Contuctivity of dampening solution

[Raman karthi]

Dear respected senior members.

I have problem that I'm running 4 color machine. And when I changing dampening solution.

Starting conductivity is coming more than 1500 point.plese explain about the history of dampening solution.

Thanks

 

[turbotom1052]

My suggestion would be to measure your tap waters conductivity without any other additives. This is where I say that reverse osmosis water will be your best starting point. Ive seen water out of the tap vary wildly. Then you will want to mix in your fount as per the manufacturers suggestions. I would strongly discourage a 1 part solution where the alcohol sub is already mixed in. Once you're mixed to the manufactures suggestion you will want to read PH just to be sure you're within range. Then read conductivity of the mixed solution and note the reading. You will want to keep the running conductivity within 1000 to 1100 of your starting point. When you see yourself exceeding 1100 over your starting point it's time to either drain some off and replenish with fresh solution, or drain the entire tank and start fresh. I would strongly discourage you from just tossing in isopropyl alcohol unless its just to get your through the rest of a shift and even then be cautious.

 

[Raman karthi]

Thanks for the information, and please can you give me the details, what is conductivity and what is hardness and ph level. What is range is good for printing and what is problem will come if the renge are changing and how to mix up the solution to get proper range.

Thanks.

 

[turbotom1052]

There are many details and papers written and available online that can give much more info than I could offer, but in a nutshell..... Conductivity is the ability of a liquid to flow electricity.. The higher the total dissolved solids (TDS) in a liquid, the greater its capacity to flow current. The measurement is expressed in uS/cm. This measurement is as close as I can come with the characters that are available on my keyboard. As the fountain solution gets contaminated during a press run its conductivity will rise. There are many solids that will leach into the fountain solution from the paper and ink, and even to a lesser degree the atmosphere in the pressroom. I mentioned using reverse osmosis water as the best "starting point" for your fountain solution mix mainly because of its consistency. Following reverse osmosis treatment, water will not only have a very low conductivity but also a very repeatable conductivity. Ive seen tap water with not only high conductivity but of greater importance hugely varying conductivity based upon many factors throughout even the course of a day!!! So to be able to measure conductivity is to be able to measure from a known starting point your fountain solutions level of contamination. Conductivity and hardness are pretty much interchangeable. PH is a measurement of acidity or alkalinity on a scale where 7 would be right in the center of the scale. Many years ago it was PH that was the go to measurement for how we would measure our fountain solutions condition. This measurement is not nearly as important these days, as fountain solution manufacturers have found ways to make their product much more stable and resistant to fluctuation. As far as the range of conductivity for good printing as I mentioned 1000 to 1100 uS/cm above the measurement of your mixed fountain solutions starting point. For example if you start with reverse osmosis water that measure 5 right after treatment, and mix to your fountain solutions manufacturers recommended dosing to come up with a ready to run solution of lets say 200 uS/cm ,then you will want to try and keep the conductivitity from exceeding 1350uS/cm. This would be in a perfect world and in reality a single shift of operation could have you close to that limit considering the crap thats available to print on these days. The good news is that as you run the press, the fountain solution gets depleted and replenished allowing for a reduction in conductivity.