Basics of a Bar Code Label
What is a Bar Code?
Think of a bar code as Morse Code in light. They are really just dots (narrow bars) and dashes (wide bars)
and that's how the scanner sees them, not as bars. A laser scanner has one beam of light reflected off
of a vibrating mirror. It "rasters" so fast that it looks like a solid bar. The light reflected back to the
scanner enters in the form of a dot or dash, just like the old ship-to-ship messages in old war movies.
Compared to Morse Code, however, there are numerous ways to arrange the dots and dashes. The different
arrangements are called SYMBOLOGIES. Each has a different strong point and weak point. The name may tell
you something about the key feature of the particular code.
What is CPI?
Characters Per Inch represents how much information
you need to fit onto the label. By varying the width of the narrow element in any symbology you can make the
code bigger (easier to decode) or smaller (more of a challenge). You probably will not need to get too technical
about this, just find out the number of characters to be encoded and measure the space available for the code.
Two things to remember about CPI: First there is always a start and stop character so add two characters to
your calculation. Start and stop characters are unique to each symbology and tell the scanner's software
which symbology (code) is about to come up and that the data has ended (like a period to end the sentence).
Second, Quiet Zone! There must be approximately a 3/16" on either side of the code. Do not add this 6/16" (front and back 3/16") to the CPI calculation; rather, subtract it from the space available.
What Environment Will Your Label Be Exposed To?
WLP produces labels on four different materials; paper, polypropylene, polyester (with numerous subgroups)
and polyimide. In addition, WLP's process protects the bar code with various clear films or a clear
UV coat. It helps to know what you will be labeling so WLP can recommend the right construction.
- How long does this label have to survive and where?
- Will it get wet?
- Will it be outdoors?
- Will chemicals be present?
- Which ones?
- Will it be hot?
- How hot?
- How long?
- Will things be scraping against it?
- Will it be cleaned?
- With what?
These are all important to the ultimate success of the system. Tell us as much about the environment as you can.
What is a Substrate?
What will the label be sticking to? Give WLP a sample of the substrate if it is an "exotic"
material. WLP recommends different adhesives for different surfaces (for example, plastic vs. metal). Our
process lets us put the adhesive on after the facestock is imaged, so we can supply an adhesive that will
best adhere to the substrate. More bar code labels fail due to poor choice of adhesive than due to bad bar
codes. The adhesive is the easiest place to fail and the easiest place to succeed.
What Will My Label Cost Me?
Watson Label Products produces the finest bar codes and the best labels in the business. WLP's prices are comparable to the
competition, but the product and the service are not comparable. They are better!!!