the dampening temperature from 10 degrees celcius to 14. With alcohol it used to be 10.

We usually recommend a temperature of 12oC, as it helps reduce the shock-effect of the colder water coming into contact with the warmer ink.
If 14 works for you, then that's fine; glad to hear you've got an improvement.