Specifications on self adhesive labels

It is important, when anticipating the use of any form of self adhesive label, to be aware of the variety of details affecting your choice, and the reasons why these decisions must be made.
The initial selection must be of:   Label Size,  Face Material and Adhesive, however, the choice of any of these factors could, and probably will, depend on at least two of the following;
a) The method of 'printing' information onto the label.
b) The environment in which the finished label will be used.
c) The surface on which the label will be attached.
d) The expected 'life' of the label.
e) The type of information to be added.
If we consider these points it will soon become evident how and when decisions must be made.

Face Material
This is literally the material the label is made of and for the majority of retail labelling needs it will be paper, although there are many synthetic products, such as Polyethylene, Polypropylene, Nylon, Vinyl and Metallic Foil, which are all in common use.
Most face materials are described by their weight in 'Grams Per Square Meter' (gsm), for example 90gsm, and in addition the surface might be 'coated' or 'uncoated'. The terms 'Matt', Semi Gloss' and 'High Gloss' typically describe these finishes.
Some face materials, particularly metallic foils, will be described by their thickness, either in thousandths of an inch (mil) or thousandths of a millimetre (micron). There are no exact standards as to which is used but in the UK it is more common to see the metric version (mil).

Backing Paper
Usually a 'Glassine' material that has the twofold purpose of supporting the labels in a roll or fanfold stack and having the properties to allow any label to be removed with ease, regardless of the adhesive type.
The backing paper can be in a selection of colours ranging from white to blue but in most circumstances this will not be a decision you will need to make. If, however, you are intending to overprint the labels using a 'Thermal Transfer' printer a 'craft' or 'honey' colour backing paper will be required so that the machine can differentiate between label and backing.

Adhesive
In general terms there are two descriptions for adhesives; 'Permanent' and 'Removable'.
Both types are intended to adhere securely to a surface, permanently in one case and in the other to be peeled off when desired.
There are many variations of specifically designed adhesives; Opaque, Freezer, High Temperature, Food Grade, Clothing etc. all with their own properties and method of use.   Each case will have to be considered separately and advice sought if doubts arrive.
Opaque (or 'blockout') adhesive is particularly useful, and indeed sometimes necessary, when using a label to cover existing barcodes or text. The 'blue' or 'black' tinted adhesive does not permit information to be seen through the label which, in the case of barcodes, could have caused incorrect scanning

Print Method
Multi-colour and long 'print runs' of self adhesive labels can be produced by a variety of conventional printing processes; Letterpress, Flexography and Offset Litho, or a combination of these and others.
Methods of production may dictate the types of inks used i.e. Water based, Analine, U.V. Drying etc.,   but so may the intended use when, for instance, certain chemicals within the adhesive may not be compatible to food products, or other inks may fade very quickly in direct sunlight.

To be able to produce labels 'in house'( either on plain or pre-printed label stock) Direct Thermal and Thermal Transfer methods of printing can be employed.    In both instances information such as barcodes, logos, text and sell-by dates can be added 'on demand', providing a highly flexible and cost effective labelling solution.

Direct Thermal
The 'Direct Thermal' method of printing requires the label stock (face material) to made from specially treated paper which is activated by the direct application of heat (a fax machine operates in this manner). This type of label tends to be used for internal and short-lived requirements, as it not only fades with time but reaction to heat and moisture limits the scope of use.

Thermal Transfer
Thermal Transfer printers work by passing conventional label stock and ink impregnated ribbon (historically called a 'foil') under a heat activated print head. In this manner it is possible to produce a more resilient printed surface than can be achieved with the 'Direct Thermal' method. Also by using selected ribbons different colours of print may be achieved.
Great care should be taken to ensure that the correct type of ribbon, of which there are many versions, is used, especially when barcodes are to be printed.
Axicon Labels have conducted extensive trials on the interaction between Ribbon and Material types and consequently will be able to advise you on all aspects of demand label production.