From: Gary Jones (firstname.lastname@example.org )
Date: Mon, 31 Mar 2003 09:10:37
Fountain solution is a mixture of water and other volatile and non-volatile chemicals and additives that maintains the quality of the printing plate and reduces the surface tension of the water so that it spreads easily across the printing plate surface. The fountain solution wets the nonimage area so that the ink is maintained within the image areas. Non-volatile additives include mineral salts and hydrophilic gums.
There are three principal types of fountain solution, acid, neutral, and alkaline. In commercial printing (i.e. sheetfed and heatset web), phosphoric acid is use to maintain a relatively low pH. In addition, commercial printers will use alcohol and alcohol substitutes, including isopropyl alcohol, glycol ethers, and ethylene glycol, are the most common VOC additives used to reduce the surface tension of the fountain solution.
Wetting additives are not generally used in newspaper and nonheatset web printing. Although, ethylene glycol can be used as an anti-piling agent to keep paper debris from accumulating on the blanket.
It is quite difficult to predict how often a printer will change their fountain solution. There are many factors that influence the frequency and they depend upon the quality of the incoming water, impact that the ink and paper is having on the fountain solution chemistry itself, the type of press (e.g., duplicator Vs true sheeted press), and/or the use of recirculating systems with filtration. Some printers find that they do not have to change fountain solution at all because it is consumed during printing. Other printers may have to change the fountain solution frequently due to the problems associated with the items identified above.
The question as to the classification of fountain solution as a "dangerous waste" depends upon the definition of what constitutes dangerous. In the US, waste fountain solution is not generally classified as a hazardous waste. This means that it does not require special handling and disposal is usually accomplished by discharging to the local sewer authority. If the printer is using a lot of alcohol (15-25%), then discharge to the sewer is generally prohibited due to the low flashpoint.