Offset printing is an industrial variant of flat print, in which the image is transferred from a flat print form to the printing medium via an intermediate cylinder, which is covered with a blanket. Offset is currently one of the most commonly used printing techniques.
How is ofsset technology used in a printing house?
The offset printing can be split into:
- sheet-fed offset printing – sheet-fed printing substrate, high viscosity offset inks fixed by absorption and polymerisation, and in the case of UV and hybrid inks by ultraviolet-initiated polymerisation,
- web offset web-fed (agricultural) printing – web-fed printing, funnel inks,
- coldset – cold offset: paint fixed by inking into paper,
- heatset – hot offset: paint fixed by inoculating into paper and evaporation at high temperatures (printed ribbon passes through a heat-heated drying tunnel beforefalting).
Coldset and heatset are used for high-volume printing, mainly in newspapers and magazines. The „hot” technique is used in particular for higher quality publications, calendered and chalk paper. Check more: https://printpackpoland.com/
Aqueous offset technique
Aqueous offsetting – until an anhydrous offset occurs, offsetting was always associated with printing using a humidifying solution. In the classic offset, i. e. aqueous, on the flat surface of the printing form there are hydrophilic places, and these wet the aqueous solution, as well as hydrophobic places, and these wet the printing ink. A repulsion occurs between the water-soluble environment and the offset oil paint environment, and it is important to achieve a water-paint balance so that water does not penetrate into the paint and vice versa. This is achieved by appropriate dosing of the amount of ink and water supplied to the printing form.
Moisturizing solution is about 85-95% water. It is supplemented with agents that maintain the appropriate acidity of the moisturising solution (pH-values typically 4.8 to 5.2) and its hardness, as well as with agents that reduce the surface tension of the water, such as isopropyl alcohol (IPA). Some offset machines are not suitable for wetting with IPA liquid. There are also machines that dispense with alcohol humidification in favour of a special buffer solution. There is a tendency to reduce the number of IPA or to abandon it altogether due to its harmful effects on the environment and employees. This trend will intensify, forcing the use of appropriate buffers.