Lamination is the process by which two or more layers of material are glued together and placed within a plastic covering as to protect them from damage and normal wear and tear or deliberate damage. This type of lamination, which is the one that people most commonly refer to, should not be confused with the type associated with electrical engineering, which is a technique used to reduce undesired heating effects. The plastic covering sheath used to cover the materials is known as a laminate. Credit cards, photo ID cards and formal documents are some of the most commonly laminated items, but the process is used for protecting virtually any paper document that might need protection, such as school reports and diplomas.
An 19th century dentist named Dr. Morris M. Blum invented lamination, by accident, in 1938 when he used dental laminate (also known as a dental veneer) to laminate a picture of his wife.
Pouch lamination is a method by which the material being laminated is placed in a plastic pouch and passed through a laminator. As the material is passed through the pressurized lamination roller the inside of the pouch is coated with a heat-activated veneer that sticks to it and forms a seal on one side of the material. The number of rollers a laminator has is correlated with the quality of the lamination since the rollers are designed to distribute the heat evenly while keeping the lamination film pressed shut. Moderately-sized pouch laminators, such as desktop laminators, are ideal for use in the home or the office and for relatively small projects while larger industry grade laminators with larger rollers are recommended for voluminous jobs.
Laminating pouches are rated by thickness and laminators are compatible only with pouches that are smaller or equal to the laminator’s maximum thickness capacity. The standard unit used for pouch thickness is a “mil,” (not to be confused with “millimeter”) which is one thousandth of an inch, and the common pouch thickness measurements are 3, 5, 7 and 10 mil. 3 mil pouches can protect against light spills and stains while 5 mil offers longer term protection and is resistant to bending. 7 and 10 mil pouches are the most durable and offer the best protection for items such as ID cards, luggage tags and pipe markers.
Roll lamination is different from pouch lamination in several regards. For one, roll lamination is more commonly used for industrial-grade and high volume jobs, largely because the adhesion process is much faster. For example, roll laminators melt the glue before it is applied to the substrate (or underlying layer of material) which makes for a more expedient lamination process. The glue used in this process is also non-adhesive until heated, which makes it easier to handle unlike with pouch lamination which uses an already-adhesive layer. Since the glue is only pliable in heated form, once it cools and dries it is less likely to warp, which means solid and high quality laminations.Cold roll lamination uses a “stick-on” method where the user peels off a glossy back cover to expose the adhesive and then sticks the lamination cover onto the desired item. Cold laminators are highly compatible with wide format inkjet printers, which often use inks not suitable for hot laminators. Cold lamination is not limited to the printing industry and is also commonly used for coating stainless steel, such as metal signs, or sheet glass.