Myron L Litho-Kit User Manual

YOUR

LITHO-KIT

GUIDE

™

Conductivity (micromhos/cm)

pH

pH

Conductivity

Concentration (oz./gal.)

3500

3000

2500

2000

1500

1000

500

0 1 2 3 4 5 6 7 8

7

6

5

4

3

2

1

INTRODUCTION

Your Litho-Kit™ is a quality control "tool" to help you
print better. It and this Guide will improve your printing
through better control of fountain (dampening) solutions.
The rising popularity of alcohol-free solutions has
increased the need for very careful monitoring of their
conductivity, pH and temperature.

While this Guide offers information we hope will be very

useful, it makes no specic recommendations regarding

fountain solution temperature, concentration, pH or
conductivity values. A good source for such information
is your solution supplier, who is most familiar with
your local conditions. Another source is the Graphic

Arts Technical Foundation, a non-prot research and

educational organization which provided much of the
information in this Guide.

CONDUCTIVITY AND pH: HOW THEY CAN
HELP YOU

The Myron L instrument which is the "heart" of your kit
is either a conductivity instrument or a conductivity/pH
instrument. Both are industrial-quality instruments for
professionals. Reliable even in demanding conditions, they
feature electrodes mounted inside a cell cup for maximum

protection. Details of specications and operation can be

found in the instruction manual in each kit.

Conductivity is the ability of a solution to pass an
electrical current. The amount of current passed
depends on the concentration of ions, or electrically
charged particles in the solution. The higher the
concentration of ions, the higher the degree of
conductivity. The unit of conductivity measurement is the
microsiemen (also called the micromho).

Traditionally, pH, a measure of the degree of acidity
or alkalinity, was used to check fountain solution
concentration. Today, however, conductivity testing
is recognized as a much more accurate method.
Many modern dampening solutions are pH stabilized
(or buffered), so only small changes in pH are seen,
even when solution strength is dramatically changed.

The conductivity, however, increases as solution
concentration rises.

The advantage of checking fountain solution
concentration with conductivity, rather than pH, can be
seen in the following graph.

Concentration vs. pH and Conductivity for a hypothetical
combination of fountain solution concentrate and water

Notice how the pH levels off, but conductivity values rise
on a straight-line basis as the concentration increases.
This "linear" relationship allows you to easily match the

conductivity value to a specic concentration of your

own solution.

Even though pH usually is not the best method to check
the concentration of fountain solution, it is still very
important and must be checked regularly. The pH of acid
dampening solution affects sensitivity, plate-life, ink­drying, etc. Also, pH can change during a run if the paper
has a high acid or alkaline content. Conclusion: pH must
be maintained at the proper level for good printing.

The table below lists recommendations for checking
fountain solution conductivity and pH.

RECOMMENDED TESTING METHOD

TYPE OF FOUNTAIN SOLUTION

ACID X X X X

BUFFERED ACID X X X

NEUTRAL X X X

ALKALINE X X X

MIXING ON PRESS

COND. pH COND. pH