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A multi-layered paper or film face stock with a layer of adhesive applied to a silicone coated paper or film liner. Once removed from the liner, the face stock/adhesive will adhere to most any surface by use of slight pressure, no other outside influences, water, heat, etc., are needed.

First, the face stock. This part of the construction is the visible part of the label that is usually printed on by means of a flexographic press or some type of a printer. This face stock can either be paper, film or synthetic paper. Different types of face stocks are used for different applications. The most common is of course paper. Paper labels are found on everything from food to auto parts to medicine to just about anything that requires some sort of identification. Price is generally the main factor in choosing paper. Durability is usually not an issue with this material although overlaminates and varnishes are used occasionally to protect the label’s overall appearance and prolong its livelihood.

The other option for a label face stock is film or synthetic paper materials. These are made from poly materials such as polyester, polyolefin, polystyrene, polyethylene, and polypropylene. Incidentally, all of these products are petroleum based therefore are subject to the price fluctuations in the oil and gas markets. If gas and oil go up eventually so will the raw materials for these labels and somewhere down-stream, it ends up costing you and I, the consumer. Poly labels are mostly used in extreme environments. Excessive moisture, heavy oil exposure, high abrasive situations, and certain food products require these labels.

Another application requiring a poly label is for high heat tolerance such as printed circuit boards and certain types of electronics. For this particular need, a material called polyimide (pronounced “poly-m-id”) or trade name KAPTON is used. This product will survive temps approaching 500 degrees Fahrenheit whereas paper burns at 400 degrees Fahrenheit. Due to its durability, is also more costly.

The next layer of the pressure sensitive construction is the adhesive layer. This is probably the most technically important part of the construction. Adhesives are for-mulated for specific applications and all have performance characteristics unique to themselves. Basically adhesives fall into two groups, permanent and removable. Permanent adhesives, while diverse in nature, all aim at one goal, to permanently attach a paper or film label to a specific surface. A permanent label, correctly applied and allowed to cure, will require a diligent amount of effort to remove. In most cases solvents and scrapers will be involved in this process and unless extreme care is taken, what ever the label is applied to will be marred or damaged in the removal.

Removable adhesives are a horse of a different color. In all cases when dealing with removable adhesives, it is necessary to test for compatibility. Some removable adhesives, when applied to certain surfaces, will exhibit permanent characteristics after being exposed to heat or passage of time. Then, in other instances removable labels will not adhere to hard to label surfaces very well or at all. After the point where the end user has labeled 50000 pieces of their product, boxed and shipped them, is not the time to discover any of these issues.

A simple test for both the permanent and removable adhesives is to apply a sample label to the product and place it in an oven at 120 degrees Fahrenheit. The heat will age the adhesive at a rate of 24 hours for every 2 hours that the object remains in the oven.

After 12 to 24 hours of oven testing, it is possible to get a reasonable idea of how the label will perform long term. Of course for definitive testing, we are able to send a sample of the product to our raw material suppliers and have them do the testing in their labs.

Finally, in the pressure sensitive construction, there is the liner. This part is one of two types, either paper or film. Which one to use is dependent on what the application demands are. Paper is once more the most cost effective and will satisfy most needs.

Film is primarily used in situations requiring additional liner strength, such as a high-speed automatic application on an assembly line where the need to prevent liner breakage offsets the additional cost. Both of these liner types are silicone coated and are available with all types of face stocks and adhesives.

Concluding that in labels there is no “one size fits all”. It is critical that as a converter, we know exactly, specifically, and in minute detail what your labels needs are, because it is always that little detail by which we are all hoisted.



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