Preservatives against decay

McCarthy and coworkers (74) at the Australian Forest Products Laboratory reported that a pressure treatment for pine posts with zinc-copper-chromium-arsenic-phosphorus preservative produced a leach-resistant treatment having both fire retardancy and preservation against decay. This treatment system is reported to have commercial application in Australia. 

Wood is painted in order to preserve from decay, to minimize changes in moisture content that lead to distortion, and for decoration. It is a waste of time and effort to apply expensive paints or stains to exterior wood not previously treated with preservative. Preservatives are designed to penetrate the timber to protect against microorganisms and insect attack. Modern preservatives can be over-coated with paint without problems. 

Marine borers present a severe challenge. Some preservatives that are very effective against decay fungi and insects do not provide protection in seawater.Thus, despite severe reservations about the continued use of creosote and CCA these remain the only viable treatments currently available. Creosote is most commonly used, preventing attack by all marine borers except Limnoria tripunctata. 

Preservative Spoilage deterrent. A chemical compound that is added to protect against decay or decomposition. 

WOLMAN Treat OO wood preservative shall be used only for field treatment of previously WOLMANIZED pressure treated lumber, piling or plywood to help protect against decay causing fungi and termite attack. It conforms to AWPA Standard M-4. 

The best protection for wood against the attack of decay fungi, insects, or marine borers is obtained by applying preservatives under pressure before installation (61,62). Both oil-type preservatives, such as creosote or petroleum solutions of pentachlorophenol, and waterborne preservatives, such as copper-chrome arsenate and ammoniacal-copper arsenate, are used when wood is to be in direct contact with the ground or in the marine environments. 

Preservatives (LD, DW, ADW, HC, FC) Guards against product aging by decay, discoloration, oxidation, and bacterial attack Ability to decrease water availability Butylated hydroxytoluene Ethylene diamine Glutaraldehyde 0.05-0.2% 0.05-0.2%... 

Takahashi, M., Imamura, Y. and Tanahashi, M. (1989). Effect of acetylation on decay resistance of wood against brown rot, white rot and soft rot fungi. International Research Group on Wood Preservation, Doc. No. IRGAVP 3540. 

Businesses engaged in treating wood to prevent decay and to protect against insects and fire are included in this group. Poles, piles, and foundation plates are typical products requiring wood preserving. 

All of the commercial wood preservatives presently used in the United States are effective in preventing attack by microorganisms because of their toxic nature. Most of these preservatives are classified as broad spectrum preservatives, that is, effective against several different types of living systems. Because of the toxic hazards and environmental concerns and because prevention of wood decay is needed if we are to extend our timber resources by increasing its service life, we have investigated alternative methods of wood preservation not based on toxicity for their effectiveness. 

Mother earth never attempts to farm without live stock, she always raises mixed crops great pains are taken to preserve the soil and to prevent erosion the mixed vegetable and animal wastes are converted into humus there is no waste the processes of growth and the processes of decay balance one another ample provision is made to maintain large reserves of fertility the greatest care is taken to store the rainfall both plants and animals are left to protect themselves against disease. 

Preservatives. Although not classified generally as wood finishes, preservatives in wood do protect against weathering and decay, and a great quantity of preservative-treated wood is exposed without any additional finish (2). There are three main types of preservative ... 

It is thermally stable up to 170 C and has solubility in water of about 33 ppm. Its primary promotion has been in the wood preservation industry as it is effective against a range of wood decay organisms. Its use in the plastics industry is only so far promotional. It is a white to yellow solid that is both metal and halogen free (Figure 40). 

Borates (such as boric acid, borax, disodium octaborate tetrahydrate) have been used as broad-spectrum wood preservatives for over 50 years. Zinc borate has a shorter history as wood preservative, but it is well accepted in that capacity. There is a belief that, generally, zinc borate is more effective against fungal decay compared to mold inhibition, though systematic studies, using different composite materials, are apparently lacking. 

However, natural-based materials like starches and soybean oils are used in direct competition to animal or human food consumption. Technically, they are not at all suitable for high modulus adhesive and sealant joints. They usually are sensitive to hydrolysis and oxidization. Exposure to atmospherie eonditions or chemical attack can drastically limit their service life expectancy. They are sensitive to elevated temperatures and need to be protected against microbiological decay with more or less toxic preservatives. In light of those features and based on today s knowledge some important conclusions can be drawn ... 

---