conductivity

Discussion in '4-Color Offset Presses +' started by aqazi81, Apr 26, 2012.

  1. aqazi81

    aqazi81 Senior Member

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    What's the ideal conductivity of the water and when should we replace?
     
  2. OkiTech

    OkiTech Senior Member

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    1000 to 1200 over the conductivity of water, I think.
    You must check that before adding an alcohol, that is if you use it
     
  3. aqazi81

    aqazi81 Senior Member

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    our tap water has a conductivity of around 1350.... so how can i decrease it?
     
  4. Komory

    Komory Member

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    Too much minerals in the water.
    Need to use a filtels or RO system.
     
  5. FSA

    FSA Senior Member

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    Most of my water tanks have conductivity meters in them, with a fresh mix we hit 2500 , as soon as we start to pound the work through the number starts to increase. At 4350 if not paying attention we start to get dot slur. At 4800 plus the water sweep has doubled and it is not easy to print clean, but still prints. If time is pushing , drop half the tank and top up the conductivity usually drops back down to 3000-3200, and back in production. Running metal CTP with water straight out of the tap, using Prisco 2451 plus 2 etch. 200 line shop standard, on an 102-8c-p, mov p with alcolour, and both ryobi 3304H. Conductivity is a guide line, a press with good rollers set proper and an operator that understand printing can achive good results and not care about were the conductivity is.Good rule of thumb is, the fountion solution looks like crap and full of *@#? change it !
    FSA
     
  6. William Taylor

    William Taylor Senior Member

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    It should state what the conductivity after water should be on the fount bottle.
    Measure the water first and then add the relevant amount of fount/sub/alcohol, whatever you use. For example if your tap water is 200 and fount should be 1000 over the tap then a good conductivity is 1200. If it starts getting 600-800 over then it would be good to change it or add some fresh.
    I find that it is more critical using an alcohol sub as opposed to alcohol and so have to keep a closer eye on it.
     
  7. turbotom1052

    turbotom1052 Senior Member

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    Wow!!! i don't know that I've ever mixed fountain solution starting with tap water with a conductivity as high as 1350. You sure your guys aren't pissing in the water supply??? You can get the conductivity down to Zero with a good reverse osmosis filtration system. If you were to start at 0 i would add solution to bring it up to app. 1000 or so. If you run alcohol the alcohol goes in after you've arrived at the 1000 with just the fountain solution. Once you add alcohol you will see the 1000 drop a couple of hundred depending on how much alcohol and how pure. As long as you water roller durometers are reasonably soft I'm thinking that you shouldn't need more than 5% alcohol on a Heidelberg.
     
  8. aqazi81

    aqazi81 Senior Member

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    I'm sure you wont be surprised to know that its our drinking water.... and we are still alive.... ;-)
     

  9. TECHNER

    TECHNER New Member

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    Hello

    The correct value of water conductivity , in offset application, is 600-800 µs .
    Then this water is mixed with additive + alcohol to increase around 1200 µs ( then this conductivity will increase because of pollution by ink, paper ...)

    The most important component of offset process is water , so the best way to control this parameter is the OSMOSIS UNIT .
    But be careful only osmosis treatment is dangerous as the water should not be pure 0 µS ! remineralization is necessary ...

    Don't hesitate to contact me for explainations or a quote :

    www.techner-solutions.com
    phone /whatsapp : 0033 6 52 46 71 00
     
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