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Fire-retardant-treated products for exterior applications must be subjected to actual or accelerated weathering prior to fire testing. For fire-retardant-treated wood, the two accelerated weathering methods have been Method A and B of ASTM D 2898. The rain test is Method A of ASTM D 2898. Method B includes exposures to ultraviolet (UV) sunlamps in addition to water sprays. D 2898 was recently revised to include Methods C and D. Method C is the “amended rain test” described in the acceptance criteria for classified wood roof systems (AC107) of the ICC Evaluation Service, Inc. Method D is...

Climate index values for estimating decay hazard to wood exposed outdoors above ground (commonly known as Scheffer index values) were calculated for 280 locations in the United States (270 locations in the conterminous United States) using the most current climate normal data available from the National Climatic Data Center. These were data for the period 1971–2000. In general, the values appear to have been moderately higher during this period than the values listed by Scheffer. The values are listed, and a revised climate index map is provided.

Moisture control is a critical means of improving the performance of solid-color stain and paint on wood siding. In this article, recommendations are given for constructing a rain screen, sealing the end grain, and back-priming siding to achieve this goal. Rain screen con­struction and back priming inhibit water absorption and bleed from run-down extractives if water gets behind the siding. Inhibiting water absorption improves dimensional stability of siding, thus improving finish performance. Sealing the end grain with primer decreases paint peeling and bleeding of diffuse extractives...

Wood is a biological material, and its structure and organization are relicts of its biogenesis. From the hydrogen bonding of water molecules in the cell wall to extractives bleeding from knots in siding, the characteristics and behavior of wood are derived from its biological origin; this is my unashamedly biocentric view of wood structure. The structure of wood dictates that different material properties emerge and take primacy at different spatial and temporal scales, all determined by the tree that produced the wood and the ways the wood was processed. The appropriate wood structural,...

This paper summarizes recent laboratory and field data studies on thermal performance of stress-laminated timber highway bridges. Concerns about the reliability of stress-laminated deck bridges when exposed to sub-freezing temperatures triggered several investigations. Two laboratory studies were conducted to study the effects of wood species, preservative, moisture content, and temperature variations on pre-stressing bar forces (critical factor) in stress-laminated decks. The field performance of several stress-laminated timber bridges were monitored within a Nationwide Timber Bridge...

Because of the potential risk associated with moving firewood infested with emerald ash borer, the interstate movement of all hardwood firewood is currently restricted under Federal quarantine. Communities and firewood producers are now faced with decisions on how to treat firewood for interstate commerce. New regulations for heat sterilization of ash firewood require holding a core temperature of 160 °F for 75 min, much higher than the current international heating standard for treating solid wood packaging. The present study evaluated different heat-treatment options for various firewood...

In order to quantify the effect of temperature on the mechanical properties of pure nylon 6 and its composite with cellulose fibers (containing 25 wt% cellulose fibers), the materials were sampled and tested at three representative temperatures of 256, 296, and 336 K. Flexural and tensile tests were performed and the reductions in mechanical properties were evaluated. The highest reductions were observed in stiffness (modulus) values and the cellulose fibers remarkably enhanced the high temperature resistance of nylon. The reductions in mechanical properties were well explained by a simple...

A description of the occurrence and structure of “ray-intrusive” laticifers in the rays of species of Croton section Cyclostigma is provided. The systematic significance of laticifers within Croton section Cyclostigma is briefly discussed in relation to the section’s known production of red latex, commonly called “dragon’s blood”. A developmental hypothesis is offered and discussed in the context of the assumption that all laticifers in wood rays are non-articulated.

Interior gray enzymatic oxidative stain for white woods such as maple has plagued the wood industry for many years because methods that have been found to reduce stain are hard to scale up to industrial levels. We examined possible alternative treatments to eliminate stain in soft maple (Acer rubrum L.), and found that exposure to sulfur dioxide gas eliminates interior gray stain and that staining might occur at different temperatures depending on the age of the logs. Comparing sawn and split boards showed that both eliminated surface stain, but sawing eliminated it to a greater depth. A...

One method to determine past climate has been the use of leaf morphological characteristics of fossil leaves quantified using modern climate and canopy leaf characteristics. Fossil assemblages are composed of abscised leaves, and climate may be more accurately determined by using leaves from leaf litter instead of the canopy. To better understand whether taphonomic processes make a difference in this relationship, a north-central Florida woodland was sampled to determine the morphologically based climate estimates from these leaves. Leaves from woody, dicotyledonous plants were collected...