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  • Fountain Solution Conductivity

    Can someone please explain how the conductivity of the fountain solution effects it? What purpose does it serve to measure conductivity?
    Ernie

  • #2
    Re: Fountain Solution Conductivity

    Ernie,

    Conductivity is a measurement for how much fountain concentrate to add to your press water system and monitor the changes during a press run to see how paper, alcohol or sub and ink may be affecting it. Let us say you are using a fountain concentrate that is buffered for Ph, in theory if you add one ounce or 9 ounces of the concentrate the Ph should not change, this is when conductivity comes into play. On your package of plates or your press manual or your ink supplier or your fountain concentrate they may recommend a certain range for Ph and conductivity and the meter will allow you to measure the water bottle to know how many ounces of concentrate to add. Let us say you measure your water source and it is 200uS and your plate vendor says our plates perform better at 1800uS. Add a little at time and measure until you reach the range they recommend. It is a tool to aid you in preparing fountain solution and keeping it consistent. Many big presses use chillers that monitor and change these problems.

    OG

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    • #3
      Re: Fountain Solution Conductivity

      Conductivity is a measurement of electrical flow capability. It has been used for years in the printing industry. With old circulating chemistry conductivity can be 500 to 40,000 and still work properly.
      Conductivity can be a tool to measure but it sure isn't the deciding factor as to wether a fountain solution is too contaminated to work.


      Pat Berger

      Mercer Color

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      • #4
        Re: Fountain Solution Conductivity

        Thanks! I wanted to get a better understanding of what it used for.
        Ernie

        Comment


        • #5
          Re: Fountain Solution Conductivity

          Pat:
          I don't think you have ever run with a conductivity of 40,000, perhaps you exagerate. I think Offset Guy gave Ernie a more useful answer. A typical example that I'm familiar with, the fountain solution is mixed three ounces per gallon of water, and the fresh conductivity is 1800. When the conductivity increases over time, from extracting junk from the paper, the rollers, the ink, the secondary smoke, whatever, when it increases to 2500, the press operators dump the system and make fresh fountain solution again.

          A green solution to this is a technology called FloClear, somewhere down in Texas, but OEM'd by Prisco, where the fountain solution is filtered and recirculated. In this case, the fountain solution can last up to 6 months, so I've heard. Of course it takes a few "green backs" to get this "green solution".

          John Lind
          Cranberry Township, PA
          724-776-4718

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          • #6
            Re: Fountain Solution Conductivity

            Cool! Thanks for the reply.
            Ernie

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            • #7
              Re: Fountain Solution Conductivity

              The last time I dumped my tank was April 2006. I do not have a flo clear because I do not need one. The only thing I am using for filtration are some 20 Micron filters. I have changed them once since April 2006. We print 300 and 350 lpi every day. If I was going to have any trouble it would rear its head with the Hi lpi screening. I would not recommend this unless you have control of your variables.

              Thank you

              Pat Berger
              Mercer Color

              Comment


              • #8
                Re: Fountain Solution Conductivity

                The extremely high reading of conductivity occurred running a job with about 26% coverage of magnetic black ink. The conductivity readings dropped to less than 10,000 in a few days. The point is everything still worked on all presses connected to the central circulator.

                Pat Berger
                Mercer Color

                Comment


                • #9
                  Re: Fountain Solution Conductivity

                  I think most angles have been covered on this already, i think conductivity is a great way to mix your fount solution and if you encounter any problems gives you a chance to check the uS of the tap water pre filteration and post as well as the concentrate, but as a overall indication of efficiency conductivity can be misleading, over here in the cold uk we run aprox 550-600 uS but this soon rises to 1500 within a week or two and this its still ok to run with. It is much easier to use PH as a guide for fount solution efficacy as once you reach a more neutral ph the gum arabic stops desensitizing the plate and you get long startups and poor cleaning of reverse outs.

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                  • #10
                    Re: Fountain Solution Conductivity

                    Just to add to the discussion, few basic points..
                    pH alone cannot help in deciding whether its time to change the fountain solution, because of the +*buffer agent*+ used in it, buffer agent maintains the nature of pH to a pre-determined level even if contaminants from paper and ink are picked up by the fountain solution.
                    Whereas if we talk about the conductivity, then it increases with the increase of contaminants, so conductivity can be considered as a deciding factor.

                    For example, if you start adding small amount of fount to water, the pH will start changing but, only till a certain limit, after that the pH is stabilized by the buffer agent. On the other hand the conductivity will increase with each addition.
                    So pH and conductivity both should be measured simultaneously.

                    Note- Attached file of graph may give some idea about the relation between the two parameters.

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                    • #11
                      Re: Fountain Solution Conductivity

                      you said *magnetic black* so do you mean magnetic ink that used in security printing? please illustrate that because i want some informations about the magnetic ink .

                      best regards

                      Saheb

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                      • #12
                        Re: Fountain Solution Conductivity

                        All that graph shows is the conductivity change when you add fount soloution. Ph is a great indictator of fount quality and a shift from 4.9 to 5.3 has a marked effect as which a change in 500 uS is hardly noticable on press. My point is when a fount soloution reaches PH 5.5 the gum arabic no longer can desensitise the plate and this happens at a specific point, depending on the type of contamination in the fount soloution this point could be at 1500 uS or 3000 uS. Conductivity is a useful tool for repeatable stable chemistry but for an overall guide to the founts efficiency i believe PH gives a more accurate representation, it might not tell you how dirty the fount is but it will tell you how efficient it wil be and thats most important to a press minder.

                        Comment


                        • #13
                          Re: Fountain Solution Conductivity

                          When I ran small offset equipment I don't think that was ever an issue. In larger presses I think back... maybe once a month I had to check for it just to make sure the tap water was up to the demands. This was normally an issue brought up between the ink rep. and whom ever supplied metal plates which between them would come up with a "range" given to said Press Operator(s).

                          Basically keep the water trays clean and prewipe any fresh cut edges with a lint free towel (example C1S) if cutter blade is needing to be changed.

                          Edited by: Atlee Yarrow on Dec 24, 2007 6:27 AM

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                          • #14
                            Re: Fountain Solution Conductivity

                            Magnetic inks have iron or ancor steel or a combination of both powders. These powders are magnetic as well as electrically conductive. When these particles gets into fountain solution they can extremely increase the conductivity of a fountain solution mixture.

                            Pat Berger
                            Mercer Color

                            Edited by: Pat Berger on Dec 26, 2007 6:37 AM

                            Comment


                            • #15
                              [QUOTE=Green Printer;84335]The last time I dumped my tank was April 2006. I do not have a flo clear because I do not need one. The only thing I am using for filtration are some 20 Micron filters. I have changed them once since April 2006. We print 300 and 350 lpi every day. If I was going to have any trouble it would rear its head with the Hi lpi screening. I would not recommend this unless you have control of your variables.

                              Thank you

                              Pat Berger
                              Mercer Color[/QUOTE


                              Wow! More than a year without dumping a fountain solution. The thing that makes this so unbelievable ( I do believe thought) you are only using 20 micron filters. My guess to your success is that a lot of fountain solution is transferring to the paper and vaccuming the pans at the press regularly or something like that. So in reality you are slowly changing your fountain solution. At best a nominal 20 micron filter could delay a change by a week at best and stop some sediment build up in the fountain solution. Also you must be using extra biocides or UV light after two months even with refrigerated circulator.

                              As for conductivity I can come into your plant and completely destroy your fountain solution chemistry without changing your conductivity (it's ability to carry electricity). Conductivity is just a guide to determine how dirty your fountain solution is. What do I start at? and when do dump? but it is not perfect. If you use both pH and conductivity you would have a more accurate guide to determine to dump.

                              Comment

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