Ink drying in sheet-fed • Physical part (ink absorption, ink setting ) • Goal is to have enough setting that ink would not set-off in the delivery pile • Chemical Part (oxidation) • Oxidation of ink binder • Oxidative drying lasts for several hours depending on the type of ink and properties of the substrates • Drying agents (siccatives) will accelerate the drying process.
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Ink drying in sheet-fed
• Physical part (ink absorption, ink setting )
• Goal is to have enough setting that ink would not set-off in the
delivery pile
• Chemical Part (oxidation)
• Oxidation of ink binder
• Oxidative drying lasts for several hours depending on the type
of ink and properties of the substrates
• Drying agents (siccatives) will accelerate the drying process.
Spray powder
• Spray is used to avoid ink set-off
• Spray powder is the distance holder between the sheets.
• It increases the amount of oxygen to improve the oxidative drying process.
• Spray
• 10 to 80 microns
• calcium carbonate
• organic, vegetable based powder of natural
starch
Drying problems - sheet-fed
• Inadequate drying
• Similar smearing as in heatset if ink layer not dry enough
• Silk grades
• same problems but sheet-fed inks a bit better than heatset inks