Magic in engineered wood: composites to save trees, add strength, conserve energy.

"Magic has truly occurred with the development of the wood composites industry."

Much has happened in the field of engineered wood, or composites, over the last 40 years. Materials are now manufactured in quantities that once were only dreams. It can be estimated that in the United States alone, roughly 21 million tons of composite products are manufactured annually out of previously unusable raw materials.

The composite products part of the forest products industry is positioned to provide vitally needed building materials and other materials to the world society at economic levels. High technology should make it possible to supply reasonably priced composites. In addition, composites have been responsible for greater use of the wood raw materials and this trend should increase. Indeed, there is magic at work.

"Composites" is a word easily misunderstood. In this discussion, composites are defined as materials that have the commonality of being glued or bonded together. Thus, glue, resin, or another binder, is an important part of producing quality composites. My definition is any pieces or elements of wood that are glued together. This description covers a multitude of products and I use it to avoid the use of trade names that tend to confuse people. An even more recent term is "engineered wood."

Most of this industry has been developed using what were previously waste wood residues or little used or non-commercial species. Very little raw material is lost in composites manufacture. Almost half of the industrial materials manufactured in the United States are wood products. However, only about 4 percent of the total energy needed to manufacture all industrial materials is used by the forest products industry - a considerable energy conservation.

Coming to terms

Throughout the world there seems to be great confusion on composite terminology. I use the term "composite" simply as any wood material made of smaller pieces and glued together.

Within this family of materials, several subgroups develop naturally. The differentiation between products within a subgroup could be on the basis of properties or uses, rather than the type of particle or fiber used. For example, products could be roof sheathing, furniture panel, lumber, etc., or by material description. Most of the present-day composite materials are listed below:

* Plywood

* Blockboard 

* Fiberboard (non-compressed, insulating board, and compressed, hardboard)

* Medium density fiberboard (MDF)

* Particleboard 

* Waferboard

* Oriented strand board (OSB)

* COM-PLY[R]

* Molded products of particles, flakes, or fiber

* Inorganic bonded (cement or gypsum)

* Laminated veneer lumber (LVL)

* Oriented strand lumber (OSL), includes Scrimber and Timberstrand[TM]

* Parallel strand lumber (PSL) - Parallam[TM]

This list can be expanded easily to include all types of laminated materials (overlaid panels to beams), edge-glued panels, components (I-beams, T-beam panels, stress-skin panels), and, eventually, to large molded building parts or even buildings.

A certain group of the above composites, namely, plywood, OSB, variations of structural composite panels, glued laminated (Glulam) timber, I-beams or joists, the different variations of OSL and PSL, are now being called engineered wood products or EWP. As with almost all of the composites, these materials can be engineered to various specifications (in this case, structural specifications) taking full advantage of wood's inherent properties while at the same time improving upon these properties. For the most part, the structural specifications, standards, and certification for EWP materials are being covered by the APA - The Engineered Wood Association (formerly the American Plywood Association). Some companies have elected to use testing companies such as PFS/TECO for certifying their products. 1-joists are presently covered by individual companies gaining code acceptance for each operating plant.

Composite Panels

Softwood Plywood

Plywood should be well known by those in the industry. Most of the modern-day composites originated in North America, starting with softwood plywood in Portland, Oregon in 1905.

Softwood plywood dominates the North American structural panel market. Significant. improvements in production resulting in reduced production costs, have enabled the industry to increase production and remain competitive with OSB. In the past few years, however, a reduced timber supply in the western United States as well as increases in veneer log prices have caused a considerable number of plants to close. Plywood plants are attempting to produce mostly higher-value products rather than sheathing (basic building panels), leaving much of the sheathing market to lower-cost OSB.

Hardwood Plywood

Unlike softwood plywood, which is used mostly for structural applications, hardwood plywood is used both structurally and as decorative panels. This is a product that can be traced back to ancient times.

Blockboard

Blockboard is often overlooked today, but its old technology, or variations on the old technology, could provide panel-building products in many places. Blockboard panels (made with strips of lumber in the core with crossbands of veneer or hardboard faces) are produced with glue edge jointing the core lumber strips, thus, the adhesive cost can be quite low. About 14 new plants have been built in Europe producing blockboard with thin lumber faces rather than veneer. Blockboard is used for paneling, furniture, and extensively for concrete formwork in Europe.

Particleboard

Particleboard is a generic term for a panel manufactured from lignocellulosic materials (usually of wood), primarily in the form of discrete pieces or particles, as distinguished from fibers, combined with a synthetic resin or other suitable binder and then bonded together under heat and pressure in a hot press by a process where the entire interparticle bond is created by the added binder. Other materials may be added during manufacture to improve certain properties.

The basic raw materials for particleboard are plant residues or low-quality logs. Some recycled wood material, where it is economical to use such a substance, is now part of the raw material supply. New plants, based on straw, also are starting up in North America. Bagasse (sugarcane stalks) also has been used for board in a few countries.

Particleboards are further defined by the method of pressing. When the pressure is applied in the direction perpendicular to the faces, as in a conventional multi-platen hot press, they are defined as flat-platen pressed; and when the applied pressure is parallel to the faces, they are defined as extruded. Particleboard remains the world's dominant furniture panel, although considerable amounts of its production also go into structural applications such as manufactured home floors, roof sheathing, wall panels, stair treads, and for house floors elsewhere in the world.

The first platen-pressed particleboard plant started operation in Dubuque, Iowa, in 1933. This small plant ran until 1942. A larger commercial plant commenced operation in Germany in 1941. The prodigious development of the particleboard industry started in the 1950s.

Extruded particleboard was developed in Germany by Otto Kreibaum in 1947-49. Numerous plants were built throughout the world including the United States. However, low production capacities and some board physical property limitations kept this type of process from becoming a major product line.

At one plant being built in the 1950s, the investors wanted to see the plant in operation before it was actually ready to run. The problem was that the resin-addition system was not in place. But to satisfy the investors, the engineering firm ran the plant, not knowing what would happen in the hot press. Most of those in the industry today know, of course, that the moisture in the mats being pressed into board turns to steam. The resin found normally in the mat cures and holds the board together when the press is opened at the end of the pressing cycle. However, in this particular demonstration, run without resin, all of the boards, in the multi-opening press blew apart as the press was opened.

This "explosion" frightened the work crew so much that it took considerable coaxing to get them back into the plant.

MDF

MDF is a dry-formed panel product manufactured from lignocellulosic fibers combined with a synthetic resin or other suitable binder. The panels are compressed to a density of 0.50 to 0.80 specific gravity (31 to 50 lb/[ft.sup.3]) in a hot press by a process in which the entire interfiber bond is created by the added binder. Other materials may be added during the manufacturing process to improve certain properties. MDF production started in Deposit, New York, in 1966. Arguments also can be made that the first MDF was made in a plant in Oakridge, Oregon, or in one in Meridian, Mississippi.

Many new MDF plants have been erected recently and many others are in the planning stages. There are now over 100 plants worldwide. The plants produce thin and thick boards. Thin MDF is usually produced by continuous presses. However, most of the newer plants producing thicker panels also use the newer continuous presses.

A wide variety of raw material types can be handled in an MDF plant. These types range from pulp chips to planer shavings to plywood trim to sawdust. Other non-wood materials such as bagasse also make excellent MDF.

MDF lends itself well as a substitute for clear lumber. It does not have a grain structure, but finishes and overlays can be used effectively to provide a product that, in appearance, looks like wood. A considerable amount is now used for moldings or millwork, replacing solid lumber.

Learning how to press board was and is, even today, an "interesting" experience. In the Meridian plant, the learning experience included blowing a pressload of boards so severe that the windows of the plant were blown out. One person commented that this was the greatest press blow in panel board history. There was also a problem in this plant with boards sticking to the press platens. A mold release was found that cured the sticking problem for a while - perfumed Cashmere Bouquet soap. This left everyone in the plant smelling sweet went they went home.

Hardboard (compressed fiberboard)

Hardboard is a generic term for a panel manufactured primarily from interfelted lignocellulosic fibers (usually wood), consolidated under heat and pressure in a hot press to a density of specific gravity 0.50 (31 lb/[ft.sup.3]) or greater. Other materials may be added during manufacture to improve certain board properties. It was first developed in 1924 by W.H. Mason and the first plant was built shortly thereafter in Laurel, Mississippi.

Wet-process hardboard also continues to be an important panel product worldwide. However, the need to clean the waste water from the manufacturing process has in recent years been of concern. Some methods of utilizing it, such as for irrigation, have become, under stricter environmental regulations, against the law in some countries. Work on developing enzymes and bacteria for cleaning water could be an important development for wet-process hardboard.

Wet-process hardboard has been impacted in the United States by the development of OSB siding. Siding has been the major market for hardboard in the United States. Hardboard in the United States is also being used as a substitute for solid wood in trim applications.

Expansion of product lines includes roof-covering material in the form of tiles or simulated wood shingles or shakes. Such hardboard is untreated and is being manufactured and used in South Africa as well as the United States.

Dry-process hardboard is now becoming quite confused with thin MDF. The dry-process board is bound together with synthetic adhesives, the same as particleboard and MDF. Research conducted in 1945 by the Plywood Research Foundation (established by the forerunner of today's APA) started this production process.

The board usually has poorer properties under wet conditions than does wet-process hardboard because the hemicelluloses, with their affinity for water, are retained in the furnish rather than partially washed away as in wet-process hardboard. However, a significant development of dry-process hardboard technology (some would argue this is MDF) is the production of door skins. This development will be discussed under molded materials, but it is a major product line in the United States.

OSB/Waferboard

Waferboard was first produced in 1955 in Dover, Idaho, in a plant that ran into the 1970s. The process invented by James d'. A. Clark used large flakes, called wafers, bonded together into the final panel.

Generally made from low-density hardwoods, mostly aspen, waferboard was well accepted in several sheathing applications. The first large production of waferboard occurred in Canada starting in the 1960s. Further production of waferboard in the United States didn't happen until the late 1970s. Waferboard has now been replaced mostly by OSB.

OSB (oriented strand board) panels are made from compressed strands lined up (oriented) and arranged in layers (usually three to five) that are placed more or less at right angles to one another. At times, the core layer may be of random orientation. Panel stiffness and strength approaches that of plywood.

OSB came to prominence in the 1980s as the technology developed for manufacturing this product. Numerous individuals and companies contributed to the development of the OSB industry. Most of the original work is attributed to the Elmendorf Research Corp. of Palo Alto, California. The Louisiana Pacific Corp. was the first company to build many OSB plants.

The panels are almost all used in structural applications in the same way as plywood (an exception is the phenolic paper overlaid OSB that is used for siding). There are now 63 operating plants, with 16 others due to come into production before 1998. Almost all of the plants are in the United States and Canada. Others in operation or being constructed are in France, Venezuela, Ireland, and Scotland. Great interest in this product is being expressed in Southeast Asia.

Most OSB is now made with 3-inch (75mm) long or longer strands in the surface layers. The core may be of smaller strands and may or may not be oriented. The OSB segment of the industry has become an important part of the structural panel business in recent years, now comprising about 30 percent of the structural panel market.

The industry has been developed on low-density hardwoods such as aspen; however, other species such as southern pine, lodgepole pine, jack pine, and Scotch pine are being used.

High-density species are still difficult to use because boards produced from such species are also quite high in density. These boards are difficult to handle, cut, and nail, and they are more expensive to ship.

Molded Materials

Molded materials of fiber or particles have a long history in the industry, particularly in western Europe and in the United States. Molded parts for the automobile industry have taken an increasing share of the market formerly served mostly by plastics. Combinations of wood and plastic fiber have made it possible to produce inside car door panels with deep draws or impressions - an impossibility with wood fiber alone. As many as 12 such panels are now going into some models of U.S. cars. These panels are overlaid with various plastic foils. The high strength-to-weight measure of wood fiber moldings has made their use quite attractive. Another successful molded product is pallets.

In recent years, an important new molded fiberboard product has been developed, namely, door skins. Many plants now produce door skins and their manufacture has attracted worldwide interest. Door skins are thin MDF or dry-process hardboard panels molded (pressed) into one of many panel door patterns. These skins (one on each side) are then glued to a wooden door frame to make up the final door. These doors, which replace solid wood doors, are a major product line.

New lumber or composites

The decreasing quality of the world's forests and the amount of timber available for producing either conventional lumber or high-quality lumber have led to a tremendous interest in producing composite lumber-like materials. Research has shown that such materials can be made and, indeed, plants are now producing these lumber-like products.

The products include laminated veneer lumber (LVL), COM-PLY [R], parallel strand lumber (PSL), and OSL (Timberstrand [TM]). As of 1995, LVL has become the most important construction material.

It's clear that the today's realities and the possibilities for the future for engineered woods are many. When I started in the wood industry 40 years ago, the timber barons of the time laughed at the composites developments - indeed scornful words were used. They were lumbermen and were just starting to accept softwood plywood.

But times have changed: Without the composites of today, the forest products industry would not be what it is today. As I have said many times, "Magic has truly occurred with the development of the wood composites industry."

RELATED ARTICLE: WOOD FOR THOUGHT

The volume of new wood created by one year's growth of the trees in commercially operated American forests is equivalent to a flooring 1 inch thick, 10 feet wide, and extending 238,857 miles - from the Earth to the moon.

Wood Products 1943

RELATED ARTICLE: Hardboard: The Accidental Invention Richard Lumsden 

Necessity may be the mother of invention, but a little luck goes a long way too. That's what William H. Mason found out in 1925 when he forgot to shut down his laboratory equipment during a lunch break. He was trying to press wood fiber into insulation board, but what he found when he returned was a durable, thin sheet that would launch a world-wide industry - hardboard. Today, American hardboard manufacturers produce more than 7 billion square feet of Mason's accidental invention each year.

Mason began with a simple problem: Find a use for the huge quantities of wood chips that lumber mills discarded as useless waste. Arming himself with a blowtorch, an 18th-century letter press, an old automobile boiler, and the ingenuity to create useful homemade contraptions, Mason became the first person to successfully break down wood and put it. back together using only the wood's natural binders. Mason's hardboard product was manufactured and sold by the company he helped found Masonite Corp.

In the early years, Masonite and its competitors thrived by selling hardboard as a commodity in plain brown panels. As new production methods were developed and patents fell, the industry widened. Industry leaders became those who were able to turn plain board into prefinished products.

The growth of competition was the best thing to happen to the hardboard industry since Mason's "accident." Hardboard is versatile and lends itself to processing, so today's hardboard manufacturers everything from wood-grain panels to intricately cut or molded furniture components. Hardboard may be perforated, fill coated, primed, painted, and precision cut with lasers. A far cry from Mason's early invention, these value-added products employ state-of-the-art equipment to help furniture and cabinet makers save time and money.

Product improvements continue today as hardboard manufacturers expand their research efforts. But who knows - the next great hardboard application might come about while researchers are out to lunch.

RELATED ARTICLE: Woodworkers Gobble Up More Panels

The fact that today's particleboard and medium density fiberboard panels are far superior to those of only a few years ago - let alone 25 years ago - has not gone unnoticed by manufacturers of furniture, cabinets, store fixtures and other wood products, who each year incorporate greater amounts of panels in their products.

The accompanying charts, originally published in WOOD & WOOD PRODUCTS January 1995 issue, tell most of the story. Between 1980 and 1995, annual consumption of MDF increased more than three-fold, with further gains expected by industry analyst Resource Information Systems Inc. as new North American MDF plants come on board within the next few years.

At first glance, the story for particleboard seems less dramatic. Overall consumption of particleboard only increased by one-third between 1980 and 1995. However, what this chart does not show is the tremendous swing for particleboard demand from underlayment uses to industrial uses like furniture and cabinets. According to the National Particleboard Association, in 1980 industrial shipments accounted for just about 51 percent of all the particleboard that was shipped from U.S. mills. In 1992, industrial use accounted for 83 percent of the total demand.

RELATED ARTICLE: Particleboard Has Come a Long Way, Baby

The first U.S. plant to take advantage of a new, German-engineered system of making particleboard using an air classifier was Willamette Industries' Duraflake plant in Bend, Oregon, which shipped its first TECO certified board in December of 1960.

As recalled by Tom Buglione, long-time Duraflake plant manager, now retired, Willamette's decision to jump into the particleboard business was based on its abundance of planer shavings, which nobody in the United States was using for particleboard at the time.

"There were a few plants on the East Coast making particleboard, but they were using pulp wood chips and other, larger pieces of wood. Willamette wanted those pieces for use in their paper plants, but had tons of fir planer shavings readily available," Buglione said.

According to Buglione, Willamette shipped its several test loads of Douglas fir shavings to Germany for tests. The tests, conducted by the press manufacturer Bison, produced a fine board and plans for Duraflake were up and running.

But that's not to say everything went smoothly. It took constant tinkering before the plant was able to produce a quality product, and even that was a far cry from the particleboard of today.

In fact, Bill Affolter, salesman for Duraflake, was questioned about the properties of the new board at a company Christmas party. Duraflake had made little puzzles for the party by cutting a small panel with a jigsaw. Partygoers found their dinner partners by matching jigsaw pieces. Affolter was seated next to a dyed-in-the-wool plywood man, who took a look at the new product and said, "Well, what's going to happen when this stuff gets wet?"

Affolter assured him the material could take a bit of moisture and dunked a piece in his coffee cup to prove his point. Much to his chagrin, the particleboard disintegrated in the coffee! But the product rapidly improved and soon Duraflake was selling the product to the building and furniture trades.

Dr. T. M. Maloney is the Director of the Wood Materials and Engineering Laboratory at Washington State University. The information in this article has been developed and reported by the author mainly through his book Modern Particleboard and Dry-Process Fiberboard Manufacturing, a number of papers and encyclopedia chapter.