Dampening solution analysis
Dampening solution analysis
The dampening solution is the third important variable for offset printing, along with the printing plate and the offset ink. The optimum interaction of these system components results in perfect printing results even over long runs.
The 4 main functions
The functions of the individual substances can be grouped into four main groups:
I. Buffer components ensure a stable pH value in the dampening solution
II. plate protection components remain on the water-bearing layer after the printing plate has dried and facilitate rapid remoistening
III. Wetting agents adjust the surface tension of the dampening solution and guarantee uniform wetting with low water consumption.
IV. Solubilizers ensure that the wetting agents are miscible with the water.
and a sufficient shelf life of the dampening solution concentrate is given.
The basis: The water
The water occurring in nature is not pure, but contains numerous gases and minerals. For the printer, tap water is the raw material for his dampening solution. The water hardness is measured to assess the water hardness, which essentially depends on the calcium and magnesium content.
The water hardness must always be determined before additives are added. This is because the hardness of the finished dampening solution can no longer be determined by simple means. Test strips help to determine the total hardness easily. The determination of the carbonate hardness is carried out with an indicator solution (measuring aids are available from Gebrüder Heyl, Myron L, Merck, Neukum …). It should be taken into account that a measurement is always a “snapshot” and the water quality can vary greatly.
An exact water analysis can be made on request.
Request the IPM fencing solution guide now and get a general overview of the dampening solution, its composition and its use in the printing industry.
Frequent printing problems due to incorrect dampening solution settings
1. mounting on the blanket:
Attack on the paper coating by acidic dampening solution
Coatings on the rollers, blanket and plate
3. plate wear:
Printing layer is destroyed. Additives too aggressive, wrong machine setting
4. plate corrosion:
Plate oxidized, plate protection insufficient due to additive
pH-value too high, too much water, water too soft, additive too high, roller adjustment wrong, too much IPA, little ink removal
6. bad drying:
PH value too low, wrong substrate, ink combination, substrate pH value too low
7. Bad freewheeling:
PH value too high, IPA too low, plate protection inadequate, roller adjustment incorrect, ink, dampening solution balance is not correct
Too little dampening solution, dampening solution unsuitable, contaminated, wrong machine setting
Overemulate, wrong ink, dampening solution balance
pH value too high, plate protection inadequate, plate poorly developed, ink guidance too high, deposits on plate or blanket, IPA too low, ink/ fount solution balance incorrect, temperature incorrect.
11. Incoming dampening solution drifters:
Too few hydrophilic substances in the dampening solution, chrome accepts the ink.
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