Virtually all types of promotional pens carry an advertising message or promotional logo but the printing inks used on them can vary enormously, depending upon the material the pen is made from and the printing process being utilised. Here, you will find an overview of the printing inks in most popular use.

Solvent Evaporation Inks: These are without doubt the most common inks used on plastic promotional pens. The term does not apply to any particular ink but is a large family of ink systems formulated for their intended purpose. Solvent evaporation ink systems are optimised for printing on paper & board, touch control panels, overhead projection slides, as well as for promotional pens and many other promotional items. Although their chemistry is diverse, the mechanism for drying is the same; through the evaporation of solvents within the ink. These ink systems can be made up of sixty percent solvent which has to evaporate after the ink is printed. Therefore, it follows that the volume of a solvent evaporation inks decreases by that amount when dried and that is why these inks are regarded as low-build or low-feel inks. These inks when printed on promotional pens achieve a high level of adhesion because the active solvents melt the plastic. This results in a strong bond being created between the ink and the pen substrate and normally this cannot be scratched off. Typically, plastic promotional pens are made from ABS, styrene or acrylic and solvent evaporation inks are perfectly suited to printing these polymers.

Catalyst Inks: These inks are used on promotional pens when the material the pen is made from is impervious to solvent attack. In this case, the bonding mechanism relies on the ink sticking to the pen like glue and there is not chemical bonding between the ink and the substrate, unlike solvent evaporation inks. Again, the term 'catalytic' refers to a large family of inks optimised for different materials and applications. Within that family will be inks to print polypropylene, metal, stove enamel, nylon, glass, wood etc. They all have one thing in common, however, and that is their curing mechanism relies on the polymer chains cross linking with each other which is initiated by the catalyst or hardener that is added to these inks. Although these inks carry solvents, they are not usually aggressive because their presence is to make the ink into a printing consistency and not to achieve adhesion. Generally, catalytic inks have a high-build when printed because they have a high solids content.

U.V. Inks: These ultraviolet curing inks, are being increasingly used in the screen-printing industry for printing promotional pens and promotional items in general. They are similar to catalytic inks in that they require an additive to be added to act as a catalyst to initiate cross-linking. This catalyst is referred to as photo initiator. Their main advantage is that they are quite easy to print because they do not dry in the screen. This is referred to as good screen stability and it normally means downtime is reduced. Other benefits of UV curing inks are, finer detail can be printed, higher gloss levels and better print definition. The disadvantages are that they can be quite translucent compared to other ink systems, they have a high build, they are quite brittle, ink-adhesion is more temperamental, high degree of brittleness, they produce ozone when cured and a protective gloves must be worn to handle them. Normally these inks are used to print promotional pens made of ABS or styrene, but it is also now occasionally used for metal pens and pens made from polypropylene.

Long Oil or Oxidation Inks: These inks are hardly ever used these days but are sometimes used for printing on materials when other systems will not provide adequate adhesion. They resemble paint in their drying characteristics in that they require the presence of oxygen to dry properly and they take days to become completely hard. They are characterised by high levels of gloss and have a high build. Occasionally they will be used on wooden promotional pens and metal promotional pens.

In general, all promotional pens must be thoroughly cleaned before they are printed to ensure that adhesion is not compromised. To an ink manufacturer, the surface of a pen is regarded as a hostile environment for a printing ink because of the level of handling and contamination it is subjected to. Therefore, virtually all inks are highly technical in formulation and often only launched after years of development. Because of this, they tend to be very expensive, although the amount required to print each promotional pen is minimal and therefore is a minor cost.