Edgebanding is anything but ordinary

edgebandingAs with most woodshop techniques, edgebanding can be discussed in terms of scale. It runs the gamut from a hands-on, one-cabinet-door-at-a-time benchtop activity to a fully automated industrial process where machines do all the work. The banding itself comes in a variety of formats from wood veneer to acrylics, melamine, metals and plastics such as PVC and ABS.

The nature of PVC

Correctly written as poly(vinyl chloride), this is one of the most widely produced and inexpensive plastics on the planet. It’s technically a synthetic plastic polymer: synthetic because it’s man-made as opposed to existing in nature (at least in large volumes), plastic because it can be shaped and polymer because it’s a big molecule with lots of mass.

PVC’s composition is rendered flexible enough to be rolled onto spools for automatic machine feeding, or handling curved edges, by the addition of plasticizing compounds that increase its viscosity and thus its stretching abilities. The most used additives are phthalate esters. An ester is just a compound with an acid-based source and phthalic acid is an inexpensive solution that has attracted some attention during the last few years from both U.S. and European Union regulatory bodies on environmental and health-related issues. There is a move away from low-carbon to high-carbon phthalates and even toward plasticizers that use no phthalates at all. One reason is that these plasticizers don’t chemically bond with the plastics, so theoretically they can migrate to the surrounding air over time if ambient temperatures change or airborne solvents are present.

We will, no doubt, read a lot more about the effects of PVC use in manufacturing and also in our food chain in the next few years. For example, the National Institute for Occupational Safety and Health published a paper in July 2012 that stated there is increasing concern about human exposure to phthalates and, in fact, most humans who have been tested have had benign but still existent levels of these chemicals in their urine. Bottom line: at this time PVC seems to be a safe, extremely viable option for edgebanding and the way in which it is plasticized will probably change for the better over time.

It’s a white, powdery substance before it’s processed into edgebanding. Once manufactured, it can deliver a massive array of colors and patterns that can perfectly match — or contrast with — plastic laminate sheets and Melamine. Rolls come in a variety of widths, the most common being just under an inch and up to about 0.02” (5mm) thickness. Many manufacturers offer more flexible 1mm to 3mm thicknesses for radius work and tighter spooling. PVC tape is usually applied by a machine that heats an adhesive and also applies it, seats the tape using pressured rollers and then trims the excess. PVC can be harder on trimming blades than most other banding. Some tapes are available pre-glued and most manufacturers will recommend hot air rather than a hot iron as the material is plastic.

Disposing of PVC waste in a responsible way can be challenging. It can be recycled if it’s ground and remanufactured, but it shouldn’t be burned because that releases dangerous gas compounds into the environment. It’s actually pretty resistant to fire, but once the conflagration gains enough heat, the gas released is toxic. Hence, it’s not an option for laser trimming. In a landfill, it takes a long time to decompose and resists naturally occurring solvents in soil or the UV in daylight if it becomes exposed.

The ABS option

Acrylonitrile butadiene styrene (ABS), a thermoplastic polymer, is far more popular than PVC in European shops (North American woodworkers are still using both). Another large molecule, ABS is very reactive to heat (hence the “thermo”). At higher temperatures, it becomes quite pliable and at lower ones it regains rigidity. As such, it’s ideal for injection molding and extrusion processes. It changes from a solid to, well, almost a liquid at about 220 F (105 C). This is known as its “glass transition temperature,” and it’s the point at which it becomes malleable and rubbery in texture. That’s not surprising, as it is made by chemically combining acrylonitrile and styrene, using a man-made rubber called polybutadiene.

Acrylonitrile is an organic compound (vinyl and nitrile) that has been made in labs since the 19th century, so we know a lot about it. Today, scientists are exploring green ways to harvest it as a byproduct from biomass and especially biodiesel manufacturing. ABS is tough, durable and impact-resistant at normal planetary temperatures (about 0 to 150 F). Chemists can change its properties by changing the volume of various components and also by changing the temperatures at which it is manufactured. For example, banding baked at very hot temperatures will end up having a high-gloss surface, but won’t be quite as impact-resistant and will be a bit more brittle.

According to the Swiss edgebanding manufacturer Rehau (rehau.com), ABS “is chlorine-free both during manufacturing and in the final product. Unlike PVC, ABS may be incinerated with general waste, is lighter in weight and highly heat resistant.” However, it is susceptible to strong solvents and/or light sources, and it also costs a bit more on average. Some of that can be recouped when knives last longer and in time when lasers can be used in trimming thicker ABS banding (and also in some design/engraving applications) because of the lack of toxic gases when the tape is burned.

Melamine

Melamine edgebanding can be ordered to match the color or grain of melamine-surfaced panels and it comes in a variety of common widths from 5/8” to 2” in pre-glued versions. Unbacked rolls are generally 7/8” wide and about 500’ long.

When woodworkers talk about melamine edgebanding, they’re actually calling a compound by just one of its ingredients. The basic building block here is melamine-formaldehyde resin, which is a pretty safe product according to the U.S. Food and Drug Administration. In a report (UCM 199525) that was updated in June 2014, the FDA discussed the use of this formula in tableware and concluded that there was virtually no health risk involved. In fact, the results of testing concluded that migration of melamine from the dishes was actually 250 times lower than the level that the agency has concluded is acceptable in most foods.

Natural wood banding

Wood veneer banding can be purchased as either raw wood or prefinished with a sealer and topcoat. Many species are available with a thin fleece or fabric backing that stops them from splitting along the grain. Wood banding is available in both pre-glued (iron-on) and glue-less versions and there are some peel-and-stick options, too.

Wood edgebanding can sometimes be ordered in very wide widths for applications such as mantles or other architectural details where continuous grain patterns are important. The tape is often a bit thicker than plastic banding too and this can be important with raw, unfinished wood when one considers how the completed panels will be sanded. If the banding is too thin, that can be a challenge as it’s easy to sand right through it either on a machine or by hand.

Glue types

In the search for the elusive “zero bond” (where the line between tape and panel is essentially invisible), some thicker edgebanding needs to be applied slightly concave to hide the glue. That’s because most edgebanding tape is applied using a relatively thick layer of hot-melt adhesive that can be difficult to compress and can lose its effectiveness if spread too thin. Hot-melt glues come in a variety of formulations. They can be water- or solvent-based and will have one (or a combination of) these acronyms: EVA, PUR, PA, APOA, and PO.

EVA (ethylene-vinyl acetate) can be melted many times without losing its stickiness, so there isn’t a lot of waste. It also cures quickly and is relatively inexpensive.

PUR (polyurethane reactive glue) sets quickly, but is a bit slower to fully harden as it is more of a chemical reaction than a mechanical one. It uses moisture in the wood and the air to initiate that reaction, so it’s actually a pretty good choice for some veneering jobs. The resulting bond, which can take days to reach full strength, is exceptionally reliable. While PUR glues cost a little more, they have some environmental advantages, plus they can be easier to clean up and can adhere better to oily woods.

PA (polyamide) hot-melt adhesives are designed for high performance in severe environments. They are made with organic bases such as seed oils and they are noted for high heat tolerance. They deliver an exceptional bond, but can be a little more susceptible to moisture (and slight foaming, which can leave some spots without glue) than other options.

APOA (amorphous polyalphaolefin) hot-melt glue is popular in the automotive world: it resists fuel and acid better than most adhesives. It also has a longer open time and slower set time than EVA glue. And PO (polyolefin) has a high melting point and thus higher heat resistance, plus a longer open time than EVA.

The future could lie with adhesives developed for high-tech applications, such as silicone-based versions that retain more flexibility.

Machinery suppliers

A number of manufacturers supply larger edgebanding machinery, including but not limited to Biesse Group NA (biesse.com), CNC Factory (cncfactory.com), Felder Group USA (feldergroupusa.com), Grizzly Industrial (grizzly.com), Holz-Her (holzherusa.com), Laguna Tools (lagunatools.com), Martin Woodworking (martin-usa.com), NexTech Machinery (nextechmachinery.com), Oliver Machinery (olivermachinery.net), Safety Speed (safetyspeed.com), SCM Group NA (scmgroupna.com), SNX Technologies (snxtechnologies.com), Stiles Machinery (stilesmachinery.com) and Virutex (virutex.com).

Many companies also offer portable solutions such as Adamik, Co-Matic, Festool USA, LeMatic, Maksiwa and ShopGear.

For more, visit the Woodshop News online Resource Guide at www.woodshopnews.com.

This article originally appeared in the May 2017 issue.

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