Edge Banding’s Edge
How many times have you finished a task and realized too late that you made a mistake?
It doesn’t matter if that mistake was something you forgot to do or if you honestly didn’t know that issue existed? Something wrong occurred that ruined your work.
Once, a long time ago before the interwebs, I had been living alone for quite some time, and I was hungry for chocolate chip cookies. I mean, who wouldn’t be, right?
At that time, making cookie dough wasn’t something I wanted to do, so I cheated and bought a tube of dough and sliced it like a loaf of bread.
So, I made the cookies, and after they cooled, I stared at a mound of cookie. What I didn’t realize is that the cookies needed to cool down before stacking.
As I ate my chocolate chip cookie pie, I made a point to remember not to make that same mistake again.
Sometimes the best lesson in life is to burn a finger on a hot light bulb. Or in my case, baking a cookie mound.
Chocolate chip cookies and work surfaces have nothing in common with each other, but somewhere along the way, like me, somebody learned a lesson the hard way.
For me, it was cookies. For that unknown person, it was the need for edge banding.
Edge banding plays a vital role in the useful life of a work surface. However, until the advent of engineered wood in the last century, edge banding didn’t exist.
It Needs to Start Somewhere
Quoting the Jimmy Castor Bunch in their song, Troglodyte:
What we’re gonna do right here is go back, way back, back into time.
Before there were standing tables, desks, workbenches, and counters were the table. Several millennia ago, the Egyptians and Chinese each used a version of the table. Those early tables weren’t used for eating.
Etymology
As tables evolved into the versions seen today, the etymology of the word evolved with it. The word itself comes from the combination of three languages: Latin, Old English, and Old French.
It’s interesting because of the meaning of each version. The word describes “a piece of furniture with the flat top and legs.”
The Table Through Time
The Egyptians started using stone tables to keep things off the floor. Eventually, they started elevating playing boards while finding a use for various smaller tables.
The Chinese, on the other hand, created early versions of the table for writing and the arts.
As time passed, the Romans and Greeks used tables in more ways, including eating. In the Middle Ages, not much was known about table usage; the only kinds described were ones used by the nobles.
Table Evolution
As the world became industrialized, tables transformed into critical accessories for nearly all industries. As manufacturing became standardized, wooden tables turned into metal.
When more people moved to office work, tables turned into desks. Those early versions were made from solid wood.
It became apparent that as the need for tables grew, it wasn’t economical to keep using solid wood. Those desks were spartan in appearance but served its function. However, they weighed a ton!
Eventually, as technologies grew, manufactured wood became the material of choice.
A New Way of Seeing Things
On more than one occasion, I’ve been described as having an unusual mind. From seemingly nowhere, I’m able to pluck obscure facts about random things.
Know how I know when I’ve struck gold with insane trivia? When my wife responds with a sound, I’ve come to know like the back of my hand.
Pfft!
With great power comes great responsibility, so I try to use my brain for good. One day I took a peek at the edge banding along the side of my desk. As the gears wound in my head, I wondered about the evolution of banding.
Specifically, what path did edge banding follow to reach this point?
Well, I found out.
Necessity, the Mother of Invention
As mentioned earlier, edge banding wasn’t necessary for a long time. Tables, then desks, were made from solid materials such as rock, wood, and metal.
The idea of plywood reaches back to our friends the Egyptians and Chinese. The French and English worked with wood on a general principle of plywood, reportedly in the 17th and 18th centuries.
John K. Mayo developed the first patent for plywood in December 1865, but he never capitalized on his invention.
It wasn’t until the 1905 World’s Fair in Portland when a man named Gustav Carlson laminated wood panels from different types of softwoods and called it 3-ply veneer work.
Interest grew in the veneer work from the door, trunk, and cabinet manufacturers and the plywood industry took off.
The need for waterproof plywood resulted in Dr. James Nevin developing a fully waterproof adhesive.
For the engineered wood industry, the rest is history.
Well, except for edge banding. No, I didn’t forget about it.
Edge Banding: Hiding in Plain Sight
In our article about work surfaces, we explain how engineered wood is made. I’m not going to repeat the whole section, but share a portion that’s relevant to this topic.
Modern Edge Banding
Until current applications, edge banding was manually applied using ordinary carpentry materials and tools.
As society progressed, the demand for furniture grew exponentially. Using solid pieces of wood was cost prohibited, so Carlson and Nevin’s work came into its own in the high-volume, repetitive manufacturing industry.
Many different materials went into the creation of plywood, particle board, and MDF. Because of that variety, creativity in edge banding became necessary.
Edge Banding Materials
As a review, the edges of engineered wood are ugly and rough. The jobs of edge banding are to give the appearance of a solid piece of wood and protecting the substrate from possible warping.
There are many types of edge banding used for engineered wood, including the following materials.
PVC
Poly(vinyl chloride), or PVC, is the most commonly produced and least expensive plastics on earth. Technically a synthetic plastic polymer, its composition is flexible enough to be rolled into spools.
Before processing it into edge banding material, PVC is a white, powdery substance. Applied by machinery, PVC tape the adhesive is heated, applied and trimmed.
ABS
Acrylonitrile butadiene styrene (ABS) is a thermoplastic polymer that’s very popular in Europe. ABS reacts well to heat, and at higher temperatures, it’s malleable and when cooled, becomes rigid.
When heated to 220 ºF, ABS nearly becomes liquefied, a stage known as glass transition temperature. At this state, ABS becomes pliable and rubbery.
Melamine
When referring to melamine edge banding, it turns out that’s only one ingredient. Its full name is melamine-formaldehyde resin.
Although considered a low-end paper-based product, melamine has limited color availability and isn’t comparably durable.
Polypropylene
Polypropylene is semi-crystalline plastic regularly used in the plastic industry. It’s popular as an alternative to PVC and ABS materials.
Wood Veneer
Wood veneer edge banding is made from thinly slices of wood, pre-sanded and layered. It can be both finished and unfinished depending on its application.
Wood veneer is available in oak, maple, mahogany, ash, and walnut, plus it’s available in both pre-glued and glue-less versions.
The Glue That Binds
In its strictest definition, adhesives are defined as
…any substance cable of attaching materials employing a surface attachment.
The concept of adhesives goes back to, yup you guessed it, the Egyptians. For centuries, mud, dung, clay, and a mix of these three materials were used to build huts in many parts of the world.
Synthetic polymers that were the basis of adhesives were introduced just before World War II. Until then, all the glues were natural in origin.
Bonding wood together used two distinct groups of adhesive: natural and synthetic.
Natural Glues
Natural glues were usually made from several sources, including:
Animal: Animal glues were traditionally made from the hides and bones of cattle, horses, and sheep. Typically, animal glues didn’t have much resistance to moisture and were tricky to apply because of the necessity to apply at the proper temperature.
Starch-Based Vegetable: The main ingredient of vegetable glues is a variety of plants such as corn, potatoes, rice, and cassava. Before World War II, there were extensive cassava plantations in Indonesia. Because most plantations were destroyed, substitutes appeared reducing the reliance on cassava.
Veggie glues arrive in powdered form and need mixing with water. The resulting paste is heated and applied to wood. These type of adhesives are cheap and have a relatively long pot life, but had no water resistance.
Soybean: Soybean glue is the first protein-based veggie glue. Its characteristics are similar to starch-based veggies but have better water resistance. Soybean glue is moderately strong, and better resistant to damp atmospheres.
Casein: Chunky milk is the basis for casein glue. Casein is derived from the casein curd from sour milk. The curds are dissolved in an aqueous alkaline solvent then dried.
Characteristics of casein glue limit their usefulness. They stain wood rich in tannic acid, dull woodworking tools, and are attacked by molds and fungi.
Blood: Blood-albumin glue comes from whole blood provided by slaughterhouses. Evaporating the serum from fresh whole blood converts the blood into powder. The dried blood powder is mixed with water and other chemicals.
Until synthetic resins, blood glue was the most essential adhesives for plywood manufacturers. The main reason? Its resistance to moisture.
Synthetic Resin Adhesives
Synthetic resins are man-made and resemble natural resins in looks, but are tailored to meet specific woodworking requirements.
These synthetic resins resulted in the highest water resistance of any adhesive.
There are two categories of synthetic resin adhesives: thermosetting and thermoplastic.
Thermosetting Resins
Thermosets literal meaning is setting under heat. Thermosets undergo an irreversible process, and that can’t be melted or fused.
This means thermosets provide excellent stability at high temperatures, retains hardness and rigidity, and resists creep.
There are five common thermosetting resins: urea-formaldehyde, melamine-formaldehyde, phenol-formaldehyde, resorcinol, and phenol-resorcinol formaldehyde, and isocyanates.
Urea-Formaldehyde: These resins are probably the most commonly used thermosetting resins for wood. Urea-resins are widely used in manufacturing particle board and plywood.
If the urea-resins aren’t changed, the resins are light-colored and high moisture resistance.
Melamine-Formaldehyde: When paired with urea-resins, melamine improves moisture resistance.
However, the combination of high curing temperature and their expense, using melamine resins is limited to a few applications such as marine plywood.
Phenol-formaldehyde: Phenol-resins have a wide usage with softwood plywood used in severe conditions. The advantages of phenol-resins over other resins are plentiful, including greater strength, very moisture resistant, better resistance than wood to high temperatures to artificial aging.
Resorcinol and Phenol-Resorcinol Formaldehyde: These resins have a higher price tag than phenol-resins, so they’re used primarily for special purposes. For example, they would be used in solid wood products requiring exposure to weather such as wood aircraft.
Isocyanates: First used in the 1940s, isocyanate-based adhesives could be referred to as the diva in thermosetting resins. Their high costs, technical difficulties, and health hazards prevented commercial applications.
Thermoplastic Resin Adhesives
Thermoplastic resins melt or soften when heated, then hardens when cooled without undergoing a chemical change.
There are only two kinds of thermoplastic resin adhesives, polyvinyl acetate, and hot melt.
Polyvinyl Acetates: Two words describe polyvinyl acetate adhesives: Elmer’s Glue. The eponymous white glue that we grew up with. Another example is wood glue.
This resin quickly sets at room temperature with high dry strength. Resistance to moisture, though, is futile.
Hot Melt: Hot melt adhesives usually are solid, heated to a liquid, then applied as a bead. Once they cool, they regain their adhesiveness.
Jewelry glue guns are the best example of hot melt adhesives.
Sticking It
So far, I’ve explained what edge banding is and its various forms. In great detail, we took a peek at the types of resins used as adhesive.
So now, let’s get these kids together!
Edge Banding Machinery
Companies with a high-volume need for edge banding use an edgebander for applying adhesive to edge banding material to the substrate of work surfaces.
There are two methods of applying edge banding: hot-melt glue edge and hot air.
Hot-Melt Glue Edge Banding
Hot-melt glue edge banding is the most common way manufacturers attach edge banding. Applying hot-melt glue requires cartridges or a glue pot.
The meaning of hot-melt glue edge banding is self-explanatory.
The adhesive on the edge band material is heated then applied to the edge of the laminate.
These adhesives are solvent or water-based, and either has one or a combination of the following:
- Ethylene vinyl acetate (EVA)
- Polyurethane (PUR)
- Polyamide (PA)
- Amorphous poly alpha olefin (APOA)
- Polyolefin (PO)
Edge Banding Pre-Mill: The trailing and leading edges are automatically sliced to length as the laminate exits the edgebander. Also trimmed are the top and bottom edges making the edging material flush to the laminate. Finally, after scrapping any surplus edging, the edgebander buffs the finished side.
Hot Air Edge Banding
Hot air edge banding is a recently developed method of adding edge banding to the substrate. Adhesives used with this method feature higher moisture resistance and heat compared with hot-melt glue.
Hot air differs significantly from hot-melt glue methods. There’s no adhesive applied to the inside edge of the edge banding material. Instead, hot air edge banding equipment activates a layer on the reverse side and welds the edge band to the laminate.
Comparing the finished products of hot-melt and hot air banding leaves zero surprises. There is a visible edge with the hot-melt method, while the hot air method leaves no edge.
Laser Edging
REHAU was the first North American supplier offering an adhesive-free laser edge banding option. Using a combination of a two-layer proprietary polypropylene and a laser creates a permanent, seam-free bond between the edge banding and the substrate.
Bill Knighton was an early advocate of hot air edge banding. Bill decided to feature the 4EVERedge™ as the standard for all RightAngle products.
Why?
The hot air method results in virtually invisible joins with a seam-free edge. The results increase the looks and protection of work surfaces and are fully recyclable, halogen-free, odorless, and neutral polypropylene material.
In Sum
What started as a stone surface thousands of years ago evolved into the work surfaces seen today.
As solid wood turned into engineered wood, the need to cover and protect edges progressed at the same time.
Something artisans spent time working with hand tools became less expensive for large production numbers.
Rather than being overlooked, edge banding became ubiquitous and a critical ingredient for quality work surfaces.
Edge Banding’s Edge was last modified: March 26th, 2019 by David Manney
Originally published at www.raproducts.com on March 27, 2019.
