Printing Symbols

There are several ways to approach the application of bar codes to your products. You can decide to incorporate the bar code into the products printed packaging design or apply it to the product on an adhesive label either prepared in your office or by a print company. Alternatively depending upon you manufacturing process you can also consider online printing, where labels are applied to products during the manufacturing process.

Whatever method you chose to apply a number of things must be considered. These are size, bar height, quiet zones, colour, quality and placement.

Symbol Size

Bar codes can be printed in various sizes. The size to be selected, besides the scanning environment, depends also on the printing conditions. A small bar code can be used if good quality printing is coupled with a good quality substrate. It is not possible to select an arbitrary symbol size to fit a predetermined space on the package.

For each type of bar code, the size may vary between a minimum size and a maximum size. For direct printing, it is determined by the printer after tests. Equipment that constructs bar codes from pixels or dots will not be able to produce bar codes in the full range of sizes.

Another factor that should always be taken into account when deciding about the bar code symbol size, should be the environment in which it is to be scanned. Symbols intended for retail applications may be as small as the print quality permits, whereas the bar codes for warehouse environment should be as large as is necessary to allow scanning from a considerable distance, i.e. by an operator of a truck.

Symbol Quality

The printing conditions must be checked regularly throughout the print run to ensure they have not deteriorated since the initial assessment was made. There are various means to assess the quality of a bar code. Simple visual ways can be used. An example is the printing of an H of given dimensions inside the bearer bar of an ITF14.
Truncation

Truncation, (reducing the height of the symbol) removes the omnidirectional capability. Truncation should be a last resort and is not recommended.
Quiet Zones

All types of bar codes must have Quiet Zones (i.e. an empty space), before the first bar and after the last bar.

This Quiet Zone is extremely important and must be respected. The size of the Quiet Zone area varies depending on the symbol size and type of the bar code. Any print within Quiet Zones can prevent the bar code symbol from being read.

Symbol Contrast

Scanners work by measuring reflectance. There must be sufficient contrast between dark bars and light spaces and sufficient density of ink in the bars so as not to create voids.

Scanners use a beam of red light. A contrast that seems to be satisfactory for human eyes may be insufficient for scanners.

Symbol Colour

Bar codes can be printed in various colours. A general indication is that light colours including red and orange are suitable for the spaces and quiet zones. Dark colours including black, blue, and green are suitable for the bars. Composite colours are not adequate to print bar codes. It is best to use solid colours. Please refer to the following colour chart for reference.

Highgloss substrates may change the reflectance and checks must be made before printing. Transparent overwraps may also reduce contrast and checks on the completed package should be made if overwrapping is used.