Registered in England No. 1725990 Q & A / Advice - Fountain Solutions: Fountain solutions, their formulation and application are becoming increasingly important as a primary method of controlling and maintaining a high level of print quality in the lithographic process. The delicate ink/water balance, walys a precarious relationship between opposing forces, has never been under such scrutiny and, as lithographic presses become more efficient and printing speeds increase, so fountain solutions are required to become ever more sophisticated. Fountain solutions are becoming the key element in modern high speed quality printing. What are the priorities for a modern fountain solution? A modern fountain solution should: o Improve press performance and print quality. o Give clean start-up of non-image areas, eliminate gumming and ensure quick restarts without greasing up or toning. o Give an ink/water balance that is stable during the complete run, both reducing emulsification and ensuring that rollers and plates run cleanly. o Reduce piling of ink and paper dust on long runs. o Keep the fountain circulation components clean. o Improve drying. o Allow maximum ink gloss. o Eliminate or minimise the use of alcohol. o Not corrode plates or press components. o Eliminate any build-up of algae, bacteria or fungus, without formaldehyde or formaldehyde forming materials. o Be used in low dosages. The formulation of fountain solutions should include: o Buffers, to keep the pH of a fountain solution within the specified operating range, regardless of outside influences. o Corrosion inhibitors, to protect press cylinders and other components from corrosion. o Surface active components to modify the behaviour of the water, both to achieve the correct ink/water balance and to eliminate foaming. o Additives, designed to inhibit the growth of fungus, bacteria and algae in the fountain circulation system. o Plate protection agents, to extend plate life and prevent oxidisation. o Components, to prevent the build-up of ink and paper dust. Modern fountain solutions should also be environmentally sound, ideally being free from substances such as formaldehyde or formaldehyde forming agents, chromic acid or other poisons or carcinogens. To know which fountain solution to use, the composition of the dampening water MUST first be analysed. To determine the correct type and formulation of fountain solution the supplier must know: o The composition and hardness of the water to be used in the dampening system. o The design and operation of the dampening system. o The formulation and dilution of alcohol or other fountain solution additives. Water for Fountain Solutions: Selecting the correct fountain solution depends both on the application and the type of water available. Hard or soft water will affect the performance of the dampening solution in different applications. This makes it important to analyse the water, evaluating its hydrogen carbonate content and total hardness, and to repeat this process from time to time. Soft Water: Treating the water to soften it, or to reduce or eliminate the mineral salts, is often seen as a method to guarantee a consistent supply of dampening water. Softening the water by ion exchange, however, is of only limited value and has no effect on the crucial hydrogen carbonate content, which influences the pH value. Indeed, in the case of total mineral salt removal, typically achieved through reverse osmosis, the resulting desalinated water is extremely aggressive towards paper and ink. Additionally, experience shows that both softened and desalinated water, without further treatment, will increase ink emulsification and lead to a rise in dot gain. One method of water treatment which does have considerable value, however, is to cool the dampening water. If the dampening water can be kept at a temperature between 8-12°C then the effect of dissipated machine heat, which results in evaporation and increased water feed and fluctuations in print quality, is reduced. Cooling the water also increases its viscosity, helping to enhance the ink/water balance. Alcohol & Alcohol Replacement: Isopropyl alcohol is generally seen as essential to enhance the ability of the dampening solution to forma an even film across the width of the dampening rollers and around the cylinders; it is traditionally added at a rate of 10-25%. In low alcohol printing, especially in the United States butanol and ethylene glycol are added at a lower rate of 3-5%. The move towards low or non-alcohol printing is being driven both by legislation, requiring printers to reduce and, in some countries, eliminate its use altogether, and by increasing concern over the use of products that can affect working and environmental conditions. Isopropyl alcohol, for example, is increasingly difficult to transport and store and has a strong and unpleasant odour; even water containing a 10% solution has a flash point of only 40°C. As a result, Vegra developed fountain solutions which eliminate the use of alcohol altogether. These conform to the latest health and safety legislation, are considered to be environmentally friendly and also retain and, in some cases surpass, the performance characteristics of traditional alcohol based fountain solutions. Introducing alcohol-free fountain solutions is straightforward; in some cases requiring only minor changes in working practices, in others, being a direct swap for existing products. The increasing rise in the cost of alcohol - and growing concern over the release of VOCs and disposal of waste mean that more and more printers are looking for a proven and costs effective alternative to traditional alcohol based fountain solutions. © Pomeroy Pressroom Products Ltd 2010 Website design by: AH Designs Fount Solutions