The virtues of veneer

the_virtues_01_32One of the oldest forms of woodworking can add value to your work if you follow these simple steps

I've heard it said that the perception of truth is more real than truth itself. That's a dangerous concept to buy into, but nonetheless it does occur in the marketplace. Consumers are often presented ideas and concepts that are not completely accurate, yet through crafty marketing concepts, things eventually become gospel. Every day our court systems are filled with so-called experts either defending or denying the claims of corporate products. Veneer is one such product that has fallen into disgrace among consumers through bad information and poor product application.

Not always so

Veneering is one of the oldest forms of artistry woodworking. Its deep roots can be traced back to ancient Egypt. Wood was rare in the Middle East region at the time, which made veneer a great alternative. Because it provided versatility in application, veneer found favor among the well-to-do and its use continued throughout history. Craftsmen quickly figured out that veneer could open up new design possibilities. Expensive hardwoods went farther in the form of veneer, and the woods could be matched easier. This, combined with the use of marquetry (the art of inlaying wood), meant veneering was here to stay.

the_virtues_02_32Nothing could prove this fact more than the introduction of plywood. The first plywood sheets were used in the piano industry during the 1830s. It wasn't until the early 20th century that stock plywood panels became available. Then, with the advent of softwood plywood (designed primarily for construction), the industry standard was forever changed by revolutionizing the way buildings were constructed. Plywood has increased production for both the furniture and construction industries. Since most of us grew up in a world with plywood as the norm, we tend to forget it is veneering technology at its zenith. What softwood plywood did for the housing industry, hardwood plywood did for furniture. Prior to this mass production, craftsman had to veneer all panels themselves. Now, thanks to technology, we have readily available 32-sq.-ft. single sheets of premium hardwoods.

the_virtues_03_32So how is it that veneering acquired a bum wrap with consumers? It could probably be summed up as a result of misapplication and misrepresentation. And, in part, this is because veneered plywood became so readily available. It's the simple principle of supply and demand - the supply increases and the price decreases. Not only did the price of veneer drop with plywood, but also its perceived value as a viable woodworking technique.

the_virtues_04_32Most of veneer's history is found in the furniture "across the pond," where wood is more scarce. Because wood was such a plentiful resource in America, veneering was not seen as a necessity. Couple that with the fact that plywood was first produced here in the States and one can easily deduce how the market's perception of veneer was steered into the dump.

Options and advantages

So what does all this mean for today's craftsman? The same basic advantages our predecessors discovered ring true for us. Veneer simply offers the modern-day woodworker an alternative that should not be overlooked.

  • Material and labor savings: Most of us have figured out the huge advantages of veneer plywood. Think of how plywood allows us to do larger projects quicker and more efficiently. Material is not only in a large format size, but is generally ready to finish with minimal sanding and preparation. This, coupled with the fact that hardwood plywood is so readily available, makes veneering a smart business choice.
  • Grain and color matching: Wood is a product of nature. That means each piece will be unique. Some designs call for uniformity and consistency. This is difficult to achieve with solid wood, especially on large projects. A large public job I worked on a while back used several thousand square feet of bird's-eye maple paneling. Even if that much solid wood had been available, the taxpayers would have revolted against the state legislators. In addition, the architect insisted on uniformity of grain and color. Using veneer allowed us to purchase flitches from just a few trees that ensured the best chance of matching.
  • Large single panels: How many times have you needed to use a large panel, either as part of the design or an independent piece such as a passage door? Using solid wood requires milling component pieces and gluing them together. This involves matching and can be laborious (as previously mentioned). Veneering allows the craftsman to create large panels easily while maintaining design integrity.
  • Stability: Creating the likes of a large panel in wood should always be a concern. The organic properties of wood mean it's always moving. Wood takes on and releases moisture depending on environment and season. I was taught to never underestimate the power of wood movement. There are no glues or fasteners that will prevent it from moving. Therefore solid wood construction requires design that allows for movement. The beauty of veneering is that the designer has more latitude in what can be done with the wood. So long as the veneer has been bonded on a stable substrate, its movement is minimized.
  • Inlays: I've never met anyone not intrigued by marquetry or wood inlay. The usual first instinct is to run the hand over the surface as if not convinced that the dissimilar materials are flush. Inlays and marquetry are veneer-friendly. The thickness of the material makes it easier to work with. And, in the case of marquetry, it is necessary in order to achieve the level of detail required. Inlaying veneer is also a safer design decision than using thicker wood. Designs often call for pieces being placed perpendicular to each other. In solid wood this would almost guarantee failure since wood moves at a different rate across the grain than with it. Because veneer is thin, this concern is virtually eliminated.

Materials and technique

Getting back to the consumer's poor quality perception of veneer: Are their concerns legitimate? Yes, primarily because of the improper use of material and poor technique. Familiar veneer failing would include delamination, telegraphing substrate, ugly edgebanding, poor seams and sand-through. Most of these issues can be eliminated through education. In other words, the proper use of materials and technique.

the_virtues_33Let's take a look at some of the basics. Two things define a successful veneering job: design and execution.

Although many projects can be designed to incorporate veneer, the application of veneer demands that it be integrated into the design. For instance, edgebanding with veneer is a very common and accepted practice. However, you must be careful where those edges are located. The exposed vertical edges on paneling rarely experience regular abuse, so veneered edges hold up well. Even cabinet-door edges, which do experience regular handling, are not typically subject to radical abuse because their edges are on a vertical plane. When designing for veneer on horizontal planes, the designer must make the assumption the piece will encounter heavy use.

Veneering is very different than using solid wood. There is really no joinery involved except in the case of splicing the veneer together. The joinery required to hold the piece together is always housed within the solid wood or substrate. Therefore, questions about how the veneer will interact with the joinery must be addressed. For instance, will the veneer cover the joinery? If so, you need to ensure it's not a joint that requires room for expansion and contraction as in solid wood joinery. Or, if it's covering a wide solid wood edge on a particleboard substrate, have you allowed for the potential of the solid-wood edge joint telegraphing through? Veneer is often the focal point of the design, especially when figured woods are involved. However, when it comes to the assembly and structure of the piece, it plays a supporting role only.

When doing veneer work you need to be able to effectively splice your pieces together. With today's technology offerings there are specialized machines designed to do most everything. If you plan on doing a lot of veneer work, you may want to invest in a machine dedicated to this task of joinery - a splicer. But for the rest of us who don't need to do production veneer work, there are plenty of alternatives. A straight edge and sharp knife, a router and jig, and a handheld veneer saw and veneer cutter are all very effective and affordable means to cut straight edges.

the_virtues_34Once pieces are cut, you need to join them together before gluing. Again, production shops use a stitcher; either handheld or stationary. A less expensive option is using veneer tape. Veneer tape has an adhesive on one side that is applied to the face (or top) of the veneer and does a great job of holding pieces together. It typically has holes in the surface, which minimizes the amount of tape you have to remove after the piece comes out of the press. You don't need any special equipment to apply the tape, but a dispenser with a water reservoir that activates the glue when pulled through is highly recommended.

Of equal importance in achieving a successful veneering job is selection of proper supporting materials and the execution or technique in applying those materials. First, let's talk a little about glue. There are many types of glue that can be used. The traditional hide glues, PVA (polyvinyl acetate or the common yellow and white glues), resorcinol and urea resin, to name a few. Because the properties and applications can be so different, there is no single glue for every application and every shop.

Glue basics to know:

  • Hide glue is old school. It was the choice of use for "hammer veneering," a process that does not require clamping.
  • PVA glues are easy to apply (no mixing) and set up quickly.
  • Resorcinol glues require mixing, are waterproof, have a longer setup time, but leave a dark glue line and should not be used where appearance is important.
  • Urea resin is a popular choice for today's veneer craftsman. It's a two-part mix, has a reasonable working time, is highly resistant to water and provides a rigid glue line.
  • Many shops also use contact cement, which I hate to even include in the subject of veneer. Its popularity is derived solely from the fact that it creates an instant bond, therefore not requiring a press to provide even pressure. However, the glue line is not rigid since the glue moves like rubber. The only type of veneer that contact cement should even be considered for is with manufactured veneers, in particular those with phenolic backing.

Without a good means to clamp veneer during gluing, you'll never achieve good results. The old-school woodworking standard was a hand screw veneer press. The screws moved cauls in place that applied the pressure needed to the veneer panel. These actually worked quite well. I used one in my shop years ago, but found I was not only limited in what I could do, but it took up a lot of space when it wasn't being used. Production shops use either hot or cold presses that allow the fabricator to glue up several panels at a time very quickly. For the small shop, the best option is a veneer bag. These provide the fabricator with many options. Flat and curved work is easily performed. Veneer bags utilize a venturi pump, which sucks the air out of a bag creating a pressure reaching close to 2,000 psi. The beauty of the veneer bag is every square inch inside that bag is being excavated. This means you have a much better chance of getting even pressure onto the entire piece.

Properties of veneer

Veneer is available in what I classify as raw or manufactured. Raw veneers are purchased as they come out of the mill. When a log is sliced, each piece is stacked upon the other and sold as a flitch. Raw veneers are going to be thicker than manufactured veneers. Thicknesses vary, but the average is between 1/36" to 1/50". Because they are purchased as they come off the log, edges need to be straight-lined and joined together with a stitcher or tape before gluing up. Although this is a more labor-intensive process than when using manufactured veneers, the designer/builder has more options. Raw veneer is what you'll use for marquetry, inlays and for creating the best grain patterns.

 

Don’t blame it on the veneer

Not long ago, a contractor friend of mine brought an exterior door by the shop that he wanted repaired. A remodeling project he was working on had gone over its allotted time frame because of this problematic door.

Apparently the door had gone back to the manufacturer for a delaminating problem on two occasions. On its second trip back to the house, the door fell out of the contractor’s van and got a good case of road rash. My poor friend was so distraught and rushed to get the job done; he asked if there was any way it could be repaired.

The veneer was surprisingly thick, but not thick enough as we ran it through the thickness sander to remove the scratches. I suggested buying a new door, but the lead time did not bode well, so I reluctantly offered to re-veneer it for him. A day after he picked the door up from me, he said he sanded through the veneer. The second time, I told him not to do anything to the door except finish it.

The point? My friend did nothing but curse the use of veneer. The veneer didn’t originally delaminate on its own (it was a glue or moisture issue). The scratches that couldn’t be sanded out were simply the result of not securing a load, and sanding through the veneer was from not understanding the properties of the material, not because it was the wrong material being used.

— D.G.

Manufactured veneers would include those laid up as plywood products and veneers that have been made into 4x8 or larger sheets. We don't typically think of plywood as veneer, but most of the same considerations we apply to veneering are relevant. The main difference is it's already on the substrate panel. We're not discussing plywood right now, but this is a good place to discuss substrates for veneer. Looking at what plywood manufacturers use for a core is a good indicator of what the small fabricator should use. Veneer core is really not going to be a viable option for the small shop. Particleboard and medium-density fiberboard are the most common choices. Both are stable, inexpensive, come in various size and thickness options and are readily available. For thicker components such as passage and entry door stiles and rails, laminated solid wood cores can be purchased.

Manufactured sheet veneers are overlaid on a paperback, phenolic back, or another piece of veneer, which is called a "two-ply veneer". These veneers are real time-savers when it comes to veneering. Splicing is eliminated, allowing the fabricator to get right to the business of gluing. They are also very stable allowing the user to apply veneers in situations where raw veneers would fail. However, one must specify these carefully. Because the actual wood veneer is so thin, they cannot be sanded, eliminating most splicing or inlay applications. They're also not going to be as durable as raw veneers when used in horizontal designs. Where these veneers really shine is basically in any application where you would normally specify plywood, but are unable to because of the situation. This could include an existing condition (over a surface you did not fabricate) or a field applied application where it's impossible to use a press.

When working with veneers, the designer also needs to be aware of the different ways veneer can be laid up on a panel. The most common layup is book-matching the veneers. This is where the leaves are flipped open like a book page to create a mirror image on the other side of the spliced joint. This technique creates a pleasing symmetrical pattern. When you flip the veneers over in a book-match application, one piece has the bark side exposed and the mirror piece has the inner tree side exposed. Differing sides of the log reflect light and will accept a finish differently. This can cause a striping effect. To eliminate that, along with creating a different pattern in the wood, specify slip matching. In slip matching each leaf is placed side-by-side, keeping the same face up. This creates a repeating pattern on the panel. These two layup techniques are the most common, but there are many others (end matching, herringbone, starburst, etc.) to consider.

In-house or outsource?

 

Vacuum bags are a wise investment

I’m sure most professional woodworkers are familiar with vacuum bags. For those who aren’t, you need to understand this: if you’re planning on doing veneer work, you’ll need to buy a vacuum bag system. They provide the simplest means to do quality pressing.

 

You’ll soon discover how much grief will be eliminated when you don’t have to worry about your pressing system.

 

Vacuum bag technology is fairly simple. It’s made up of a vacuum bag (constructed of vinyl or the more durable polyurethane bag) and a pump. The veneer and substrate is placed in the bag and sealed. The pump, which is attached to the bag via a hose, sucks all the air out of the bag, causing the bag to collapse around the wood project inside.

 

In other words, as the vacuum is created, atmospheric pressure comes down on the work in the bag. This creates a force close to 2,000 lbs. per square inch. This incredible force, combined with consistent pressure on all sides, greatly simplifies the gluing operation. It can be used on both flat and curved work. Because of the even pressure, the standard male and female matching cauls used in curved work are eliminated. Only the single female form is needed, which further saves the professional time while increasing consistency.

 

Basic models include a bag and pump, while the more elaborate systems are table-mounted with hinged lids, making access easier and increasing productivity.

For information, visit www.vacupress.com and www.qualityvak.com.

— D.G.

Just like any other process that gets run through a shop, the woodworker needs to determine whether to do the veneer work himself or outsource it. There are no easy answers to this question. Veneer work can be both simple and very complex. The best thing to ask is whether you need or want to do the work. Outsourcing veneer work makes sense if you have a large square-foot quantity required, or if you don't have the time, resources or ability. Doing it in-house is a good way to ensure quality control. The key is making sure you do it correctly. This also means you must have the right equipment/tooling to do the work properly. There are many techniques touted in the marketplace that promise quick and easy veneer work. It's up to you to make sure they will indeed hold up. I've seen dozens of veneer jobs gone bad because of fabrication inexperience and improper use of materials.

I personally find veneer work very enjoyable and stimulating, yet it is sometimes still quite frustrating. It's not the type of work to hurry through. It requires patience. It's one of the best ways to ensure wood color and grain matching in a piece. It does require a different approach to design, which obviously affects how the end product appears and functions. Therefore, veneering is not conducive to every project. However, custom veneering could be specified more often. It's a great way to showcase your prowess as a professional woodworker and the inner beauty of the wood itself.

David Getts is the owner of David Getts Designer Builder Inc. in Seattle.

This article originally appeared in the August 2009 issue.

Comments (1) Comments are closed
1 Friday, 30 April 2010 23:08
George F Heagle
A very good introduction article to veneering and the process. I do bleieve there is one technical mistake regarding the vaccum press pressure....Most pumps pull about 25 to 27" of Hg depending on sea level....The atomosphereic pressure produced in such a vaccumm is at best 15.5 to 18 psi not 2000psi. More than enough pressure to hold glued veneers until they set. Thanks for the article