Phenolic plywood is somewhat of a misnomer as it should more realistically be called “phenolic faced plywood” or “phenolic covered plywood.” The veneer core plywood itself isn’t made of phenolic; it’s generally made of birch. What makes it “phenolic” is that both surface veneers are soaked in phenolic resin before attaching them to the plywood. This creates an extremely stable, smooth, durable, highly water resistant and attractive surface.
These face veneers can either be wood (normally birch), like the core veneers or a thick paper. In either case, they are limited to the core plys under pressure, creating a permanent bond. The actual material doesn’t matter so much, as it is merely the carrier for the phenolic rosin. A thick layer of this is not necessary, as it is nothing more than a coating. If a thicker layer of phenolic were to be used, there would be no additional advantage.
Some people refer to phenolic plywood as “resin impregnated plywood,” although this is an inaccurate description. The only layers of the plywood which are resin impregnated in phenolic plywood are the two face veneers. All the other layers are normal hardwood veneers.
As with any other high grade hardwood plywood or marine grade plywood, phenolic plywood is made with a large number of thin veneer layers. Depending on the manufacturer, a 3/4” sheet of phenolic plywood is likely to have either 13 or 15 layers, although it could have even more. The combination of thin, consistent veneers and being a void-free product provide an attractive edge, when machined for industrial look furniture or store fixtures. It is a void-free product, as most cabinet grade plywood products.
What is Phenolic?
Phenolic was the first synthetic plastic resin, created in 1907 and used in the creation of Bakelite. Before other plastics existed, electric light switches and other electronic devices were molded out of Bakelite.
It is a thermosetting plastic, meaning that it sets into shape by a chemical reaction which produces heat. This allowed Bakelite to be molded in low pressure molds. In contrast to this, the majority of today’s plastics are thermoforming, meaning that they are melted and formed by heat. This requires expensive injection molding machines and molds which can withstand high pressure and temperature.
This difference explains how phenolic can be used to coat an engineered wood product, while more modern plastics cannot. Since it is molded to the plywood veneer as a liquid, it can soak into the wood fibers, bonding completely with them. To attempt to do that with a thermoforming plastic would require an adhesive that could bond to both the plastic and the wood (those are hard to find); unlike phenolic, which acts as its own adhesive.
Phenolic plywood is mostly manufactured in Scandinavian countries out of Scandinavian Birch. While it is used more extensively in the European countries, it is slowly gaining in popularity in the US, mostly for store and shop fixtures, where the smooth surface is a distinct advantage. It is somewhat more expensive than other types of plywood, roughly the same price as marine grade plywood, which is manufactured to similar specifications.
Since it is a mostly European product, don’t be surprised to find it offered in metric sizes or in five foot square sheets. However, most companies provide it in standard four foot by eight foot sheets for use here in the USA. There are also companies which provide 24” x 48” project panels, which are, at least, easier to ship. Another option is custom cut sheets, which are available online.
The phenolic surface provides several characteristics not found in other types of plywood products. Amongst the various types of plywood available, phenolic provides the toughest and most stable surface. The phenolic surface resists cracking and splitting from fasteners extremely well. Since the phenolic surface is extremely smooth, it is extremely low friction, making it an ideal surface where other wood pieces would need to slide over it.
Phenolic plywood is available in a variety of colors, although most lumberyards that carry it only carry one or two colors (black and brown are the most common). Nevertheless, the other colors can be ordered, especially if a large quantity of the plywood is needed.
Painting phenolic plywood is not recommended, as most paints do not bond well with the surface. Painting requires special paints, and even then, there is a chance that the paint will peel off the slick surface of the phenolic.
While the phenolic provides for a high degree of water repellency, this is not the same as to say that phenolic plywood is waterproof. Unlike MDO (Medium-Density Overlay) and HDO (High-Density Overlay), the resin is only on the two faces; it is not used as an adhesive for the veneer layers in the core of the plywood. Therefore, the plywood can still absorb water through the edges of the panel.
Proper finishing of the panel edges can increase the water repellency of the phenolic plywood panel, increasing the utility of this product in wet environments, such as commercial bathrooms (for partitions) and laundry rooms. Phenolic panels are often used to make furniture that is used in these wet environments, when a wood or plywood panel is desired, but high water resistance is needed.
This water repellency also makes it difficult to use phenolic plywood with adhesives. For adhesives to work, they need to be able to get a “bite” on the surface. The smooth surface resists adhesives extremely well. Therefore, it is recommended that anything built with phenolic plywood be assembled with fasteners, rather than adhesives. The only place where the adhesive would be effective is on the panel edges, as an additional support for the fasteners.
Use of Phenolic plywood
The most common use of phenolic plywood is in the making of jigs, fixtures, and cabinetry in the workshop. The low friction coefficient provided by the phenolic makes it extremely easy to slide work pieces across it when used as a tool table or fence.
Phenolic plywood is gaining popularity for use in specialized cabinetmaking applications. Although it does not provide for the same finishing options as regular cabinet grade or hardwood plywood, it does provide a smooth, clean, water repellent surface with consistent color. If you can find a good source for it, the phenolic itself is available in a variety of colors. This is giving rise to the use of phenolic for cabinetry in laundry rooms, garages and other work areas of homes, workshops and businesses.
For furniture or store fixtures, phenolic plywood can provide a rustic “warehouse” type of look popular in many casual clothing stores and some restaurants; while at the same time being extremely practical and attractive. The natural coloration of the panels eliminates the need for painting, while the stability and ruggedness insure that the fixtures will keep their good looks, without becoming easily dented, scratched or chipped.
Another growing use of phenolic plywood is in building furniture and fixtures for laboratories. The water and chemical resistance of the phenolic coating makes this a superior material over many others, while providing an attractive finished product. The edges can either be finished, covered with an edge band or covered with an edge board, depending on the specific application and aesthetics desired.
The rugged appearance and durability of phenolic plywood is causing it to be used for many other furniture applications; anywhere where durability is the prime consideration. School lockers, sports furniture and furniture for science laboratories are all being made out of phenolic plywood, outlasting the materials that were used previously.
A few contractors are also using phenolic plywood for the creation of cement forms, although this is not as common. While it cannot provide for the same long life as HDO, mostly due to its lack of total waterproofing; for short-term uses it is excellent. The smooth surface resists adhesion from the cement, without having to oil the forms. That provides a labor and cost savings over other material choices.
TigerFORM phenolic film plywood has been created especially for this application. It is apparently made from damaged phenolic plywood sheets, as the phenolic layer is repaired and sanded to ensure that the film is free of defect. While this makes it ideal for use in concrete forms, it would not be ideal for use in building furniture or store fixtures. The edges of this plywood are also sealed, with an oil-based paint, making it relatively waterproof.
Please note that when using TigerFORM for making concrete forms, you will need to seal any cut edges. The plywood core is not sealed or resin impregnated; only the surface and edges of the sheets are water resistant. Any cuts would not be.
Another specialized phenolic plywood is Metsä Wood. The phenolic overlay on this product contains visible texturing to help make it anti-slip. Intended for use as flooring in work platforms, scaffolding, warehouse, and other wet environments, this ¾” thick phenolic overlaid birch plywood is also used in the transportation industry, for truck and bus flooring.
Working with Phenolic plywood
Phenolic plywood can be a bit hard to find in the United States. However, it is worth searching for, especially for use in fabricating workshop fixtures and workbenches. If you want to make a router table or table saw extension, the use of phenolic plywood will provide you with an extremely smooth and stable top, with a low coefficient of friction.
Building things out of phenolic plywood is much like working with other types of plywood. The plywood cuts well with carbide-tipped saw blades and router bits, but you should avoid high speed steel blades and bits. The abrasive nature of the phenolic veneer layer is hard on blades, dulling them more quickly than if you were just cutting hardwood plywood.
Since the phenolic is a thermoset plastic, rather than a thermoformed plastic, it doesn’t soften or melt while being machined. This means that it will not distort from cutting and shaping. Most cuts will leave an extremely sharp edge, which should be sanded to prevent injury. The phenolic forms a fine dust, which can be harmful if inhaled into the lungs. Therefore, it is highly recommended to wear a respirator, whenever machining phenolic plywood.
It is not necessary to tape over a cut line, before cutting, like it would be with other types of cabinet-grade plywood. The hardness and uniformity of the phenolic face veneer resists the chipping common to thin face veneers commonly found on luaun plywood and cabinet grade plywoods.
Due to the hardness and density of the phenolic face veneer, this plywood provides a higher resistance to screw pull-out than you find with uncoated plywood. As mentioned earlier, this plywood should be assembled with fasteners, rather than being glued together. Edge gluing is possible, but will only provide limited structural strength. It is not recommended to only edge glue the panels, without the use of other fasteners.
The phenolic faces of the plywood should not be sanded, as they are very thin. This product is intended for use the way it comes from the factory, with no additional finishing to the surfaces. Only the edges need any finishing.
Since this is void-free birch plywood with many veneer layers, the edges can be routed, sanded and finished, providing a smooth industrial look which is popular in casual clothing stores, night clubs and other venues where a light industrial look is appropriate.
Sanding and staining these edges can serve to increase the contrast in the veneer layers, as the end grain will absorb much more stain than the side grain will. Once stained, the edges can be varnished, although varnish should be kept off the face veneers, as it will not stick well. Nevertheless, the combination of the multi-layered edge and very solid face colors is quite attractive.
If the design requires the plywood edge to be hidden, then it can be capped, either with a matching strip of phenolic material, with a self-adhesive wood plywood edging (apply with heat) or capped with a hardwood edge. In this case, the cap is usually “L” shaped, so that the extra material below the sheet can provide additional support, while giving the appearance that the board is thicker. This is common on counter and table tops. The top is sanded smooth with the face veneer.