Wood and wood products in the cabinet industry

 

There are a lot of products on the market today for the cabinet industry.  Cabinets are usually made from some solid woods, some plywood products, and some particle board, or fiber board products.  Let me take a minute and talk about all these products and their uses.

 

Solid woods: 

When we say “solid wood” we are referring to woods as they are harvested from the tree, or cut in planks from the log.  There are “soft woods” and “hardwoods” in this category.  However, these categories may be misleading as some “hardwoods” are not hard and some “soft woods” are quite hard.  The term “hardwood” refers to species of trees that are deciduous (that drop leaves), and “softwood” is in reference to lumber cut from conifers (pine, spruce, fir etc.)

 

 

Many of these woods are appropriate for cabinet construction.  Some solid hardwoods we commonly use are: Oak, Maple, Cherry, Hickory, Beech, Ash, Elm, and Willow.  Solid softwoods we use include: Fir, Cedar, Pine, and Spruce.  These woods have different characteristics and looks, and there may be different “grades” of each wood available.  You should talk with your cabinet provider as you choose a wood for your home to insure you find a material that will meet your particular needs.

 

Solid woods are generally used to build the parts of a cabinet that show.  The doors and drawer fronts are usually made from solid woods.  Face frames (when they are used) are also built from solid wood.  Sometimes end panels (the sides of cabinets) are also solid.  They may be a solid slab, or panelized, or an applied false door.

 

Examples of solid woods: Poplar, Alder, and Hickory

Solid woods are not generally used as shelves or other parts of the cabinet box.  This is for several reasons.  The most important of these is material stability.  Solid woods, as a natural material, are not dimensionally stable.  What this means is that over time seasonal changes in temperature and humidity can change the size of a piece of material by as much as 5%.  Solid woods have a circular annular ring grain structure to them.  These grain patterns are what make solid woods beautiful, but are also the reason solid woods tend to warp, twist, cup and curl with environmental changes.  These fluctuations lead to joint failures and possibly cracks in the material itself.  Plywood and other engineered products are much better suited to build cabinet boxes.

 

Plywood:

Plywood refers to wood that is layered together to form sheets.  Plywood can be made from many different materials and in many different grades (qualities).  Usually layers alternate in direction of the grain.  For example, the first layer runs with the length of the panel and the second layer runs with the width.  This alternating grain helps to enhance the woods dimensional stability (it doesn’t change size or shape as easily).  It also gives the panel strength in both directions.  Generally plywood has an odd number of layers so that both exposed layers have grain running the same direction.  The layers between the exposed layers are called the “core”. 

Typical domestic plywood:

1/2” Natural Maple rotary cut

Notice 3 core veneers and 2 outside finish veneers

At Chateau Mill we use some high quality plywood as the material of choice for most of the cabinet box.  For parts that are exposed in the finished project (exterior parts or interior parts that are not covered or are covered by glass), we use a plywood that matches the face and door wood.  We try in all instances to find sheet goods with a veneer core for these applications.  In some instances there are not veneer cores available in some species or grades.  For example, we may have a hard time finding a sheet of select cherry plywood with a veneer core and we are forced to the next best option of using an MDF core sheet (more on MDF later).  We have gone to great lengths in many cases to persuade mills who produce plywood to “lay up” sheets with veneer cores.  Typically they will do this but it usually involves a delay in delivery and a minimum quantity.  We decide on a case by case basis the best option for our customers. 

Baltic birch ply: 1/4” = 5 ply;1/2” = 9 ply; 3/4” = 13 ply

For interior construction (those parts that don’t show from the outside of the cabinet) we use Baltic Birch.  Baltic Birch is unique in the industry.  Much of it is sold in 5 foot by 5 foot sheets instead of the usual four by eight.  It is also manufactured in a different way than most domestic plywood.  This unique birch ply has several advantages.  First it is composed of more layers per inch than domestic plywood.  3/4” Baltic Birch has 13 plys (or layers).  Because of the increase in the number of layers, the product is more rigid than products with fewer layers.  Also all the layers are birch.  Many other kinds of plywood have “fillers” that are not the same wood as the exterior.  It also is void-less.  When a flaw in the material, such as a knot hole, is found during the manufacturing, the flaw is punched out and replaced with a solid patch, even on the interior layers.  This means the product will present no voids (spaces) no matter where you cut it.

 

In general, plywood is a structurally superior compared to particle board or fiber board products.  It is more rigid and it’s structural integrity allows it to hold fasteners like screws and staples better than these other products.  At Chateau Mill we prefer to use plywood over any particle board or fiberboard product whenever possible.  We feel that this gives our customers a better product that is stronger in the panel and stronger in the joints.

Particle board:

Every product available to cabinet manufactures has it strengths and weakness, and so it’s appropriate use.  Particle board panels are very flat, and the most dimensionally stable material.  Because of the small particle size, there is no internal stress in it to cause it to warp or twist.  If properly supported, particle board will remain flat and dimensionally stable.  At Chateau Mill we use particle board as a substrate for laminated counter tops (like Formica®).  The cabinets below the counter properly support the product, and it is very flat allowing for a smooth counter top in the finished product.

Melamine clad particle board is available in many solid colors and wood grain prints

Raw particle board like we use to build laminated counter tops

Weaknesses of particle board are lack of linier grain structure, and water absorption.  Because of the water absorption problem, raw particle board is rarely used in cabinet construction.  In the case of laminated counter tops, high pressure laminates (like Formica®) are completely water proof and thus protect the particle board panel from swelling from water absorption.  Many coated particle board products are now on the market that also offer protection.  For example, melamine coated particle board is extremely water resistant.  Water cannot penetrate the melamine, and unless the melamine coating is damaged or removed, the product is safe from water damage. 

Many cabinet companies build the entire cabinet box from melamine clad particle board.  Care must be taken in these instance to seal the exposed edges in joints especially in an application where exposure to water is a possibility.  Melamine coatings are also helpful to cabinet builders because it means that the interior of the cabinet box made from particle board coated with melamine is pre-finished and requires no coatings of lacquer or varnish.

 

The lack of linier grain structure in particle board is of greater concern.  Because of the small size of particles in the product, it is more likely to break, or at least deflect (sag or bend) under a load, when compared to plywood.  Because of this, fastening methods, including screws, nails, or staples are more likely to fail.  Joints cannot be as strong.  Particle board is pressed into a panel by exterior force, and so has it’s hardest material on the exterior surface.   If this hard shell is disrupted by a dado cut, the structural integrity is further compromised.  Because of this, most manufactures do not use dado or rabbet cuts in their corner joinery.  Dado joints have three glue surfaces and rabbet joints have two.  Butt joints that are required with this type of material have only one glue surface and so can never be as strong  as a dado or rabbet joint in plywood or solid wood.  Beyond this, particle board is heavy, much heavier than plywood of the same dimension.  The first “load” a cabinet is required to hold is it’s own weight.  Overall weight capacity of  particle board cabinets is reduced by it’s own weight first and then by weaknesses in material structure and joint strength. 

 

Are the acceptable cabinets built of melamine clad particle board?  Well, certainly there are.  With proper construction and installation techniques, these product s have proved to be adequate in many applications.  At Chateau Mill & Supply we see the advantages of plywood and have specialized in building a cabinet with stronger materials, better joinery, and then applying a good finish to both the exterior and interior of the cabinet.

MDF:

“Medium-density fiberboard (MDF or MDFB) is an engineered wood product formed by breaking down softwood into wood fibers, often in a defibrator, combining it with wax and a resin binder, and forming panels by applying high temperature and pressure. It is a building material similar in application to plywood but made up of separated fibers, not wood veneers. It is denser than normal particle board.” (Wikipedia)

 

MDF has been around since the 1980’s and has added another product to the pallet of available cabinet materials.  It is similar to particle board in some of its properties though it performs better in some categories.

Sheet good manufactures have begun to use MDF as the preferred core for hardwood plywood.  Because of the manufacturing techniques, it is very flat, and so veneers of hardwoods can be sliced thinner and still, after applying and sanding , yield an acceptable product.  This saves money for the sheet goods manufacture and so the MDF core products can be sold cheaper.   Because MDF is a high pressure composite, its skin is quite hard and can actually improve dent resistance of panels in comparison to their veneer core counterparts.  Structural integrity is somewhat compromised in comparison to plywood, and the product, like particle board is quite heavy.  It will deflect (bend or sag) under load so it is best suited to vertical applications.  Unsupported horizontal applications should be limited in span to reduce deflection especially in uses where heavy loads are anticipated.

 

Chateau Mill & Supply has chosen to include MDF as an acceptable alternative to plywood in instances when a veneer core plywood is not readily available. 

Alder veneers on an MDF Core

An example of a hybrid core - pine or fir are used for the center veneer core, MDF surrounds these, and the oak veneer is the exposed finish

Hybrid Cores:

Many sheet goods manufactures are also offering alternate plywood cores that include layers of either particle board or MDF.  Usually a material of this sort will have an central core of veneers incased by layers of particle board or MDF, and then covered on the exterior by the finish hardwood veneers.  This seems to be a compromise allowing the strength and structure of the veneers and the flat, hard surface to apply thin hardwood veneers to.  This reduces manufacturing and material costs and give the product the dent resistance preferred in the final application.  At Chateau Mill, we have also chosen to include these materials in our repertoire for their inherent strengths and in many cases because they are the only product available.