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Alcohol free printing
Text writed in collaboration with Prisco®.

Alcohol free printing was first launched in the 1930s in the United States when, under environmental pressure, the legislation required isopropyl alcohol (isopropanol) to be removed from fount solutions. Over the last few years, new European Directives favouring reductions in VOCs (Volatile Organic Compounds) have also encouraged a switch over to alcohol free solutions. However, it is not just the regulatory aspects that are involved in alcohol free printing; it necessarily implies a change in working practices and also represents an incontestable improvement in environmental, economic and qualitative terms.
From the printer’s viewpoint, alcohol offers the following well known advantages:
• It reduces the surface tension
→ better wetting power of the fount solution and therefore better spreading on the non-printing parts of the plate.
• It increases the viscosity of the fount solution
→ better transport of the fount solution towards the plates.
• It has a disinfecting action
→ prevents the formation of algae and moulds.

Nevertheless, alcohol has several major drawbacks and working with it in print shops is increasingly restrictive:
• Rapid evaporation
→ high cost (regular additions required).
• High flammability (flash point 12°C)
→ restrictive storage and use conditions.
• Recognised toxicity limite
→ the European limit for isopropanol (200 ppm) is easily attained in numerous print shops.
• Environmental impact
→ isopropanol is a VOC that participates in the destruction of the ozone layer.
In the course of progressively replacing alcohol based systems, the first generations of products were only “simple” isopropanol substitution solvents. Nowadays, fount solution concentrates are available (even though they are generally known as additives). These are specially formulated products that offer numerous advantages.

In addition to reduced impact on the environment, eliminating alcohol offers considerable operational advantages:

Better print quality: The water / ink balance is obtained more easily and the quality of the emulsion is enhanced, resulting in sharper dots, more radiant colours and shorter drying times.

Reduced toxicity and flammability: The composition of alcohol replacement concentrates meets the directives of the European Agency for Safety and Health at Work (governing body constituted of representatives of the health and safety departments or ministries of each member state of the European Union). Furthermore, the components of such additives have ignition points significantly higher than isopropanol, offering enhanced print shop safety. Certain substitutes (such as the Alkaless type developed by Prisco®) do not have an ignition point.

Lower consumables costs: Although more expensive to purchase initially than alcohol, concentrates are more efficient in use, are employed in lower quantities and involve less redundant usage, resulting in economies. When all is said and done, the use of additives results in considerable savings.

Better control of conductivity: The conductivity has to be as stable as possible on the press to ensure good printing regularity. Conductivity is governed by the ions in solution. However, alcohol does not add any ions and therefore does not increase the conductivity. On the other hand, it can reduce the conductivity through a dilution effect. Additives, concentrated and less volatile, enable the conductivity to be adjusted while at the same time have an insignificant dilution effect.

Good bactericidal action: Fount solution concentrates also include biocides that make up for or even surpass the disinfecting effect of alcohol: this makes it possible to prevent the proliferation of algae, moulds and bacteria in fount solutions.

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