Chemical Breakdown:

Today, fountain solutions are complex formulations. Occasionally we are asked to determine if there is a compatibility problem between the chemistry of the fountain solution, and the inks and/or coatings that are used on a job. Or, a pressroom may want to change solutions, so we check the new formula to assure compatibility. And finally running a complete chemical breakdown can also check batch-to-batch variations.

Here is a typical project including the type of tests run and a sample breakdown.

Sample Identification: One (1) sample of "ABC" Fountain Solution.

Project Description: To perform a chemical analysis on the Fountain Solution Concentrate.

Method of Tests:

  1. Gas Chromatography-Mass Spectroscopy Analysis.
  2. Vacuum Distillation followed by Fourier Transform Infrared Spectroscopy Analysis utilizing Computer Library Matching.
  3. Solvent Extraction and Solid Probe Mass Spectrometry Analysis.
  4. High Pressure Liquid Chromatography Analysis.

Results:

Chemical Component Approximate Conc.,
% by Weight
Malic Acid 3.0  
Carboxylic Acids 2.5  
Propylene Glycol 8.5  
Ethylene Glycol 2.5  
Butyl Carbitol 11.5  
Carboxymethyl Cellulose Derivative (CMC) 7.5 (gum substitute)
Polyoxyethylene-Polypropylene-Polyester Surfactant 3.5  
Isothiazoline Preservative 0.1  
Ammonium Nitrate 2.5  
Water 58.4  

pH and Conductivity:

"In the old days" when fountain solutions were hand mixtures of WATER, ACID, and GUM ARABIC, pH was easily used to monitor how concentrated the solution was, which measured the acid present.

Now, formulas are highly buffered, which means the reading on a pH meter does not respond to changes in the concentration of the mixed solution. That is, as more concentrate is added to the tank, pH will not change. So, both over and under mixing can result.

Conductivity (see photo) is a more accurate determination of the concentrate level in a mixed fresh solution. Electrical conductivity responds to the level of acid and other metals in the solution

pH and Conductivity curves are run on a concentrate sample (using the water source from the pressroom) to determine:

  • The pH range of the mixed solution at various concentrations
  • The level of buffering
  • The target starting conductivity value for the pressroom

Complete details on fountain solutions are contained in the Technical Notes Article "Facts about Fountain Solutions", and "pH and Conductivity".