Tech Specs: Barcode Labels

Dimensions: ALWAYS Width by Length!

The commonly agreed upon standard for describing labels is always width by length, with the width stated first. The width of the label is determined by how it feeds into a barcode printer.

For example, a "4 x 6" label would be 4 inches wide, and 6 inches long. The label would feed into the printer on the 4-inch side.

Keep in mind that some labels may be printed "2up," "3up," or more. This means that two - or three, or more - labels fit side by side. The dimensions of the label are the same, but the label description often includes "2up" (or the appropriate number). So, in our example above, if we had a roll of 4 x 6 labels (2up), the actual label width would be a little over 8 inches, or two times four. (There may be some spacing between the labels on the "liner," which is the non-sticky paper the labels are on before they are peeled off and stuck to the package or product. This spacing between labels adds to the overall width of the label.)

Thermal Transfer vs. Direct Thermal, and What's the Difference?

Thermal Transfer - A heated printhead melts the wax, resin or wax/resin material in a barcode ribbon, and transfers the melted material to the label. Thermal Transfer printing always involves a ribbon!
Direct Thermal - Specially treated paper passes under a heated printhead, and the paper reacts to the heat to generate the image. Direct Thermal labels are more susceptible to temperatures (direct sunlight or exposure to heat sources will darken the label), and they are not as durable as Thermal Transfer labels for many applications.

Label Materials: Paper, Kimdura, Polyester, Kapton, and More!

Paper - Standard for most labels because of cost factors and general usability. Paper labels are adequate for shipping labels, shelf marking, and other general duty applications.
Polypropylene - Similar to polyethylene but stronger and having a higher temperature resistance. Excellent clarity. Also used in various thickness in the printing of labels as well as backing or liner materials.
Polyolefin - A generic term for cross-linkable thermoset polymers. Polyolefin heat shrink tubing is usually made from polyethylene and its copolymers.
Polyester - A strong film having good resistance to moisture, solvents, oils, etc. Usually transparent, although available with opaque ester formed by polymerization or condensation. Excellent strength, clarity and dimensional stability.
Kimdura - High-quality, durable polyolefin label resistant to tearing and moisture, plus moderate resistance to temperatures and chemicals. Can be used outdoors for product or shelf marking, tool tracking, building materials, etc.
Polyethylene - A tough, stretch plastic film having very good low temperature characteristics, also used a great deal for producing semi-rigid recyclable bottles.
Kapton (a.k.a. Polymide Kapton) - Made from a polyimide material for high-heat applications (up to 480 degrees Fahrenheit. High temperature, chemical, and smear-resistance. Available in matte or gloss topcoat.
Vinyl - A tough durable plastic film having excellent resistance to oils, chemicals and many solvents. It has excellent abrasion-resistance, and can also be colored. Its high stretch is due to the addition of plasticizer.

How Do You Want Labels to Load: Rolls, Fanfold, or Sheets?

There are three basic ways labels can feed into a printer: By unspooling from rolls, by unfolding from stacks, or by single sheets feeding into a laser or inkjet printer.

Rolls - Rolls come in a variety of sizes to match the type of printer they will fit into. Desktop printers will need smaller rolls generally than midrange or industrial printers. Rolls are dispensed from a hanger that sits externally near the printer or inside the printer. Each roll will have an inner "core" (see below) that fits on the hanger. Some printers may have an internal mechanism to rewind the labels, or a rewinder can be purchased for this purpose.
Fanfold Stacks - Fanfold labels are sometimes more cost effective than rolls, and fanfold labels are sometimes overlooked when considering labels for a specified application. Fanfold labels are usually sold in cases only. Loading fanfold labels is no problem, and may present a better alternative for loading than odd-shaped rolls, which may require special hangers or takeup reels to use.
Sheets - Labels for inkjet or laser printers can be purchased in a variety of dimensions and colors, but labels printed on these types of printers are not always readable by machine scanners, because the print resolution may not be adequate to ensure a crisp printout. In addition, laser or inkjet labels may have more waste than other types, because if only one or two labels are needed at a time, the rest of the sheet may be unused.

A Note About Core Size and Outer Diameter

Core Size - The core size is the diameter - usually expressed in inches - that the roll of labels is wound around. The most common sizes of cores are 1-inch and 3-inch, but 4-inch cores are also available. Be sure to choose the correct core size to fit your printer! Some adapters or special roll dispensers may be available to allow you to use larger core sizes on your printer.
Outer Diameter - The outer diameter is the size - usually expressed in inches - of a new roll of labels. The most common outer diameters are 3-inch and 8-inch, but other sizes may be available for specialized printers, such as portables or high-capacity print-and-apply systems. Some adapters or special roll dispensers may be available to allow you to use larger outer diameters on your printer.

Getting Stuck on Your Labels: All About Adhesives

Some important considerations when choosing an adhesive - even bfore you get to the adhesive! - are:

What type of surface will the label stick to? (i.e. Glass, cardboard, metal, paper, cellophane, etc.)
What type of label material will be used? (i.e. Polyester will "behave" differently with different adhesives than paper with comparable adhesives)
How will the label be applied? (i.e. By hand, by machine, wet process, etc.)
What kind of conditions will the label be in once it's applied (i.e. Cold temperatures, or temperature extremes, chemicals, heavy handling, etc.)

Consider these three properties of adhesives as well:

Shear - The measurement of the internal strength of the adhesive to the surface (the "bond" with the surface). Low-shear adhesives may slide or fall off easily, while high-shear adhesives may be more difficult to move. Shear is especially important on curved surfaces, where "flapping" may occure more easily than on a flat surface.
Tack - The measurement of an adhesive's ability to form an instantaneous bond with the surface to which it's being applied. High-tack may form an almost instant bond, where low-tack may allow some time for moving a label around a bit.
Peel - The force required to remove a label.

Here are the different types of adhesives that are generally available:

General Purpose
Acrylic - Pressure-sensitive adhesive based on high-strength, acrylic polymers.
Cold-Temperature - An adhesive that will enable a label to adhere when applied to refrigerated or frozen surfaces, generally 35 degrees Fahrenheit or colder.
High-Temperature - An adhesive that will enable a label to withstand sustained elevated temperature of +200 Fahrenheit or higher.
Permanent - An adhesive characterized by relatively high ultimate adhesion. Sometimes it can be removed when the degree of force used overcomes its bonding ability but generally it is not removable.
Pressure Sensitive - A type of adhesive which in a dry form is aggressively tacky at room temperature. It has the capability of promoting a bond to dissimilar surfaces on contact, with pressure.
Emulsion - A dispersion of fine particles or globules in another liquid. Many adhesives are emulsion systems.
Food Contact - Adhesives meeting U.S Food & Drug Administration codes for direct food labeling as well as incidental contact. Special product recommendations are necessary for specific applications.
Freezer - Adhesives that can be applied and will function at temperatures below the freezing point. They are usually removable at room temperature.
Hot Melt - Thermoplastic materials that liquefy when heated and resolidify on cooling to form a bond with the face sheet the adhesive was applied to and a pressure sensitive lamination which includes a release coated backing sheet.
Silicone - Used for pressure-sensitive adhesives capable of withstanding extreme temperatures.
Solvent - Adhesives' components are dissolved in a variety of organic solvents for coating. Rubber or acrylic-based systems can be coated this way.
Rubber - Pressure-sensitive adhesive based on natural or synthetic rubber. Can be coated as a solvent, hot melt or emulsion system.
Glove Friendly - glove-friendly adhesives work well in cool laboratory temperatures, but allow enough time to apply the label to test tubes, slides or other laboratory surfaces without sticking to gloves.
All Temperature
Removable - An adhesive characterized by relatively high cohesive strength and low ultimate adhesion. It can be removed easily from most surfaces.

White, and All the Colors of the Rainbow

Labels can be manufactured in a wide variety of colors for specific applications or specifications. Pantone colors can be specified for general colors. Pastel colors generally are "softer" and not as vibrant, while fluorescent colors are very bright and vibrant. In addition to label colors, a variety if ribbon colors can be used to enhance the color effect of your labels.

Special Labels for Special Applications

Slits - Slits are cuts in labels that allow companies to take advantage of "multi-part" label applications. For example, an electrical company may choose to print serial numbers on a 4x6 label with slits that allow field workers to detach smaller portions of the label for use in cable marking, and the main label used on a large spool of wire. Slitted labels sometimes require special dies so the labels can be cut to customer specifications. Be sure to factor die setup costs into your planning.
Perforations - Perforations allow for easy tearing of labels or liners, or separation of a label from a larger printed document. Design experts can help you design specialized perforated labels or products to meet your business needs. Factor special printing costs into your barcode planning.
Special Shapes - Special shapes can be manufactured, using dies to cut the exact shape desired. Typically, there is a charge for creating the die to be used, so you will need to factor that into your planning.