Fountain solution additives: why offset printing is not all about inks
It’s not all about inks – even at hubergroup Print Solutions. In offset printing, for example, fountain solutions play an important role alongside inks as they make flawless offset printing possible in the first place. hubergroup has been a pioneer for fountain solution additives since offset printing has established itself as a printing process and, since then, we have worked continuously to improve the quality and environmental standards of our products. However, fountain solution additives often do not receive the attention they deserve. We have therefore asked some of our experts for fountain solution additives to tell us a few basics about the role of this printing component in offset printing.
Why are fountain solution additives important at all?
Frédéric Kocher, Head of Product Development Fount: "Offset printing is the only printing process that uses two different liquids on the same printing plate – inks and fountain solutions. The viscous ink is – and is supposed to be – visible after the printing process, while the fountain solution is solely apparent in the print image if something has gone wrong. So, the fountain solution only seems to be important when things are not going well. However, only the perfect symbiosis of both components facilitates the desired separation of image and non-image areas and thus high-quality offset printing. The fountain solutions must, therefore, also be constantly adapted to the changing requirements of offset printings, such as the increasing demand for quality, improvements in printing technology and the ever-increasing printing speed. This is where fountain solution additives come into play."
What are the functions of fountain solution additives?
Matthias Otto, Technical Sales Packaging: "Fountain solution additives have a whole range of functions. Relating to the water used, the fountain solutions additives ensure high-quality printing by stabilizing the pH, setting the surface tension, and partially binding the hardness materials. With regard to the printing press, they allow the adaption to various types of dampening systems, protect the steel parts, rollers, and plastics of the machine and ensure optimum productivity. Additionally, fountain solution additives have an impact on the printing plates: They ensure good wetting of the non-image areas as well as a fast plate cleaning and provide good corrosion protection for the plates. As far as the substrate is concerned, the fountain solution additives make sure that the paper coating does not dissolve and that there is no separating layer that could negatively affect the ink adhesion. Last but not least, there are, of course, inks: Fountain solution additives are responsible for a stable ink-water emulsion as well as a fast adjustment of the ink-water balance and they should not deteriorate the drying characteristics of the inks."
When is water treatment necessary for offset printing?
Simone Esser, Product Development Chemist: "Since water quality plays an important role in offset printing, water treatment is always necessary when conditions vary. This is the case when the water comes from different sources with varying total hardness or hydrogen carbonate concentrations or when the water quality fluctuates strongly depending on the season. Additionally, the water should be treated if one of the following conditions applies:
- the process water is very hard (more than 15–18°d) or very soft (< 7°d)
- the process water contains salts that might interfere in the printing process (iron, corrosive ions chloride, sulphate, nitrate)
- the conductivity is more than 500 µS/cm
- the conductivity fluctuates by more than 200 µS/cm."
What other factors relating to fountain solutions should printers consider in the printing process?
Reiner Schnittger, Technical Sales / Web Offset Printing: "Further key factors in offset printing are the temperature of the fountain solution, the alcohol concentration, and the correct amount of the fountain solution additive.
The fountain solution temperature should be at about 10°C ± 2°C or about 10°C below room temperature as a higher temperature can cause problems such as ink feed-back into the fountain solution, partial ink build-up on the chromium rollers, an increased fountain solution transport resulting in lower full tone density, an increased IPA [isopropanol] consumption, reduced fountain solution viscosity or microorganism growth.
Alcohol influences the cooling, the surface tension, the viscosity, and the ink-water balance. Consequently, a too high or too low alcohol concentration can increase the waste rate and thereby also the costs and create an unstable ink-water balance, over-emulsion as well as a poor clean-running of the plates. Printers should, therefore, strictly adhere to the alcohol concentration recommendations of the manufacturer of the fountain solution additives.
Also, concerning fountain solution additives printers should respect the recommended dosage as the wrong amount of fountain solution additives influences the pH value, the buffer capacity, the plate protection, the wetting properties, the corrosion protection, the viscosity, the emulsification, the ink-water balance, and the drying time."
What do printers need to consider when choosing a fountain solution additive?
Rogerio Gomes da Silva, Technical Service Manager Sheet-Fed: "To choose the right fount solution additive, the water quality, the alcohol concentration, the printing process (sheet-fed or web offset), the press, the dampening system, and the substrate (absorbent or non-absorbent) need to be taken into account. Of course, we will be happy to assist you with that."
Are you looking for more insights into fountain solutions?
Find all information here or simply ask our experts:
Europe: Web Offset
Rogerio Gomes da Silva