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Wood preservation All measures that are taken to ensure a long life of wood. A preservative is a natural or synthetic chemical that is added to wood, to prevent decomposition by microbial growth or by undesirable chemical changes.

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Introduction Treatment of wood has been practised at the beginning of recorded history. For example the Bible in Genesis, 6:13-14 “And God said unto Noah… make thee an ark of gopher wood; rooms shalt thou make in the ark, and shalt pitch it within and without with pitch.” ancient Greece during Alexander the Great’s rule, where bridge wood was soaked in olive oil. The Romans also protected their wood by brushing their ship hulls with tar.

Breaf history : 

4000bc – god tells noah to use tar in building the ark. 2000bc – gilgamesh epic – tar is poured over wood. 484-424bc – aluminium potassium sulphate used as fire retardant. 356-323bc – wood for bridges treated against olive oil (alexander) 33-14bc – vitruvious pollio- charing & coating olive oil. 23-79ad – plinius secundus – cedar oil resistant to insect & decay. statue of diana in ephesus impregnated with nard oil. Breaf history

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Fourth century – palladius – preservation with salt water. 1445 – franckensepiegel – timber for a church is boiled in brine. 1452-1419 – leonardo da vinci – paintings panel & carvings are coated with mercury (ii)chloride, arsenic(iii)oxide. 1469-1524 – vasco da gama – ship building chared against ship worm. 1500 – termites controlled with mercury (ii)chloride, arsenic(iii)oxide. 1666 – journal jes savans- complete many wood preservation methods 1718 – hiarne awarded patent in sweden – wood balm based on copper or iron sulphate. 1st commercially prepared wood preservative.

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1735 – bark borer controlled by pepper,laurel &myrrh in wine.also with ox urine & vineger. 1756 – use of plant tar & extractivesas preservatives in england and america 1767 – boissieu & bordenare- recommend copper sulphate . 1770 – sir john pringle- list of wood preservatives published in england 1784 - royal society of arts: promise of a gold medal for discovery of cause and control of decay in buildings. 1800 – pyrethrum known as an insecticide. 1812 – kyan starts research in mercury ii chloride as a preservative. 1815 – thomas wade- zinc chloride as a preservative.

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1825 – faraday –discovery of hexa chloro cyclo hexane (HCH) 1832 – kyan – british patent for vat treatment with mercury ii chloride aqueous sollution. Beginning of modern wood preservation. 1836 – franz mol – patent for coal tar creosote. Coin the word creosote. 1838 – john bethel - pressure impregnation with creosote oil. 1840 – dalmatian insect powder – anna rosauer 1841 – synthesis of pentachlorophenol. 1863 – last use of mercuri chloride – toxicity- replaced. 1874 – o.zeidler – synthesis of DDT.

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1881 – pyrithrem used against g.hoppers – callifornia – it cultivation introduced in japan. 1887 – thompson - french patent of impregnation of wood with fluor compounds. 1901 – malenkovic - patent of preservation of wood with fluor compounds. 1913 – chramium compounds – non leachable preservatives. 1915 – 1st use of 1,4 dichloro benzene against wood borers. 1916-1918 – austria –annualy coted with petroleum & hexa chloro ethane. 1920 – mono & di chloronapthalene are suggested as wood preservatives. 1933 – a british patent for boron compounds.

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1935 – research on fungicidal effectiveness on chlorophenols. 1939 – muller ;discovery of insecticidal effect of DDT. 1945 – DDT used as insecticides in great britain. 1947-53 – lindane & PCP used as biocides in germany. 1948 – production of synthetic pyrethroid in U.S.A 1959 – tributyltin oxide(TBTO) used as a fungicide in great britain. 1976-78 – testing of synthetic pyrethroid against wood destroying insects.

History of wood seasoning in india : 

Scientific seasoning in india started during first world war(1914-18)- for meet the demand of gun carriages, ammunition boxes. Seasoning industory came during the second world war(1940-45) The seasoned industry made sustained progress with the industrialization of the country after independene. During 1927- 40 Seasoning industry closely linked with seasoning branch of FRI. FRI gives, basic data, technical tips for establishment of seasoning industry, knowledge of shrinkage of wood at diff temperature, method of preventing excessive shrinkage, air seasoning behaviour of 250 spp,method of stacking. History of wood seasoning in india

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During 1940- 66 Determination of data on equilibrium moisture content attained by wood in diff climatic zones of the country Basic schedules were evolved for kiln drying of about 150 commercial indian spp Blue prints &specifications are developed ofr steam heated over head internal fan type of kilns.resistant type moisture meter was developed Based on this information national standards for seasoning were formulated & outlines of schemes for kiln seasoning instalation were prepared for the benefit of the industry. 1945 – indegenous kiln equipment manufacturing industry was established. 1956 – 100 new kiln installation with capacity of 0.102mill cu.m/annum.

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From 1967 onward, Research is done for Low cost methods for seasoning Improve kiln design for efficiency & cost reduction. Develop methods for accelerated degrade-free seasoning of refractory hardwoods. And developed Solar heated kiln with capacity of 7 cu.m. Improve uniformity air circulation by simple changes in chamber profile. End mounted fan type “screen” dryer has been evolved for a stacking capacity of 5.67cu.m(200cft) Electrically heated kiln was introduced. Where fuel cost is high

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Chemical methods urea for check free drying of thick-section tent mallet heads. Polythene glycol-1500 for check free drying of wooden handicrafts. PEG-600 for defect free drying of round bamboo for handicraft 1990 – dehumidification drying process was introduced.

History of some preservation methods : 

Wood Acetylation The acetylation of wood was first done in Germany in 1928 by Fuchs. In 1946, Tarkow, Stamm and Erickson first described the use of wood acetylation to stabilize wood from swelling in water. Since the 1940’s, many laboratories around the world have looked at acetylation of many different types of woods The first patent on the acetylation of wood was filed by Suida in Austria in 1930. Later, in 1947. Stamm and Tarkow filed a patent on the acetylation of wood and boards using pyridine as a catalyst. In 1961, the Koppers Company published a technical bulletin on the acetylation of wood using no catalysis but with an organic cosolvent History of some preservation methods

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Chromated copper arsenate (CCA) An extremely common preservative originally developed in the 1930s at the Forest Research Institute in Dehra Dun, India by Dr Sonti Kamesam. Dr Kamesam sold the patent rights for what he originally called ASCU salts to the Bell Telephone Company of the USA. The acronym "CCA" is believed to have come into popular use for this product in the 1950s. On 1 January 2004 the Environmental Protection Agency (EPA) in a voluntary agreement with industry began restricting the use of CCA in treated timber in residential and commercial construction, Sodium silicate-based preservatives Sodium silicate is produced by fusing sodium with sand or heating both ingredients under pressure. It has been in use since the 1800s.

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Bifenthrin spray preservatives water-based bifenthrin preservative has been developed to improve the insect resistance of timber. As this preservative is applied by spray, it only penetrates the outer 2mm of the timber cross-section. Steeping In this process the wood is submerged in a tank of water-preservative mix, and allowed to soak for a longer period of time (several days to weeks). This process was developed in the 19th century by John Kyan. Kyanizing Named after John Howard Kyan, who patented this process in England in 1832, Kyanizing consists of steeping wood in a 0.67% mercuric chloride preservative solution.

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Osmosis process In this process, first developed in Germany, the preservative is applied to the surface of green wood in the form of a cream or paste. Full-cell process William Burnett patented this development in 1838 of Full-Cell Impregnation with water solutions. The patent covered the use of zinc chloride on water basis, also known as Burnettizing. Full-Cell Process with oils was patented in 1838 by John Bethell. His patent described the injection of tar and oils into wood by applying pressure in closed cylinders.

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Boucherie process Developed by Dr. Boucherie of France in 1838, this approach consisted of attaching a bag or container of preservative solution to a standing or a freshly cut tree with bark, branches, and leaves still attached, thereby injecting the liquid into the sap stream. Through transpiration of moisture from the leaves the preservative is drawn upward through the sapwood of the tree trunk. Incising First tested and patented by Kolossvary, Haltenberger, and Berdenich of Austria in 1911 and 1912 this process consists of making shallow, slit-like holes in the surfaces of material to be treated, so that deeper and more uniform penetration of preventative may be obtained.

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Microwaving An alternative method of increasing the permeability of timber involves using microwave technology. Ongoing research in this area is being conducted by the Cooperative Research Centre at the University of Melbourne, Australia. REFERENCE Wood seasoning technology (c.n pandey& v.k.jain) linkinghub.elsevier.com/ www.fao.org/docrep en.wikipedia.org/wiki/Timber_treatment

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