In offset printing, it is imperative to consider printability as a function of
the paper quality.
• Non coated : The most suitable inks are not very siccative. Drying mainly occurs through absorption (macroporous substrate) and is completed through air oxidation of the vegetable oils in the ink.
• Matt coated : These substrates have good absorption characteristics but a rough surface. The deposited ink film must be more abrasion resistant and therefore have a hard surface. Siccative inks are the most suited for printing on this type of substrate.
• Gloss coated : The inks used can be overnight, semi-overnight or siccative, and mineral or vegetable based.
The choice depends on the quality of the coating and may necessitate a test beforehand.
In the same way as gloss coated paper, the choice of ink is made as a function of the quality of the cardboard. Since printing on cardboard is generally followed by a post-printing treatment (varnishing, laminating, etc.), it is indispensable to check the aptitude of the ink film to undergo this treatment.
Synthetic and non-absorbent substrates
These substrates are non-porous or very slightly micro-porous. In order to obtain good ink adhesion, it is essential to use very siccative inks. In the case of synthetic substrates, the required surface energy must be at least 38 dynes/cm.
Metallised and metallic substrates
Specific ink formulations are used for printing on metal. Their principal characteristics
are good adhesion to the substrate and good film flexibility properties so that they can undergo bending, stamping operations, etc.