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Air Drying vs Kiln Drying Regarding Exterior Joinery | ||||||||||||||||||||||||||||||
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Chromosomes Really Matter | ||||||||||||||||||||||||||||||
Redwood: Grown exclusively along a 200-mile stretch of northern California coastline. Because this industry is so tightly regulated, the former logging giants of Humboldt and Mendocino counties are littered with abandoned mills. It is currently being harvested on a short cycle, producing sustainable results that are, unfortunately, without the properties inherent in old growth harvests. Redwood has a high concentration of tannins, like teak and western cedar, that thwart the propagation of bacteria (rot). These tannins require a growth cycle to mature into their full genetic strength and are consequently absent in the present-day redwood harvests. Due to the abnormally large diameter of the trunk, the 'heart grain', located near the center, and oldest part of the tree, is tight and stable. But 'old growth' redwood is available only as a special "Forest Floor" permit or as a recycled product, drawn largely from a series of former military bases in California that were built with old growth redwood and were all closed in the 90's. The current 'short-cycle' redwood has a fibrosity in its grain that is far far more porous than old growth, and therefore, far less stable or visually pleasing.
**Retail Cost: Approximately $7/per board ft. for kiln-dried clear all-heart. (In northern California. Far far more elsewhere)
*NOTE: We interrupt here because it is worth noting that the tannin oils mentioned above as the identifiable properties of both Teak and Redwood are also the potential menace. Glue, as in the woodworker's glue, must have a porous surface to grip or adhere to. Because these tannin oils emanate from the tree's fiber to coat the surface, any glue applied will simply sit on the skin and fail to create the sort of bond required. Almost immediately after both redwood and teak are milled or a joint is cut, the oils begin rising to the surface to prevent a glue-bond. The answer? Assuming one mills all their components and then turns to gluing and assembling, the technique involves a light hand-sanding off the new thin layer of oils that have risen since the milling, and then without delay, apply the glue and clamp the joint air-tight, all before the oils rise to coat the face of even the most freshly milled surface. Mahogany: There are many species of mahogany--usually denoted by the country of origin, but not always. Santos, Sapele, African, Fiddle-back, Philippine, Honduras, and Cuban. They are all exotic and endangered and yet with proper research, available as sustainable with the exception of Cuban. The mahogany industry has been over harvested. If a sustainable source can be found, look for full figuring and a deep reddish brown coloring. Mahogany, although a good species for resisting the elements, does not posses the same ideal characteristics as teak, cedar, and redwood. It will shows signs of wear if not maintained.
CEDARS Port Orford: Grown and harvested and milled in small, select locations in the Pacific Northwest. Fully matured harvests can be difficult or even impossible to find. A creamy white hue, aging to a stately silvery gray. Smooth with no raised grain. Due to the pale nature of its coloring, it gives unlimited options when staining. (Redwood, teak, western cedar, and mahogany are dark and cannot take lighter stain pigments) A unique, strong ginger-like scent, due to the volatile tannin oils. Denser than other cedars. Dimensionally unstable, which means that because of the early harvests, there is far more fiber between the growth rings, giving way to a vulnerability for checking and cracking as it dries. Excellent resistance to insect and fungi infestation. Although in some areas, the lower grade of Port Orford is available as a green, knotty product sold as decking, the clear, double-kiln-dried grade remains largely unavailable to the retail public. This is the wood Charles and others used in the 1970's in San Francisco---until it was all gone. A grove was planted in 1978, and although they are harvesting, as mentioned above, it is a premature harvest falling far short of the old-growth properties.
Why doesn't Prowell provide fence and gate posts? 1) A common means of circumventing the expense of teak or affordable access to redwood and cedar to those in the east is the process of treating more affordable woods such as Douglas Fir with a chemical that resist or thwarts bacteria infestation. For the longest time, this was best accomplished with a thick coating of creosote, which might be most recognizable in connection with the railroad ties. When creosote was outlawed in the mid-1980's, the method of pressure treating was adopted. Injected by a series of punctures pressured by a vacuum press to a depth of about 1/4" from the surface, an arsenic-based tonic allowed the use of fir and pine and all sorts of affordable species to be used in the construction of decks and fence posts and anything deemed susceptible to rot.
Still commonly used today as a cost saving measure, a number of problems are worth noting.
1) Pressure-treated preservatives do in fact transfer to the touch, as well as drain down into the water table. California recently, finally, prohibited such products from all publicly accessed areas. ![]() 2) When cut, the fiber is exposed where the arsenic has not penetrated, thus requiring the direct application of a medley of products to coat the raw grain. These are far far more transferable than the pressure-treating process, and a good deal more toxic. 3) The cost savings of pressure-treating may allow one to actually afford a deck, but entertaining on that deck, above the wafting odors of poison that permeate the structural underlay, will make for a far greater problem over time. And yet it is not uncommon for those sites east of the Mississippi to opt for this solution. We are not stewards of the earth. We are woodworkers, and will not preach a high-minded sermon to those who prefer pressure-treated posts. Requests: PROPERTES WESTERN CEDAR
Thank you, and I hope the above material has been informative and helpful and perhaps somewhat enlightening.
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