Little is known about the bacteria that degrade cellulose. Symbiotic bacteria in Xylophaga may play a role in the degradation of sunken wood. Alphaproteobacteria, Flavobacteria, Actinomycetota, Clostridia, and Bacteroidota have been detected in wood submerged for over a year. [49] See also

For example, if the moisture content of the delivered wood is 12% and the optimal MC is 6%, then physical problems will occur during the acclimation process.

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Six tropical hardwoods, selected to emphasize the range of natural variation in colour and figure: (A) Indian rosewood, (B) lignum vitae, (C) zebrawood, (D) padauk, (E) tulipwood, and (F) teak. (more) To avoid this problem, wood flooring should never be stored where environmental conditions are uncontrolled, such as garages and exterior patios. Therefore, just because the wood is kiln-dried doesn’t mean it has lost the ability to absorb moisture. It will continue to absorb and release moisture until it comes into balance with the surrounding air. What are Acceptable Moisture Levels in Wood?

Aliphatic compounds include fatty acids, fatty alcohols and their esters with glycerol, fatty alcohols (waxes) and sterols (steryl esters). Hydrocarbons, such as alkanes, are also present in the wood. Suberin is a polyester, made of suberin acids and glycerol, mainly found in barks. Fats serve as a source of energy for the wood cells. [34] The most common wood sterol is sitosterol, and less commonly sitostanol, citrostadienol, campesterol or cholesterol. [33] Oven dry testing is the oldest method for measuring the moisture content of wood. The process is time-consuming but produces accurate results if followed correctly. Here’s how it works…Wood is also commonly used as shuttering material to form the mold into which concrete is poured during reinforced concrete construction. For solid strip flooring (less than 3” wide) there should be no more than a 4% difference in moisture content between properly acclimated wood flooring and subflooring materials. N.B. fossils show origins of wood". CBC.ca. August 12, 2011. Archived from the original on August 13, 2011 . Retrieved August 12, 2011. In fact, according to M. Steven Doggett, Ph.D. LEED AP, the founder of Built Environments, Inc., wood moisture content as high as 15% can cause corrosion of metal fasteners and at 16% may lead to fungal growth.

The single most revealing property of wood as an indicator of wood quality is specific gravity (Timell 1986), [23] as both pulp yield and lumber strength are determined by it. Specific gravity is the ratio of the mass of a substance to the mass of an equal volume of water; density is the ratio of a mass of a quantity of a substance to the volume of that quantity and is expressed in mass per unit substance, e.g., grams per milliliter (g/cm 3 or g/ml). The terms are essentially equivalent as long as the metric system is used. Upon drying, wood shrinks and its density increases. Minimum values are associated with green (water-saturated) wood and are referred to as basic specific gravity (Timell 1986). [23] Anywhere from 1.5 – 2 gallons were gone from it. I’m not sure whether it was a slow or fast leak, but I’m guessing slow-ish as the area of wood that was soaked wasn’t larger than the container. For instance, Seattle’s EMC ranges from 12.2% to 16.5%. In the Midwest, the EMC of wood or lumber in Des Moines, Iowa, ranges from 12.4% to 14.9%. The main terpenes occurring in the softwood include mono-, sesqui- and diterpenes. [34] Meanwhile, the terpene composition of the hardwood is considerably different, consisting of triterpenoids, polyprenols and other higher terpenes. Examples of mono-, di- and sesquiterpenes are α- and β-pinenes, 3-carene, β-myrcene, limonene, thujaplicins, α- and β- phellandrenes, α-muurolene, δ-cadinene, α- and δ-cadinols, α- and β- cedrenes, juniperol, longifolene, cis-abienol, borneol, pinifolic acid, nootkatin, chanootin, phytol, geranyl-linalool, β-epimanool, manoyloxide, pimaral and pimarol. Resin acids are usually tricyclic terpenoids, examples of which are pimaric acid, sandaracopimaric acid, isopimaric acid, abietic acid, levopimaric acid, palustric acid, neoabietic acid and dehydroabietic acid. Bicyclic resin acids are also found, such as lambertianic acid, communic acid, mercusic acid and secodehydroabietic acid. Cycloartenol, betulin and squalene are triterpenoids purified from hardwood. Examples of wood polyterpenes are rubber ( cis-polypren), gutta percha ( trans-polypren), gutta-balatá ( trans-polypren) and betulaprenols ( acyclic polyterpenoids). [33] [34] The mono- and sesquiterpenes of the softwood are responsible for the typical smell of pine forest. [33] Many monoterpenoids, such as β-myrcene, are used in the preparation of flavors and fragrances. [34] Tropolones, such as hinokitiol and other thujaplicins, are present in decay-resistant trees and display fungicidal and insecticidal properties. Tropolones strongly bind metal ions and can cause digester corrosion in the process kraft pulping. Owing to their metal-binding and ionophoric properties, especially thujaplicins are used in physiology experiments. [40] Different other in-vitro biological activities of thujaplicins have been studied, such as insecticidal, anti-browning, anti-viral, anti-bacterial, anti-fungal, anti-proliferative and anti-oxidant. [41] [42] Most extractives can be categorized into three groups: aliphatic compounds, terpenes and phenolic compounds. [33] The latter are more water-soluble and usually are absent in the resin.

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Aside from water, wood has three main components. Cellulose, a crystalline polymer derived from glucose, constitutes about 41–43%. Next in abundance is hemicellulose, which is around 20% in deciduous trees but near 30% in conifers. It is mainly five-carbon sugars that are linked in an irregular manner, in contrast to the cellulose. Lignin is the third component at around 27% in coniferous wood vs. 23% in deciduous trees. Lignin confers the hydrophobic properties reflecting the fact that it is based on aromatic rings. These three components are interwoven, and direct covalent linkages exist between the lignin and the hemicellulose. A major focus of the paper industry is the separation of the lignin from the cellulose, from which paper is made. Record, Samuel James (1914). The Mechanical Properties of Wood, Including a Discussion of the Factors Affecting the Mechanical Properties, and Methods of Timber Testing. J. Wiley & sons, Incorporated. In grading lumber and structural timber, knots are classified according to their form, size, soundness, and the firmness with which they are held in place. This firmness is affected by, among other factors, the length of time for which the branch was dead while the attaching stem continued to grow.