This Quality Review regular feature presents woodwork-related technical topics of common interest and importance to the design community, general contractors, and the architectural woodwork industry.
In recent history, the concealed material composition and construction details of interior architectural wood doors have certainly undergone a metamorphosis. Solid wood, once the only option for door construction, has in large measure given way to MDF, agrifiber, SLC, fire resistant composite, honey comb, and expandable paper core. However, when it comes to the visible face which any given transparently finished wood door exposes to the world, our impression of its aesthetics continues to be governed by the more immutable laws of human perception. Attributes such as color and light/dark values are obviously an important part of a door face’s overall appearance. But the main event is often the universe of grain and veneer characteristics which transparently finished wood doors offer. Doors specified to conform with the Architectural Woodwork Standards, Edition 2, 2014 (AWS2) are subject to the rules of Section 9, many of which establish minimum criteria for determining what constitutes acceptable AWI Premium or Custom Grade aesthetics for particular wood cutting methods and species. As the Standard states, these rules “shall govern, unless a project’s contract documents require otherwise.” The rules may also govern side-by-side with additional designer specifications which are not in conflict with the Standard.
One of the main devices used in Section 9 to organize these aesthetic criteria is the adoption of the “Hardwood Plywood and Veneer Association (HPVA) Door Skin Face Tables” (beginning on AWS page 258). Applying to flush, veneer covered doors, these tables quantify and set boundaries for the more common and discrete natural veneer characteristics. For example, allowable average numbers of pin knots within given door face area units are listed, and the allowable occurrence and size of mineral streaks are set. For Red and White Oak, the allowable degree of grain “slope and sweep” for Rift Cut veneer is described. All of the rules in these tables are measurable and apply to a total of fourteen predominant hardwood species used in Canadian and U.S. projects. The rules assume Plain Sliced, Quarter Cut, Rift Cut or Rotary Cut veneer. The AWS notes that those species not covered by the tables are governed by agreement between the designer and the door manufacturer regarding the allowable scope and properties of veneer characteristics.
Although the “Door Skin Face Tables” offer a wealth of information, they are not comprehensive in terms of door face aesthetics. Other considerations, such as the required match for Premium or Custom door pairs, or where veneer sequencing is required, appear the Section 9 “Material Rules”. Another significant source of information is the AWS Glossary (beginning on AWS page 490). It defines most of the terms used in the Door Skin Face Tables, but also provides the meaning of other terms bearing on wood grain aesthetics. “Figure”, an important example of this latter category, is defined as: “The natural pattern produced in the wood surface by annual growth rings, rays, knots, and natural deviations from the normal grain, such as interlocked and wavy grain, and irregular coloration.” Perhaps the most significant aspect of this definition is the acknowledgement that both “normal” and “deviant” grain is identifiable for wood or veneer of various species, cut, and grade. This implies a considerable degree of consensus. The aforementioned Door Skin Tables reflect such a consensus. So do other terms and definitions outside of those tables. For example, the AWS Glossary defines “normal” Rift Cut wood, as “achieved through the process of cutting at a slight angle…that produces a straight grain with minimal ray fleck.” The interruption of normal, straight Rift Cut grain by a deviant grain, such as interlocking or wavy grain, is the kind of thing a designer is trying to avoid when he or she specifies “No figure” in a door face.
Taking this example one step further, does the Standard comment regarding how much interlocking or wavy grain is acceptable before the perception of “normal” grain is obliterated? The AWS Glossary definition of “Slight” offers a guideline: If the trait in question “interferes with the overall aesthetic appearance of a panel [such as a door face]”, then that trait is not “slight”, and the appearance is nonconforming relative to a “no figure” specification.
The foregoing is a brief summary of the AWS rules and definitions a fabricator must juggle in order to provide consistently conforming door faces for any particular project. Designers may rely upon the Architectural Woodwork Standards to provide minimum quality criteria for any product and Quality Grade covered by that document. However, the discussion of “figure”, “normal vs. deviant” grain, and “slight” points out that detailed specifications can clarify a desired outcome and reinforce the Standard. This applies both to features a designer wishes to include and exclude from a product, and is especially true when dealing with product aspects that are complicated and potentially perceived differently from one person to another. Whether it’s decorative wall paneling or door faces, judgments regarding veneer characteristics and grain matching tend to fit that category.