Printed Pens & Promotional Pens – Limitations of Metallic Colours

Inks are made up of three primary constituents as follows for Printed Pens and Promotional Pens

• Resin – This can be organic or synthetic depending upon the type of ink. In any case it is usually very hard in its raw state and before processing is supplied to ink manufacturers as chips or in large chunks and occasionally powder. When dissolved in solvent it is called ‘varnish’ or ‘extender base’.
• Solvent – This dissolves the resin and its formulation is very varied depending on the resin it has to dissolve and the printing characteristics desired.
• Pigment – This is the colouring agent. Pigment is supplied in its raw form, usually as powder. However, the particle size is too large for printing purposes so consequently it is not just a matter of stirring it in with the varnish  (Resin + Solvent) – it has to be milled in. This is a complex process and will form the basis of a separate article.

There are countless considerations when considering printing ink properties for pens but we will focus on the limitations of metallised colours in a printing ink that is commonly used on promotional pens.

Inks derive their colours from the pigment component of the mix and the following is a list of the three most common metallic-pigments

• White – This is always  Titanium Dioxide. Not exactly a metal particle in itself but is a derivative of titanium. When mixed it is held in suspension in the varnish.
• Gold – This is invariavbly brass powder and is mixed with the varnish and is held in suspension. It never becomes atomically bonded with the resin.
• Silver – This is virtually always aluminium powder. This is held in suspension in the varnish and no atomic bonding occurs between them.

Clearly, with all of the above, metal pigments just sit in suspension in a matrix of extender base. These elements are protected by the varnish from tarnishing in use except on the surface where they are in constant hand-contact during use on personalised pens or promotional pens. However, over time the constant wear and tear of useage allows hand-borne contaminants, not least of which is perspiration (An agrssive saline solution) to attack the surface particles and in time this will penetrate to the base of the ink. This, unfortunatley, not only breaks the ink down chemically but it also affects the bonding process at the interface of the ink and material of the Printed Pens.

A third destructive action unique to these inks is the fact that the particles comes away from the resin by constant hand friction and this has a scouring pad effect as the particles abrade the ink itself during use. So, in short with the chemical action caused by contaminants on these particles in printing inks and their abrasive nature the poor old ink cannot expect a longevity normally associated with non-metallic pigments.

What is the answer? Well on printed pens there are two

1. Don’t use the pens – put them in a cabinet and just admire them from time to time
2. I expect most people will want to use them so we would advise having an overvarnish to seal the ink under a blanket of non-metallic varnish. This is not a perfect solution for the following reasons

• It is additional cost.
• the varnish will appear as a block and this is more obvious on satin or matt finished pens.

There we have it, no perfect solution but knowledge is empowering and remember you cannot change physics so buyers of promotional pens have to understand the limitations of these types of printing inks.