Glossary
The following is provided as a primer. The discussion below should provide you with enough information to understand the terms that I use in the descriptions of items you may be contemplating for purchase.
See examples at right and also Pen Making Materials. A "burr" or burl is an abnormal growth, common to many trees, especially those that reproduce by "stooling". "Stooling" is the act of throwing out shoots from the tree stump, i.e. second growth. Burls tend to be more common in the genera Betula, Erica, Juglans, Quercus, Sequoia and Umus. A burl can be considered a benign growth on a tree. Although burls do not usually kill the host tree, it is obvious that some of the larger ones, which can exceed several tons, have consumed a large portion of the tree's resources. To be commercially usable, burls must be of fairly good size. Most stem burls occur as distinct projections from the trunk proper and range from a few inches in diameter to several tons. The Guiness Book of World Records reported about 30 years ago that a Sitka spruce produced a burl the size of a small house. One of the things that makes burls so interesting is their extremely disoriented wood tissues. There are two basic types of burls with respect to their internal structure. The first and less valuable of the two is referred to as the "onion" burl. This type consists of annual rings in highly contorted patterns that bulge out from the surface of the trunk. Quite often these layers are not adhered together well and the material falls apart when it is sawn into pieces as small as pen blanks. Some of the most highly figured, most intricate burls are of this type. The second type is pin or "eyed" burl. This is the more sought after and more valuable of the two. It is more highly organized in that it consists of a focal point, usually relatively small, from which "bud-like" growths fan out to the surface of the burl. When cut longitudinally, the buds appears as "straws". Cut across the "straws", at a right angle, they appear as "eyes". Some burls in cross section are literally solid eyes. Size of the eyes can vary considerably. (From 1/2 to 3/4 inches on maple to 1/8" on Black Ash). Other types of burl, such as California Buckeye or Thuya, grow strictly underground and are dug up by bulldozer. Some the size of small cars have been found. These require special care in curing and drying burl but can produce some truly spectacular and extremely beautiful patterns.
Colorwood
This product is quite similar to Dymondwood (below) except that the veneers are dyed hard maple, not impregnated and not compressed. Colorwood is offered in a range of primary and secondary colors as well as some bright pastels. Colorwood is not as hard as Dymondwood. This material is a natural for custom color pens for business and home use. See picture of pen blank in Pen Making Materials.
Dymondwood
This product is similar to Colorwood (above). Dymondwood is a brand name that technically falls into a class of manufactured woods called "compregs". Dymondwood is made from Baltic birch veneers which have been dyed various colors, impregnated with phenolic resins and laminated into a homogeneous mass under high temperature and pressure. This material is truly beautiful. See picture of pen blank in Pen Making Materials.
Figure
Figure broadly refers to the surface pattern of the wood. It results from the interactions of many features. They include the difference in density between early wood and late wood, the quantity of growth rings, the natural pigments and markings in the structure, the reaction to the tree to the effects of tension and compression, contortion around knots, swollen buts or limbs and the stunted growth of burls. These natural features, combined with the variety of grain types and the method of cut, produce the figure.
Grain
See examples at right. The word "grain" is often misapplied and misunderstood. Such terms as "coarse grained" or "fine grained" actually refer to the texture of the surface and not to the grain. The descriptions "end grain", "side grain" and "flat grain" are commonly used when referring to the way in which the wood is cut (transverse, parallel or radial). Grain actually refers to the way in which the natural wood fibers align with the main axis of the tree. Examples include: Straight ... fibers run parallel to main axis; Cross ... fibers no not run parallel to main axis; Interlocked .. grain spirals right and left; Spiral ... grain spirals in single direction; Wavy ... short undulating waves in regular sequence (fiddleback); Curly ... irregular undulations; Irregular ... as contortion and twisting around knots; Diagonal ...result of milling defects in normal straight grain.
Lustre
The ability of the wood cells to reflect light gives the surface lustre. Compact, smooth textured woods are more lustrous than their coarse textured counterparts. The ability of the wood to provide an excellent polish does not necessarily equate to its natural degree of lustre.
Plastics
There are many forms of plastic on the market that are suitable for use in pens. Historically, cellulose nitrate was used for high quality writing instruments in both Europe and the United States (as early as the 1920s). However, the material is quite flammable. In this country the cellulose materials are now sold in the form of cellulose acetate. Over the last couple years, the acrylics have gained a great deal of popularity because of their beauty. There are several "solid surface" materials that make excellent pens. Corian is 65% bauxite and 35% acrylic. AcryliGem and PolyGem are trade names for acrylics that have been especially formulated for the heat and fracture resistance required for making quality pens.
Spalted wood
See example of spalted oak pen at right. Spalting is the first stage of wood decay and is caused by several different forms of fungi. Spalting takes many forms and colors. The most desirable spalting features a spiderweb pattern of black lines which permeate the wood in random patterns. The density of the black lines is important in selecting spalted wood for pen making purposes. If a turned pen does not show a good amount and nice distribution of black lines, it does not make a good product. There are also cloud-like bursts that occur in several different colors (however, they are usually not as attractive as the spiderweb effect). If spalting has not progressed too far, the wood may be turned without stabilizers.
Stabilized Wood
Potentially beautiful materials that are not good turning materials can be hardened through the introduction of a special blend of monomers and acrylics. Soft or brittle woods such as spalted woods and burls are prime candidates for this procedure. Dyes can be mixed with the stabilization chemicals to produce unusual and attractive results. The resulting material is resistant to temperature changes, humidity extremes, UV light, salt water and most acids and solvents. Since the stabilization process is expensive and labor intensive only the most select raw materials are generally uses. Stabilized materials take on high finish and are most attractive.
Texture
The texture or "feel" of the wood surface is the result of the difference between the dimensions of the pores and the width and quantity of the rays. Timbers which have wide vessels and broad rays are coarse textured and those with narrow vessels and thin rays are fine textured. When the difference in late and early wood zones is great, the texture is said to be uneven and when there is little difference it is said to be even textured.