ADHESION- Is the tendency of dissimilar particles and/or surfaces to cling to one another (cohesion refers to the tendency of similar or identical particles/surfaces to cling to one another). The forces that cause adhesion and cohesion can be divided into several types. The intermolecular forces responsible for the function of various kinds of stickers and sticky tape fall into the categories of chemical adhesion, dispersive adhesion, and diffusive adhesion. In addition to the cumulative magnitudes of these intermolecular forces, there are certain emergent mechanical effects that will also be discussed at the end of the article.
ADHESIVE BLEED –Adhesive oozing from the edge of the laminate or label
BIODEGRADABLE- A material or composite such that, when left alone, breaks down and is absorbed into the eco-system without compromising it. As a result, if a biodegradable product ends up in a landfill it will lack the environment required to biodegrade the product in a timely manner.
BIT-MAPPED IMAGE- Type of graphics from paint programmes formed by fixed array of dots that is not conveniently ‘scalable’. Enlargement will typically produce a jagged appearance.
BLEED- Adhesive oozing from the edge of a web, sheet or label, usually under excessive heat or pressure
BUBBLE FREE ADHESIVE- special adhesives with adhesive free channels that allow air to escape from under the film during application. They help to decrease labour time and ensure a bubble free appearance to applied graphics. They are easier for less skilled applicators to apply on flat surfaces but still require skilled application techniques for more complex applications like vehicle wraps.
BUTT CUT- Cutting into the surface of the laminate in the desired configuration for the labels but not allowing for any waste between one label and the next.
CAD CAM- Computer aided design and manufacture (with numerical control)
CALENDERED FILMS-Calendered films are top sheets that are produced by the calendaring method. PVC ingredients are mixed using temperature into a dough like lump and then pass through a series of rollers to achieve the desired thickness. The adhesive and backing paper is then added.
CALIBRATION- Setting equipment to a standard measure in order to produce reliable and repeatable results.
CARBON FOOTPRINT- A measure of the environmental impact of a given process, event, product, or person measured by the amount of greenhouse gases emitted.
CAST FILMS– Cast films are top sheets that are produced by the casting method. PVC ingredients are mixed using solvents into a liquid that is poured onto a casting sheet. The sheet moves through a series of ovens where the solvents are evaporated to produce the final top sheet. The adhesive and backing paper is then added.
CHEMICAL ADHESISION- Two materials may form a compound at the join. The strongest joins are where atoms of the two materials swap or share electrons (known as ionic bonding or covalent bonding, respectively). A weaker bond is formed if a Hydrogen atom in one molecule is attracted to an atom of nitrogen, oxygen, or fluorine in another molecule, a phenomenon called hydrogen bonding.
Chemical adhesion occurs when the surface atoms of two separate surfaces form ionic, covalent or hydrogen bonds. The engineering principle behind chemical adhesion in this sense is fairly straight forward: if surface molecules can bond, then the surfaces will be bonded together by a network of these bonds. It bears mentioning that these attractive ionic and covalent forces are effective over only very small distances – less than a nanometer. This means in general not only that surfaces with the potential for chemical bonding need to be brought very close together, but also that these bonds are fairly brittle, since the surfaces then need to be kept close together
CLIP ART- Stock line art or photographs the use of which is not restricted by copyright.
CMYK- Cyan, magenta yellow, and black (K). The process colours, or subtracting primaries, used when reproducing colour illustrations. The inclusion of black enhances the colours and also ensures the printing of a true black where required. Cf RGB.
COHESION- refers to the internal strength of the adhesive and the ability of the adhesive to stay together. Highly cohesive adhesives are useful in removability ensuring the adhesive stays together on removal. They can also control shrinkage levels of the top sheet by holding the vinyl in place.
SURFACE ENERGY– all substrates have a surface energy value. These are measured in dynes. The lower the dyne value the more difficult it is for an adhesive to stick.
COLOUR PROOF- A reasonable representation of what the final printed image will look like. The resolution and quality of colour proofs produced from different systems can vary considerably.
COLOUR SEPERATION- For process colour work the image is divided into four separate colours. Each colour is represented on a separate piece of film as lines of dots are set at specific angles. When overlaid, the combined layers of dots form tiny rosette patterns that simulate shades of colour when seen at a distance. When required for line printing the separate films still represent each of the colours, (there may be more than four), but no dot formation or rosettes are involved.
COMPOSTABLE- Products that are biodegradable, but also release nutrients into the soil. These products need to be composted in an industrial composting facility and typically take several months to breakdown.
CONVERSION, CONVERTING- Related to self adhesive label laminates, these terms in Europe tend to cover printing as well as die cutting, matrix stripping, punching, overlaminating and so on.
CORE- The tube made of paperboard or plastic, on which laminate is delivered from the supplier and the printed labels are finally supplied to the label user.
DESTRUCTIBLE MATERIALS- Face materials that break into fragments when removal of an applied label is attempted, ensuring tamper evident properties.
DIE CUTTING- The action of cutting or bursting through the required number of layers of material in the profile of the required shape.
DOT GAIN- The increase in dot size, or shape, between the film stage and the final printed image. This gain can be considerable. 15% or more, and can drastically change the perceive appearance of the colour being printed.
FOUR COLOUR PROCESS PRINTING- The process of the reproducing colour graphics using cyan, magenta, yellow and black (CMYK) to replicate the colours produced in a photographic original.
GREENHOUSE GAS- Any gas that absorbs thermal infrared radiation in the atmosphere. This includes gases such as water vapor, carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), chlorofluorocarbons (CFCs), hydro chlorofluorocarbons (HCFCs), ozone (O3), hydro fluorocarbons (HFCs), per fluorocarbons (PFCs), and sulfur hexafluoride (SF6).
GREY SCALE- The perceptible degrees of black below 100% coverage. The 8 bit scale can cover some 256 different shades.
HALFTONE SCREEN- A pattern of dots of different sizes used to simulate a continuous tone photograph in either colour or black and white.
LIFE CYCLE ASSESSMENT- The method of evaluating a product’s total environmental impact from raw materials through materials processing, manufacture, distribution, use, repair and maintenance, and disposal or recycling. Often described as cradle-to-grave.
MECHANICAL ADHESION- Adhesive materials fill the voids or pores of the surfaces and hold surfaces together by interlocking. Sewing forms a large scale mechanical bond, Velcro forms one on a medium scale, and some textile adhesives form one at a small scale.
MICRON- Metric unit, 1 micron = 1 micrometer = 0.001 mm = 1μm (also called mu or mü in Germany and sometimes written um or my). A micron is actually at the limit of visibility since it is near the wavelength of red light. Ink films may be just a few microns but that dimension is normally not relevant in terms of the mechanics of a printing press.
MIGRATION- Movement of adhesive, ink, or colouring, from the side to which it has been applied through to the reverse side of a face material. A phenomenon controlled by application of a protective coating to the reverse side of the face material.
MIL- American term for 0.001 inch = 0.0254mm (by definition). Practical conversion to mm or microns should be approached with caution as the last few digits in the metric equivalent are likely to be irrelevant. For instance, 5 mil usually means something between 0.12 and 0.14 mm rather than 0.127 mm exactly.
MONOMERIC PVC- In order to make PVC soft, additives called plasticizers are added. Monomeric refers to the type of plasticizer. Monomeric (“mono” meaning one) are single molecules. Because of their singular nature they tend to be more unstable and migrate out of the film more readily then polymeric plasticizers causing a faster deterioration of the film. As such monomeric PVCs are usually shorter to intermediate term films.
ORANGE PEEL EFFECT- A result experienced with flexo printing when the ink has been over-thinned making it impossible to achieve good even colour coverage. Colour in what should be solid areas appears blotchy.
PERMANENT ADHESIVE-Permanent adhesives have higher adhesion values. They are designed for more demanding long term applications.
PIXEL (PICTURE ELEMENT)- The smallest element of an image that can be individually processed, smallest distinct unit of a bitmapped image [displayed on a screen]. One halftone, or process colour dot, may spread over two pixels.
POLYMERIC PVC– In order to make PVC soft, additives called plasticizers are added. Polymeric refers to the type of plasticizer. Polymeric (“poly” meaning many) are linked molecular chains. Because they are linked they tend to offer more stable and durable PVC constructions. Polymeric films are more intermediate to high grade films.
POST CONSUMER WASTE- A product that has been used by the consumer and has entered the waste stream.
PRE CONSUMER WASTE- Waste that was generated in the manufacturing process (trim, startup material, etc) and then reintroduced into the manufacturing process.
PVC- Poly Vinyl Chloride.
RECYCLED CONTENT- Post consumer, pre-consumer waste, or both used in a product.
RECYCLING- The treatment or processing of waste materials to make them suitable for reuse in the same or another application, thereby reducing the waste stream.
RELEASE LINER– Paper or film with silicone release coating carrying the adhesive face material; also called backing
REMOVABLE ADHESIVE- The industry definition of removable is an adhesive that when removed will leave less than 30% glue residue however good quality removable adhesives can leave no to minimal glue.
RENEWABLE RESOURCES- Sources of energy or materials that are replaced by natural processes at a rate comparable or faster than their rate of consumption by humans.
SAV- Self Adhesive Vinyl.
SEMI PERMANENT ADHESIVE- offer adhesion values between removable and permanent and are ideal for applications requiring more adhesive strength but also removability characteristics.
SUSTAINABILITY- Meeting the needs of the present without compromising the needs of the future, utilizing principles that balance economic benefits with social and environmental benefits, or balancing economic and social benefits without jeopardizing the environment.
TACK– Refers to the initial bonding of an adhesive to the substrate (High tac, Low tack). Tack is not necessarily an indication of long term adhesion ie an adhesion can be low tack initially to make application easier, then increase in value over time to give strong bonding during the life of the graphic.
TAMPER EVIDENT LABELS- Labels that after application will fragment or split (leaving a VOID message) when removal is attempted.