Desensitising steels on GTO

Discussion in 'Heidelberg Printing Presses' started by Travis Young, Feb 23, 2020.

  1. Travis Young

    Travis Young Member

    Joined:
    Oct 2019
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    66
    Location:
    Victoria Australia
    My dampening steel rollers are all picking up lots of ink making it a bit hard to maintain ink/water balance. In the past I've always cleaned them with gum washout and left a little coating on them every night and never had too much trouble.
    Anyone know of any desensitising chemical available or any little trick?
    I'm also wondering if my fountain solution may be contributing but I have no issues with emulsification in the ink train or scumming so I don't know.
     
  2. MacD

    MacD Member

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    Nov 2016
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    Location:
    USA
    I would probably target fountain solution at this time. Test the pH and conductivity. Using a one or two-step solution?

    I have used several desensitizing agents on the roller and haven’t noticed much difference. I have used allied pressman products, Heidelberg consumables, Prisco products over the years.

    Before changing anything I would check roller settings and roller and dampening temp levels. Also, if you are using a roller preserver, or a deep cleaning agent, would make sure residual product isn’t desensitizing the water train. Guessing you have done all this since you wouldn’t bring your problem here if it were something that simple.
     
  3. Travis Young

    Travis Young Member

    Joined:
    Oct 2019
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    66
    Location:
    Victoria Australia
    Thanks for your reply.
    No no roller settings are all good. Very easy machine to set.
    I would think it pretty unlikely to be anything to do with temperatures as it happens on any size run length and GTOs don't really run fast enough to heat too much up (not mine anyway!)
    I use a bit of Poropast every now and again to clean and deglaze but I normally tap up some yellow afterwards and wash that straight off as well.
    What you say about desensitising agents rings true.
    I haven't tested the ph levels but logically it probably is related to the fountain solution. Seems obvious once you think about it. Thank you for allowing me to think out aloud!
     

  4. SM52

    SM52 New Member

    Joined:
    May 2012
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    3
    Location:
    Utah
    Clean off roller with press wash to remove ink, then clean with ajax cleaner(ajax cleaner will remove oil and solvent from roller) and for the last step coat with full strength fountain solution.