Offset ink is a pasty material composed of following: 

1. Pigment which actually constitutes the color of ink.

2. Resine which gives pigment adhesion to the pigment.  

3. Carrier, which plays the role of lubricant and pigment transfer on the printed material. It is usually an oil-based material. 

4. Additives that are added to the ink for better printing performance, including to help quicker drying.

In offset systems, the ink should be transferred from the plate on the cylinder and then on paper. During this transfer, its thickness decreases, the ink must have a high coloring power, so the higher the amount of pigment inside the ink, the greater the coloring power of the final layer transmitted on the paper. It should have fluid properties, so there should be some fluid in the compound so that the pigments move in.

Offset printing ink should have a high density and should not be mixed with water. Increasing the ambient temperature and ink stirring due to the rotation of offset printing machine rollers reduces the compound concentration, while the compound stirring increases its adhesion.

Inking Rollers

In order to achieve the proper quality in offset printing, regular and high-resolution rollers  seems to be necessary because a very delicate ink membrane is needed for the image areas  on the plate.

Suitable Chemicals

In the ink structure, it should not be any chemicals which causes corrosion on rubber rolls, and the solvent should not absorb rubber rollers. 

Chemicals used in ink structure should not cause corrosion in metal rollers.

When working with ink, be careful that: 

- Good ink has good transparency and coverage and better contrast  . 

- Good ink should dry early. The operator should not increase the ink rate for more coverage and higher density power.

- When using high quality ink, the required color can be reached with the lowest amount and it is not necessary to remove a large volume of inks, in which case the operator does not have to change the pallet board early. 

- A good ink achieves a better balance with water. In this case, the volume of water and compound is minimized.

- To achieve the desired color, the ink should not be too high. This causes many other problems.