Conductivity

[pacificiam]

Wat is d Ideal conductivity of Sheet-feb press?

Hw to find out / decide the conductivity of the press?

 

[mazengh]

i believe conductivity should start between 1000 and 1500 microsiemens then as it gets dirty with time while printing it rises.... once it's 1000 microsiemens over what it started then it needs to be replaced...

 

[REYES1377]

It really depends what you are useing. One step or two step, also what the manufactorers recomended doseage is. But generally in should be between 1800 and 2000, in my opinon

 

[shajith]

The best conductivity of mixed solution is between 1200 to 2000 , above 1800 its advisable to change the water.
conductivity of the mixed fountain solution depends on the fresh water conductivity and the amount of fountain chemical mixed. also please note that the conductivity reduces with the increase in percentage of alcohol in the soultion

Since approximately 98% of a working fountain solution is water, being aware of your water condition is of vital importance.
Water can be either hard or soft, acid or alkaline. In fact, water quality can vary seasonally, monthly, weekly, or even daily. Understand that tap water can be a variable.
when used in fountain solution because some minerals and chemicals in the water may not be compatible with the chemicals in the fountain solution concentrate.

Water hardness is rated in terms of total concentration of calcium carbonate ions. Water hardness usually is indicated in parts per million (PPM) (or milligrams pre liter (mg/l) or grains/gallon) of calcium carbonate.
Water hardness can be estimated by using a conductivity meter.

Water used for printing must be medium hardness

Water Hardness Table
Degree of Hardness Grains/GAL MG/L
Or PPM Conductivity
MICROMHOS/CM
Soft 0 -7.9 0 - 135 0 – 225
Medium 8.0 15.9 136 - 272 226 – 450
Hard 16.0 > 273 > 451>

In areas with alkaline water, alkalinity is more important than water hardness because excessive levels shift pH towards neutral.

my method of finding the correct mix of fountain and water is as follows.
measure the conductivity and ph of fresh water ( example conductivity 500 and ph 7)
then mix 1 % of fountain chemical and note the same ( example conductivity 800 and ph 6)
add another 1 % of fountain chemical and note the same ( example conductivity 1000 and ph 5.2)
add anothe 0.5 % of fountain and again note the values ( example conductivity 1200 and ph 4.7)
on further addition of fountain if i notice that the ph remains the same and conductivity is increasing then i set 2.5 % as my fountain chemical dosing percentage . i will see a further reduction in my conductivity when i mix alcohol of 9 %.

hope this was of some help

regards
shajith

 

[mazengh]

RO

RO

what if water is coming out of an Reverse Osmosis system with a very low conductivity.... can someone use a fountain solution that is made for soft water? for example if you check the bottcher fountain solutions, they have a product that would increase the conductivity by 775 µS/cm per 1% of fountain.

here's the link below

http://www.boettcher.de/PDF-Dateien_engl/Chem/FM/S-3021_engl.pdf

 

[shajith]

ideally very softwater is also not good for printing, we set the water such that even after RO the water will have a conductivity of 300 to 400.

 

[mazengh]

how do you set water conductivity to be 300 to 400 after RO treatment? do you just change the level of how efficient the RO will be? also what if the fountain solution is increasing the conductivity? does it still require that the RO water conductivity be set to something? and does that mean that with the added conductivity the water hardness will increase?

 

[Bloodsaler]

The ideal condition depend on what kind of foutain you use.The nonalcohol one ofter got very low conductivity,and some alcohol foutain also got strange conductivity.One of foutain we use have this strange issue.During the using,the conductivity not vary much from the beginning to the end,but PH value will go higher and higher.Usually,the beginning conductivity should around 1000us/cm，and when the conductivity 800-1000us/cm higher from the beginning,you have to think about clean the dampen system,
One usual way is let your operater clean the dampen system every week,so this will ensure your water in a regular condition,and it`s very important for the process control too.