All steps taken to ensure long wood life are under the definition of wood conservation (wood processing).
Apart from structural wood preservation measures, there are a number of different preservatives and processes (chemicals) (also known as wood processing , wood processing or pressure treatment ) that can extend the life of wood, wood, wooden or engineered wood structures. This generally increases resistance and resistance from being destroyed by insects or fungi.
Video Wood preservation
Histori
As Richardson puts it, wood care has been practiced almost during the use of the wood itself. There is a record of preservation of timber that reached back to ancient Greece during the reign of Alexander the Great, in which wooden bridges were immersed in olive oil. The Romans protected their hull by brushing wood with tar. During the wood preservation the Industrial Revolution became the cornerstone of the wood processing industry. Inventors and scientists such as Bethell, Boucherie, Burnett and Kyan made historic developments in wood preservation, with solutions and preservative processes. Commercial pressure treatment began in the second half of the 19th century with the protection of cross-rail relationships using creosote. The treated wood is mainly used for industrial, agricultural, and utility applications, where it is still in use, until its use grew rapidly (at least in the United States) in the 1970s when homeowners began building decks and backyard projects. Innovation in processed wood products continues to this day, with consumers becoming more interested in less toxic materials.
Maps Wood preservation
Dangers
Woods that have been pressurized by industry with approved preservatives pose a limited risk to the public, and must be disposed of properly. As of December 31, 2003, the US timber treatment industry ceased maintenance of residential timber with arsenic and chromium (chromed copper arsenate, or CCA). This is a voluntary agreement with the United States Environmental Protection Agency. The CCA is replaced by copper-based pesticides, with the exception of certain industrial uses. CCAs may still be used for outdoor products such as trailer beds and non-residential construction such as piers, piers, and agricultural buildings. Industrial wood preservation chemicals are generally not available directly to the public and may require special approval to import or purchase depending on the products and jurisdictions where used. In most countries, industrial timber preservation operations are verifiable industrial activities that require licenses from relevant regulatory authorities such as EPA or equivalent. Reporting and licensing conditions vary greatly depending on the particular chemical used and the user's country.
Although pesticides are used to treat wood, keeping timber protects natural resources (in the short term) by allowing wood products to last longer. The previous poor practices in industry have left a contaminated soil and water heritage around wood treatment sites in some cases. However, under current industry practice and regulatory control as applied in Europe, North America, Australia, New Zealand, Japan and elsewhere, the environmental impact of this operation should be minimal.
Wood treated with modern preservatives is generally safe to handle with appropriate handling and personal protective measures. However, treated timber may pose particular hazards in some circumstances such as during combustion or where loose particles of wood dust or other toxic residues are produced or if treated wood is in direct contact with food and agriculture.
Preservative containing copper in the form of microscopic particles has recently been introduced to the market, usually under the trademark "micron" or "micro" and mentions such as MCQ or MCA. The manufacturer states that this product is safe and EPA has registered this product.
The American Wood Protection Association (AWPA) recommends that all processed wood is accompanied by a Consumer Information Sheet (CIS), to deliver safe handling and disposal instructions and potential health and environmental hazards of treated wood. Many manufacturers choose to provide Material Safety Data Sheets (MSDS) instead. Although the practice of distributing MSDS over CIS is widespread there is an ongoing debate over practices and how best to communicate potential hazards and mitigate hazards to end users. Both the newly adopted MSDS or SDS are required for timber treated under current US Federal law.
Business and organizations
America
American Wood Protection Association
[4]
Established in 1904, the American Wood Protection Association (AWPA), formerly the Wood-Preservers' Association, is a nonprofit organization that is the standard setting body for wood preservation standards (including ANSI). The AWPA standard is developed by its technical committee in an open consensus process involving individuals from all aspects of preservation of wood: Preservative producers and preservative components; producers of processed and unprocessed wood products; end user of processed wood; engineers, architects, and building code officials; government entities, academics, and other groups with a common interest in timber conservation. The AWPA standard is universally defined for timber conservation in the US, and is recognized worldwide.
The AWPA standard helps ensure that processed wood products function satisfactorily for their intended use. They are recognized and used by most, if not all, wood processed specifiers including electric utilities, marine, road and building construction as well as by local, state, and federal governments. "AWPA", "American Wood Protection Association", AWPA Standard identifier (e.g., U1, T1, M4, etc.), and the use of Category titles (eg UC1, UC3B, UC4A, etc.) are trademarks of AWPA and intellectual property AWPA and its Technical Committee.
Wood preservative systems manufactured under the AWPA standard system for the housing market should be checked under the strict American Lumber Standards Committee (ALSC) third party inspection system to ensure compliance with AWPA standards.
While many wood preservative systems are manufactured under the AWPA standard system, there are preservative wood products on the market that have not received AWPA standard status and are not subject to the ALSC inspection system. Compliance with AWPA and ASLC will be recorded by the AWPA logo in the final product tag.
Marketing of wood preservatives
In general, marketers of timber preservation systems prefer a particular terminology. For example, the term 'preservative' is used in preferences for words such as: chemistry, pesticides, fungicides or biocides. And with newer preservatives, the term 'micronized' is preferred over nanoparticles or nanotechnology, which can raise public safety concerns.
Chemical preservatives
Chemical preservatives can be classified into three broad categories: water-borne preservatives, preserved preservatives with oil, and mild organic solvent preservatives (LOSPs). These are discussed in more detail below.
Micronized copper technology
Micronised or dispersed technology was recently introduced in the US and Europe. In this system, copper is ground for microscopic particles and suspended in water rather than dissolved in chemical reactions as well as other copper products such as ACQ and Copper Azole. There are currently two particulate copper systems in production. One system uses a quat biocide system (known as MCQ) and is a take-off from ACQ. The other uses azole biocide (known as MCA or? CA-C) and is the take-off of Copper Azole.
Supporters of particulate copper systems make the case that particulate copper systems work well or better than dissolved copper systems as wood preservatives, but other industry researchers disagree. None of the particulate copper systems have been submitted to the American Wood Protection Association (AWPA) for evaluation, so particulate systems should not be used in applications where AWPA standards are required. However, all particulate copper systems have been tested and approved to establish code requirements by the International Code Council (ICC). Particulate copper systems provide lighter shades than dissolved copper systems such as ACQ or copper azole.
Supporters of copper microsystems claim that this system is subject to third-party checks under a quality monitor program. However, the monitoring program is not subject to supervision by the American Lumber Standards Committee (ALSC) as required for the AWPA standard system.
Two particulate copper systems, one marketed as MicroPro and the other as Wolmanized using CA-C formulations, have achieved Product Eco-Friendly certification (EPP). The EPP certification is issued by Scientific Certifications Systems (SCS), and is based on comparative life cycle impact assessment with industry standards.
The size of the copper particles used in micronized copper beads ranges from 1 to 700 nm with an average of below 300 m. The larger particles (such as micron-scale particles actually) of copper simply do not penetrate the wooden cell wall. These micronized preservatives use copper oxide nanoparticles or copper carbonate, which there are allegations of security issues. An environmental group recently petitioned the EPA to revoke the registration of copper products that are monopolized on security issues.
Alkalin copper quaternary
Alkaline copper quaternary (ACQ) is a preservative made of copper, fungicide, and quaternary ammonium compounds such as didecyl dimethyl ammonium chloride, an insecticide which also adds to the treatment of fungicides. ACQ has been widely used in the US, Europe, Japan and Australia following CCA restrictions. Its use is governed by national and international standards, which determines the volume of preservative use required for a particular end-use of wood.
Because it contains high levels of copper, ACQ-treated wood is five times more corrosive to ordinary steel. It is necessary to use fasteners to meet or exceed the requirements for ASTM A 153 Class D, such as ceramic coated, as it is only galvanized and even the general level of stainless steel corrosion. The US began mandating the use of wood preservatives that did not contain arsenic for most of the wood used in the settlements in 2004.
The American Wood Protection Association (AWPA) standard for ACQ requires 0.15 lb/ft 3 (PCF) retention for above ground use and 0.40 lb/leg 3 for ground contact.
Chemical Specialization, Inc. (CSI, now Viance) received the Presidential Green Presidency of the US Presidential Presidency in 2002 for the commercial introduction of ACQ. Its widespread use has removed large amounts of arsenic and chromium previously present in the CCA.
Copper azole
Preservative Azole copper (denoted as CA-B and CA-C under the American Wood Protection Association/AWPA standards) is a major copper-based wood preservative that has been widely used in Canada, USA, Europe, Japan and Australia after CCA restrictions. Its use is governed by national and international standards, which determines the volume of preservative use required for a particular end-use of wood.
An azole copper similar to ACQ with the difference is that soluble copper preservatives coupled with azole co-biocide such as organic triazoles such as tebukonazole or propiconazole, are also used to protect food crops, not quat biocides used in ACQ. Azole co-biocide produces azole copper products that are effective at low retention rather than those required for equivalent ACQ performance. The general appearance of wood treated with copper azole preservatives is similar to CCA with green staining.
The processed azole wood copper is marketed widely under the Preserve CA and Wolmanized brands in North America, and the Tanalith brand throughout Europe and the international market others.
AWPA standard retention for CA-B is 0.10 lb/leg 3 for above ground applications and 0.21 lb/feet 3 for soil contact applications. Azole copper Type C, denoted as CA-C, has been introduced under the Wolmanized and Preserve brand. AWPA standard retention for CA-C is 0.06 lb/ft 3 for above ground applications and 0.15 lb/feet 3 for soil contact applications.
Naphthenate copper
Copper naphthenate, found in Denmark in 1911, has been used effectively for many applications including: fencing, canvas, nets, greenhouses, power lines, rail connections, honeycomb, and wooden structures in contact with the soil. Naphthenate copper is registered with EPA as an unrestricted use pesticide, so there is no federal applicator license requirement for its use as a wood preservative. Copper Naftenate can be applied with a brush, dye, or pressure treatment.
The University of Hawaii has found that naphthenate copper in wood at loading of 1.5 lbs per cubic foot is resistant to Formosa termite attack. On February 19, 1981, the Federal Register outlined the EPA's position on health risks associated with various wood preservatives. As a result, the National Park Service recommends the use of copper naphthenate at its facility as an approved substitute for pentachlorophenol, creosote, and inorganic arsenical. A 50-year study presented to AWPA in 2005 by Mike Freeman and Douglas Crawford says, "This study reviews the condition of the treated wood posts in southern Mississippi, and statistically calculates the new post-life lifespan." It is stipulated that commercial wood preservatives, such as pentachlorophenol in oil, creosote, and naphthenate copper in oil, provides excellent protection for posts, with life span now calculated over 60. Strangely, creosote and penta are treated post at 75% of recommended AWPA retention, and naphthenate copper at 50 % of the required AWPA retention, delivering excellent performance on the AWPA Hazard Zone site 5. This untreated southern pine stuck for 2 years on this test site. "
AWPA M4 Standard for preservative care of preserved wood products, reads, "The feasibility of a preservation system for field processing should be determined by the type of preservative originally used to protect the product and the availability of field processing preservatives.Because many preserved products are not packaged and labeled for use by the general public, a different system of genuine maintenance may need to be used for site maintenance Users should read and follow the instructions and precautions listed on product labels when using these materials Preservatives of copper naphthenate contain at least the recommended 2.0% copper metal for materials originally treated with copper naphthenate, pentachlorophenol, creosote, creosote solution or waterborne preservatives Standard M4 has been adopted by the International Code Code (IBC) section International Code Code (ICC) 2015 2303.1.9 Defended Wood, and 2015 International Re sidential Code (IRC) R317.1.1 Field of Care. The American State Highway and Transportation Association of AASHTO has also adopted the AWPA M4 Standards.
Water-borne copper naphthenate is sold to consumers under the trade name QNAP 5W. Napthenates copper containing 1% copper oil as a metal solution sold to consumers under Copper Green, and Wolmanized Copper Coat, 2% copper as a metal solution sold under the Tenino trade name.
chrome copper arsenate (CCA)
In CCA treatment, copper is the main fungicide, arsenic is a secondary fungicide and insecticide, and chromium is a fixative that also provides ultraviolet (UV) light resistance. Recognized for the greenish color implanted into wood, the CCA is a very common preservative for decades.
In the pressure treatment process, the aqueous CCA solution is applied using a vacuum and pressure cycle, and the treated wood is then stacked to dryness. During the process, the oxide mixture reacts to form an insoluble compound, helping to overcome the problem of washing.
This process can apply a variety of preservatives at different levels of pressure to protect wood against increased attack rates. Enhance protection can be applied (in increasing order of attacks and treatment) to: atmospheric exposure, implantation in soil, or insertion into the marine environment.
In the last decade, concern has been raised that chemicals can seep from wood to surrounding soil, resulting in higher concentrations than the naturally occurring background. A study cited in the Journal of Forest Products found 12-13% of the nutritious copper arsenate washed from compost-treated wood over a 12-month period. Once these chemicals have been peeled off the wood, they tend to bind the soil particles, especially in soil with clay or soil more alkaline than neutral. In the United States the US Consumer Product Safety Commission issued a report in 2002 stating that arsenic exposure from direct human contact with CCA-treated wood may be higher than previously thought. On January 1, 2004, the Environmental Protection Agency (EPA) in a voluntary agreement with industry began to restrict the use of CCAs in processed timber in residential and commercial construction, with the exception of vibration and shingles, permanent wood foundations, and certain commercial applications. This is an attempt to reduce arsenic use and improve environmental safety, although the EPA is careful to show that they have not concluded that the CCA treating wooden structures in services poses unacceptable risks to society. The EPA does not call for the removal or dismantling of existing CCA handling timber structures.
In Australia, Australian Pesticides and Veterinary Drug Authorities (APVMA) restrict the use of CCA preservatives for timber treatment used in certain applications from March 2006. CCAs may no longer be used to treat timber used in 'intimate human contact' applications such as equipment children's playground, furniture, housing decking and handrailing. Use for residential, commercial and industrial applications with low contacts remains unrestricted, as is its use in all other situations. APVMA's decision to limit the use of CCAs in Australia is a precaution, although the report found no evidence to suggest that CCA-treated wood poses unreasonable risks to humans in normal use. Similar to the US EPA, APVMA does not recommend the dismantling or removal of existing CCA-treated wooden structures.
In Europe, Directive 2003/2/EC limits the marketing and use of arsenic, including CCA wood care. CCA treated wood is not permitted for use in residential or domestic construction. It is permitted for use in a variety of industrial and public works, such as bridges, highway safety fences, power transmission and telecommunication poles. In the UK, wood waste treated with CCAs is classified in July 2012 as hazardous waste by the Department of Environment, Food and Rural Affairs.
Other copper compounds
These include HDO copper (Bis- (N-cyclohexyldiazeniumdioxy) -copper or CuHDO), copper chromate, copper citrate, acid copper chromate, and ammoniacal copper arsenic zinc (ACZA). The treatment of CuHDO is an alternative to CCA, ACQ and CA used in Europe and in the approval stage for the United States and Canada. ACZA is commonly used for marine applications.
Borat preservatives
Boric, oxide and salt (borate) acids are effective wood preservatives supplied by various brand names worldwide. One of the most commonly used compounds is disodium octaborate tetrahydrate (commonly abbreviated as DOT). Borasikan processed wood has a low toxicity in humans, and does not contain copper or other heavy metals. However, unlike most other preservatives, the borate compound does not become fixed in the wood and can partially fade if exposed repeatedly to water flowing away rather than evaporation (evaporation leaves the borate behind so it does not matter). Although leaching usually will not reduce the concentration of boron below the effective level to prevent mold growth, borate should not be used where they will be exposed to repeated rain, water or soil contact unless the exposed surface is treated to reject the water. Zinc borate compounds are less suspicious of leaching than sodium-borate compounds, but are still not recommended for underground use unless the wood is first sealed. Recent interest in low-toxic wood for residential use, along with new regulations limiting some timber preservation agents, has led to a revival of the use of borate-treated wood for flooring and internal structural members. Researchers at CSIRO in Australia have developed organoborates that are much more resistant to washing, while still providing wood with good protection against termites and fungi. The cost of modified borate production will limit their widespread retrieval but will likely be suitable for certain niche applications, especially where low mammalian toxicity is very important.
PTI preservative
Recent concerns about the health and environmental impacts of metal wood preservatives have created market interest in non-metallic wood preservatives such as Propiconazole-Tebuconazole-Imidacloprid better known as PTI. The Standards of the American Wood Protection Association (AWPA) for PTI require retention of 0.018 lb/ft3 (PCF) for above ground use and 0.013 lb/ft3 when applied in combination with wax stabilizers. The AWPA has not yet developed standards for PTI soil contact preservatives, so PTI is currently limited to above ground applications such as decks. All three PTI components are also used in food crop applications. The very low retention required for PTI-suppressed timber further limits the impact plus substantially lowers the transporting cost and associated environmental impacts for shipping preservation components to the pressure of treating crops.
PTI preservatives provide little color to the wood. Manufacturers generally add a dye or a small amount of copper solution to identify the wood as a treated pressure and better match the color of other treated wood products with other pressures. PTI wood products are very well adapted for paint and coloring applications with no bleed-through. The addition of wax stabilizers allows lower preservation of the preserves plus substantially reduces the tendency of the wood to curl and split as it dries. In combination with the maintenance app and the normal deck sealer, the stabilizer helps maintain performance and performance over time. PTI pressure treated wood products are no more corrosive than untreated and approved for all types of metal contacts, including aluminum.
Pressure PTI treated wood products are relatively new to the market and not widely available in stores supply of buildings. However, there are some suppliers who sell PTI products for shipping anywhere in the US on the basis of work lot orders.
Sodium silicate-based preservatives
Sodium silicate is produced by combining sodium carbonate with sand or heating both materials under pressure. It has been used since the 19th century. This can be a barrier against insect attacks and has a small fire resistance; However, it is easily washed out of wood by moisture, forming layers like debris on wood.
Timber Treatment Technology, LLC, markets TimberSILÃ,®, wood sodium silicate preservatives. TimberSILÃ,® ownership process surrounds wood fibers with a protective and non-toxic amorphous glass matrix. The result is a product called "Glass Wood," a material that is flame retardant, moisture-proof, decaying, and decay-proof, and superior in strength to unprocessed wood. Another option is to use plywood, fireproof plywood
Potassium silicate-based preservatives
There are a number of European natural paint makers who have developed potassium waterglass preservatives. They often include boron compounds, cellulose, lignin and other plant extracts. They are surface applications with minimal impregnation for internal use.
Bifenthrin spray preservative
In Australia, water-based bifenthrin preservatives have been developed to improve the resilience of wood insects. Because the preservative is applied with a spray, it only penetrates 2 mm outside the cross section of wood. Concern has been raised about whether this thin envelope system will provide insect protection in the long term, especially when exposed to sunlight for a long time.
Flame retarded
The processed wood uses refractory chemicals that remain stable in high-temperature environments. Fireproofing is applied under pressure on wood treating plants such as preservatives described above, or used as surface coating.
In both cases, treatment provides a physical barrier against the spread of fire. The wood chars are treated but do not oxidize. This effectively creates a convective layer that transfers the heat of fire to the wood in a uniform way which significantly slows the progress of fire into the material. There are several commercially available wood based construction materials using pressure treatments (such as those marketed in the United States and elsewhere under the tradenames "FirePro", "Burnblock" 'Woodsafe, Dricon', 'D-Blaze,' and 'Pyro -Guard '), as well as factory-applied coatings under the trade names' PinkWood' and 'NexGen'. Multiple on-site coatings as well as brominated flame retardants have lost support due to security concerns as well as concerns regarding application consistency. Special care is also available for wood used in weather-exposed applications.
The only flame retardant applied to commercially available impregnation in Australia is 'NexGen'. The 'Guardian', which uses calcium formate as a 'powerful wood conversion agent', was removed from sales in early 2010 for unspecified reasons.
Oil-borne preservatives
These include pentachlorophenol ("penta") and creosote. They emit strong petrochemical odors and are generally not used in consumer products. Both of these pressure treatments routinely protect wood for 40 years in most applications.
Kreos-tar coal
Creosote was the first wood preservative that gained industrial importance over 150 years ago and is currently still widely used to protect industrial wood components where long life is important. Creosote is a tar-based preservative commonly used for power lines and rail links (UK: railway sleep). Creosote is one of the oldest wood preservatives, and originally derived from wood distillates, but now, almost all creosots are made from coal tar distillation. Creosote is regulated as a pesticide, and is not usually sold to the general public.
Linseed oil
In recent years in Australia and New Zealand, linseed oil has been incorporated into preservative formulations as a solvent and water repellent for "envelope" wrapping wood. This involves treating only the 5 mm outside of the cross section of the wood member with a preservative (eg, permethrin 25:75), leaving an untreated core. Although not as effective as the CCA or LOSP methods, envelope treatments are significantly cheaper, because they use far less preservatives. The major preservative producer adds a blue (or red) dye to the envelope treatment. The blue wood is for use in the South Tropic of Capricorn and red for elsewhere. Colored dyes also show that wood is treated for resistance to termites/white ants. There is an ongoing promotional campaign in Australia for this type of treatment.
Other emulsion
Light organic solvent preservatives (LOSP)
This wood-care class uses a white spirit, or light oils such as kerosene, as a solvent carrier to produce preservative compounds into the wood. Synthetic pyrethroid is usually used as an insecticide, such as permethrin, bifenthrin or deltamethrin. In Australia and New Zealand, the most common formulations use Permethrin as an insecticide, and Propaconazole and Tebuconazole as fungicides. While still using chemical preservatives, this formulation does not contain heavy metal compounds.
With the introduction of strict volatile organic compound laws (VOCs) in the European Union, LOSP has a disadvantage due to the high costs and long processing times associated with steam recovery systems. LOSPs have been emulsified into water-based solvents. Although this significantly reduces VOC emissions, wood swells during treatment, eliminating many of the advantages of LOSP formulations.
Epoxy
Various Epoxy resins are usually diluted with solvents such as acetone or MEK can be used to preserve and seal wood.
New technology
Wood asset
Wood chemical modification at the molecular level has been used to improve its performance properties. Many chemical reaction systems for wood modification, especially those using different types of anhydrides, have been published; However, the reaction of wood with acetic anhydride has been the most widely studied.
The physical properties of each material are determined by its chemical structure. Wood contains an abundance of chemical groups called free hydroxyl . The free hydroxyl group readily absorbs and releases water according to the changing climatic conditions in which they are exposed. This is the main reason why wood dimensional stability is affected by swelling and shrinkage. It is also believed that the digestion of wood by enzymes begins at free hydroxyl sites, which is one of the main reasons why wood is susceptible to decay.
Acetylation effectively converts free hydroxyl in wood into acetyl groups. This is done by reacting the wood with acetic anhydride, derived from acetic acid. When the free hydroxyl group is converted to an acetyl group, the ability of wood to absorb water is greatly reduced, making the wood more stable dimensionally and, as it is no longer easily digested, is highly durable. In general, softwoods naturally contain 0.5 to 1.5% acetyl content and longer-lasting hardwoods from 2 to 4.5%. Acetylation takes timber far beyond this level with the appropriate benefits. This includes extending the life of the coating because acetylated wood acts as a more stable substrate for paints and translucent linings. Acetylated wood is non-toxic and has no environmental problems associated with traditional preservation techniques.
Wood acetilasi was first performed in Germany in 1928 by Fuchs. In 1946, Tarkow, Stamm and Erickson first described the use of acetylated wood to stabilize wood from swelling in water. Since the 1940s, many laboratories around the world have seen the acetylation of various types of wood and agricultural resources.
Regardless of the many studies on the modification of wood chemistry, and, more specifically, on acetylation of wood, commercialization does not come easily. The first patent on acetylation of wood was filed by Suida in Austria in 1930. Then, in 1947, Stamm and Tarkow filed a patent on the acetylation of wood and the board using pyridine as a catalyst. In 1961, Koppers Company published a technical bulletin about acetylation of wood that did not use catalysis, but with organic cosolvent. In 1977, in Russia, Otlesnov and Nikitina approached commercialization, but the process was discontinued, possibly because the cost effectiveness could not be achieved. In 2007, Titan Wood, a London-based company, with production facilities in the Netherlands, achieved cost-effective commercialization and started large-scale production of acetate wood under the trade name "Accoya".
Natural preservatives
Copper plating
Copper coating or copper sheathing is a wood coating practice that is usually a ship's hull with copper metal. Because copper metal is both repellent and toxic to fungi, insects such as termites, and bi-valve this sea will preserve the wood and also act as an anti-fouling step to prevent aquatic life from sticking to the hull and reduce ship speed and maneuverability.
Natural decaying forests
These species are resistant to decay in their nature, due to the high levels of organic chemicals called extractive , especially polyphenols. Extracts are chemicals stored in tree trunks of certain tree species because they turn sapwood into wooden terraces. Huon pine ( Lagarostrobos franklinii ), merbau ( Intsia bijuga ), iron ( Eucalyptus spp.), T? Tara (Podocarpus totara ), purple ( Vitex lucens ), kauri ( Agathis australis ), and many cypresses, such as beach redwoods ( Sequoia sempervirens ) and the western red cedar ( Thuja plicata
Huon pines were used for ship hulls in the 19th century, but the excessive harvest and the very slow growth rate of Huon pine trees made this a special wood. Huon pine is very decaying, trees that fell down years ago are still commercially valuable.
Merbau is still a popular deckwood and has a long life in applications on the ground, but it is logged in an unsustainable and overly hard and fragile way for general use.
Ironbark is a great choice if available. It is harvested from old plants and plantations in Australia and is very resistant to decay and termites. It is most commonly used for fence posts and house stumps.
The red cedar tree ( Juniperus virginiana ) and the black robinia ( Robinia pseudoacacia ) have long been used for rotting resistant fence rails and rails in the eastern United States, with black locusts planted in modern times in Europe. Beach redwoods are commonly used for similar applications in the western United States.
TÃ ¢ â,¬tara and puriri were used extensively in New Zealand during the European colonial era when native forests were "mined", even as many fence posts still operate. T? Tara used by M? Ori to build great waka (canoe). Today, they are special wood as a result of their scarcity, although lower grade stock is sold for landscape use.
Kauri is a great wood to build the hull and boat deck. It is also a special wood and ancient log (over 3,000 years old) that has been mined from the swamp used by carpenters and furniture makers.
The natural endurance or decay and insect resistance of wood species is always based on the pith (or "truewood"). Gubal of all types of wood should be considered not durable without preservative treatment.
Tung oil
Tung oil has been used for hundreds of years in China, where it is used as a preservative for wooden vessels. Oil penetrates wood, and then hardened to form an impermeable hydrophobic layer up to 5 mm into the wood. As a preservative, it is effective for exterior work above and below ground, but a thin layer makes it less useful in practice. It is not available as a pressure treatment.
Heat treatment
By surpassing the kiln of wood drying, heat treatment can make wood more durable. By heating the wood to a certain temperature, it is possible to make wood fiber less attractive to insects.
Heat treatment can also improve the wood properties with respect to water, with lower moisture humidity, less humidity deformation, and weather resistance. It's weatherproof enough to be used unattended, on the facade or at the kitchen table, where wetting is expected.
There are four similar heat treatments - Westwood, developed in the United States; Retiwood, developed in France; Thermowood, developed in Finland by VTT; and Platowood, developed in the Netherlands. These processes mengautoclaft the processed wood, subjecting it to pressure and heat, together with nitrogen or moisture to control drying in the gradual treatment process from 24 to 48 hours at a temperature of 180 ° C to 230 ° C depending on the wood species. These processes increase the durability, dimensional stability and hardness of wood maintained by at least one class; However, the treated wood is dark, and there is a change of certain mechanical characteristics: In particular, the modulus of elasticity increases by 10%, and the breaking modulus is reduced by 5% to 20%; thus, treated wood requires drilling to nail not to cut wood. Some of these processes cause less impact than others in their mechanical effect on treated wood. Wood treated by this process is often used for coatings or upholstery walls, floors, furniture and windows.
For pest controls that may be buried in wooden packaging (ie crates and pallets), ISPM 15 requires heat treatment of wood up to 56 ° C for 30 min to receive HT stamps. This is usually necessary to ensure the killing of pine nematode nematodes and other types of wood pests that can be transported internationally.
Mud treatments
Wood and bamboo can be buried in mud to help protect them from insects and decay. This practice is widely used in Vietnam to build farmhouses consisting of wooden structural skeletons, bamboo roof tiles and bamboo with mud mixed with rice straw for walls. While woods in contact with the soil will generally break down faster than the wood that does not come into contact with it, it is possible that the dominant clay soil in Vietnam provides a degree of mechanical protection against insect attack, which compensates for the accelerated decay rate.
Also, since wood is only subject to bacterial decay under a certain temperature range and water content, soaking it in water saturated mud can slow decay, by saturating internal wood cells beyond their moisture decay range.
Application process
Introduction and history
Perhaps the first attempt to protect wood from decay and insect attack consists of brushing or scrubbing preservatives onto the treated wooden surface. Through trial and error preservatives and the most effective application process is slowly determined. In the Industrial Revolution, demands for things like the telegraph pole and railway links (England: railroads) helped sparked a burst of new techniques that emerged in the early 19th century. The sharpest rise in discovery occurred between 1830 and 1840, when Bethell, Boucherie, Burnett and Kyan made history of wood preservation. Since then, many processes have been introduced or existing processes have been improved. The goal of modern wood conservation is to ensure deep and uniform penetration at a reasonable cost, without harm to the environment. The most widespread application process today is those who use artificial pressure through a lot of effectively treated wood, but some species (eg spruce, Douglas-fir, larch, hemlock and cypress) are highly resistant to impregnation. By using incising, this wood treatment has been successful but at a higher cost and results are not always satisfactory. One can split the method of pickling woods roughly into a non-pressure process or pressure process.
Unmanageable process
There are many non-pressure processes for treating woods that vary mainly in their procedures. The most common of these treatments involves preserving applications by brushing or spraying, dipping, soaking, steeping or by means of hot and cold baths. There are also various additional methods involving charring, applying preservatives in boring holes, diffusion processes and sap transfer.
Brush and spray care
Brushing preservatives is a method that has long been practiced and is often used in today's carpentry workshops. Technological developments mean it is also possible to spray preservatives onto wood surfaces. Some liquids are drawn into the wood as a result of capillary action before the spray flows or evaporates, but unless the penetration is limited penetration and may not be suitable for long-term weathering. Using the spray method, coal tar kreosote, a solution carried by oil and water-borne salt (to some extent) can also be applied. Brush or thorough spray treatment with coal tar kreosote can add 1 to 3 years to pole or pole life. Two or more layers provide better protection than one, but successive layers should not be applied until the previous layer has dried or soaked into the wood. Wood should be spiced before treatment.
Dip
Dipping consists solely of soaking the wood in a creosote or other preservative for a few seconds or minutes. Similar penetration with the brushing and spraying process is achieved. It has the advantage of minimizing handwork. This requires more equipment and a greater amount of preservatives and is not sufficient to treat a lot of small wood. Usually the dyeing process is useful in the care of window and door belts. Treatment with copper salt preservatives is no longer permitted by this method.
Steep
In this process the wood is submerged in a mixed tank of water preservative, and left to soak for a longer period of time (several days to weeks). This process was developed in the 19th century by John Kyan. The depth and retention achieved depend on factors such as species, wood moisture, preservative and the duration of immersion. The majority of absorptions occur during the first two or three days, but will continue at slower speeds for an indefinite period. As a result, the longer the wood can be left in the solution, the better the treatment will be. When treating the dried herbs, both water and preservative salt permeate into the wood, so it is necessary to season the wood for a second time. Shipments and poles can be treated directly in an endangered area, but should be treated at least 30 cm (0.98 ft) above the ground in the future.
The depth obtained during the regular brewing period varies from 5 to 10 mm (0.20 to 0.39 inches) to 30 mm (1.2 inches) by pine resin. Because of low absorption, the strength of the solution should be stronger than in the pressure process, about 5% for spicy wood and 10% for greenwood (because its concentration slowly decreases as the chemicals spread to the wood). The strength of the solution should be continuously controlled and, if necessary, corrected with salt additives. After the wood is removed from the treatment tank, the chemical will continue to spread in the wood if it has enough moisture content. The wood must be weighed and stacked so that the solution can reach all surfaces. (Saw material stickers should be placed between each layer of the board.) This process finds minimal usage although previously known in continental Europe and the UK.
Kyanizing
Named after John Howard Kyan, who patented this process in England in 1833, Kyanizing consists of wooden sediments in 0.67% mercury chloride preservative solution.
Gedrian's Bath
Patented by Charles A. Seely, this process achieves treatment by immersing spicy wood in a conserved hot and cold preservative. During a hot bath, the air expands on the wood. When the wood turns into a cold bath (preservatives can also be altered), some vacuum is made inside the cell lumens, causing preservatives to be drawn into the wood. Some penetrations occur during a hot bath, but most occur during a cold shower. This cycle is repeated with significant time reductions compared to other brewing processes. Each bath can last 4 to 8 hours or in some cases longer. The preservative temperature in hot water should be between 60 to 110 ° C (140 ° to 230 ° F) and 30 ° to 40 ° C (86 ° to 104 ° F) in a cold bath (depending on preservatives and tree species). The average penetration depth achieved by this process ranges from 30 to 50 mm (1.2 to 2.0 inches). Both preservative oils and water-soluble salts may be used with this treatment. Due to longer treatment periods, this method found little use in the current commercial timber conservation industry.
Preservative Precipitation
As described in the Uhlig Corrosion Guidebook, this process involves two or more chemical baths undergoing reactions with wood cells, and results in settling deposition into wood cells. The two chemicals commonly used in this process are Ethanolamine Copper, and Sodium Dimethyldithiocarbamate, which reacts to precipitate Copper Dimetyldithiocarbamate. Preserved preservatives are highly resistant to leeching. Since its use in the mid-1990s, it has been discontinued in the United States, but has never seen commercialization in Canada.
Process pressure
The process of pressure is the most permanent method today in preserving wood life. The process of pressure is the process by which the treatment is carried out in a closed cylinder with pressure or vacuum applied. These processes have a number of advantages over non-pressure methods. In many cases, deeper and more uniform penetration and higher preservative absorption are achieved. Another advantage is that maintenance conditions can be controlled so that retention and penetration may vary. This pressure process can be adapted to large-scale production. The high initial cost of equipment and energy costs is the greatest loss. This treatment method is used to protect structural bonds, poles and structures and find current worldwide use. The various pressures used today are different in detail, but the general method is in all cases the same. Treatment is done in a cylinder. The wood is loaded into a special tramcar, called buggies, or bogies, and into the cylinder. These cylinders are then set under frequent pressure with the addition of higher temperatures. As a final treatment, vacuum is often used to extract excessive preservatives. This cycle can be repeated to achieve better penetration.
LOSP treatment often uses a vacuum impregnation process. This is possible because of the lower viscosity of the spirited-white carrier used.
The full cell process
In a full cell process, the goal is to store as much of the liquid absorbed into the wood during the period of pressure, leaving the maximum preservative concentration in the treated area. Typically, aqueous solutions of preservative salts are used with this process, but it is also possible to impregnate wood with oil. The desired retention is achieved by changing the power of the solution. William Burnett patented this development in 1838 from cell impregnation filled with water solutions. Patents cover the use of zinc chloride on water, also known as Burnettizing. The cell process was filled with oil patented in 1838 by John Bethell. The patent describes the injection of tar and oil into the wood by applying pressure in a closed cylinder. This process is still used today with some improvements.
Fluctuation pressure process
Contrary to the process of static cells and empty cells, the fluctuation process is a dynamic process. With this process, the pressure inside the impregnation cylinder changes between pressure and vacuum within a few seconds. There is an inconsistent claim that through this process it is possible to reverse the closure of a hole by a pine tree. However, the best results achieved by this process with spruce do not exceed deeper penetration than 10 mm (0.39 inches). Special equipment is required and therefore higher investment costs occur.
Boucherie Process
Developed by Dr. Boucherie from France in 1838, this approach consisted of attaching a bag or container preservative solution to a stand or a freshly cut tree with bark, branches, and leaves still attached, thus injecting the liquid into the sap stream. Through transpiration the moisture from the preservative leaves is pulled up through the sapwood of the tree trunk.
The modified Boucherie process consists of placing the freshly cut and unpeeled wood on a decreasing decline, with a slightly elevated stump, then tightening waterproof covering the cap or drilling a number of holes to the end, and inserting copper sulphate or other waterborne preservatives into in a lid or hole from an elevated container. Preservative oils tend not to penetrate satisfactorily with this method. The hydrostatic pressure of the liquid forces the preservative to lengthen inward and through the sap, thereby pushing the sap out of the other end of the wood. After a few days, the sapwood is fully impregnated; unfortunately little or no penetration occurs in the pith. Only green wood can be treated this way. This process has found many uses for impregnating poles and also larger trees in Europe and North America, and has experienced a revival of use to impregnate bamboo in countries such as Costa Rica, Bangladesh, India and the state of Hawaii.
High-pressure sap transfer system
Developed in the Philippines, this method (abbreviated HPSD) consists of a cylindrical pressure cap made of a 3 mm thick 3 mm thick steel plate secured with 8 sets of bolts, 2-HP diesel engine and pressure regulator with 1.4-14 kg/soup> 2 . The lid is placed on the stump post, the tree or bamboo and the preservative is forced into the wood with pressure from the machine.
Incising
First tested and patented by Kolossvary, Haltenberger and Berdenich of Austria in 1911 and 1912 (US patents 1,012,207 and 1,018,624) with some improvements from OPM Goss, DW Edwards and JH Mansfield, among others, the process consisted of a shallow, holes in the surface of the material to be treated, resulting in deeper and more uniform penetration of prevention can be obtained. The term incising or perforating comes from the Latin incidere , the compound in and caedere (for cutting). The incisions made from the sawed material are usually parallel to the wood grain. This process is common in North America (since the 1950s), where pine and spruce products of various species are prepared before treatment. This is particularly useful for wood resistant to side penetration, but allows pickling preservation along the granules. In the area where it is produced, it is common practice to incise all Douglas-firs 3 in (76 mm) or thicker before treatment.
Unfortunately, impregnation of pine trees, the most important structural woods in large areas of Europe, has shown that unsatisfactory depth of care has been achieved by impregnation. Maximum penetration of 2 mm (0.079 inches) is not enough to protect the wood in the weather position. The current incising machine basically consists of four rotating drums fitted with a tooth or a needle or with a laser burning an incision into the wood. Preservatives can spread along grains of up to 20 mm (0.79 inches) in radials and up to 2 mm (0.079 inches) in tangential and radial directions.
In North America, where smaller wood dimensions are common, a 4 to 6 mm incubation depth (0.16 to 0.24 inches) has become the standard. In Europe, where larger dimensions are widespread, an incision depth between 10 to 12 mm (0.39 to 0.47 inches) is required. The incision is seen and is often considered a wooden fault. The incision by the laser is significantly smaller than the spokes or the needle. The cost for each type of process is roughly for the converse/inclusive all incising EUR0.50/m 2 , with laser incising EUR3.60/m 2 and with the incision of the needle EUR1.00/m 2 . (Figures are from 1998 and may vary from current prices.)
Microwave
An alternative increases wood permeability using microwave technology. There are some concerns that this method may affect the material's structural performance. Research in this field has been conducted by the Cooperative Research Center at the University of Melbourne, Australia.
Charring
Timber drilling produces fireproof, insect-proof, and weather-resistant surfaces. The wood surface is ignited using a hand-held burner or moving slowly across the fire. The charred surface is then cleaned by using a steel brush to remove loose parts and to expose the grain. Oil or varnish may be applied if necessary. In Japan this traditional technique is called yakisugi or sh? ban sugi .
See also
- Viance technology and advanced wood preservative services
- Chemical Koppers and ingredients company
- The leaked house crisis in New Zealand
- Nanotoksikologi
References
External links
Non-CCA wood preservative
- Non-CCA Timber Preservative: Guide for Selected Resources - National Pesticide Information Center
Arsenate
- Case Study in Environmental Medicine - Arsenic Poisoning
- CPSC Test Layers to reduce arsenic emissions from pressured timber
Borate
- Borrate Processed Wood in Modern Applications
- Borat Analysis as Insecticide in Wood
Sodium silicate
- Short snippet from The Columbia Encyclopedia
- Albite (sodium aluminum silicate) mineral
Miscellaneous
- FAQ from the Forest Products Laboratory of the US Forest Service
- Information from the U.S. Environmental Protection Agency
- The American Wood Protection Association (AWPA, formerly the American Wood Watch Association)
- American Lumber Standards Committee (ALSC)
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Source of the article : Wikipedia
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