Different ways of seasoning wood home guides sf gate. Chemical seasoning agents can reduce the strength of wood and sometimes cause problems in gluing and. In chemical seasoning, the timber is immersed in a solution. Timber classification, types, defects in timber civil. The chromium acts as a chemical fixing agent and has little or no preserving properties. Artificial seasoning of timber seasoning by boiling. The term seasoning carries the meaning that the wood had been exposed to one or more seasons of weather. Timber its properties, classifications, parts, seasoning. When the drying is done in a kiln, the product is known as kilndried timber. This method is said to cause less shrinkage but it is expensive to use, and reduces the strength and elasticity of the timber. Trees gives us the timber which is converted into required form and finally used. Seasoning of timber or simply timber seasoning is the process of drying timber or removing moisture or sap, present in a freshly felled timber, under more or less controlled conditions. Water seasoning on account of the time required to season timber in the natural way, various methods have been tried to effect the same purpose in a shorter time. Before reaching this final stage, timber comes across many critical stages like growing without defects, cutting at the right time, seasoning, converting and using.
Seasoning of timber and drying of wood types and methods. Article views are the countercompliant sum of full text article downloads since november 2008 both pdf and html across all institutions and individuals. What is seasoning of timber type of seasoning of timber benefit. Chemical seasoning university of florida digital collections. The united states forest products laboratory at madison, wisconsin, was the first to enter the. The interior surface of timber dries in advance of exterior one and chances of formation of external cracks are reduced. May 11, 2007 in some cases, microwave energy delivery can be combined with low ambient pressure to produce optimal seasoning speeds. Chemical seasoning of wood and preservation methods of. Salts carried in volatile solvent other than water. The salt solution used is such that it is capable of absorbing water from the timber. In this way surface checking is avoided because the surface fibers are not stretched as they. The application of a hygroscopic chemical to green wood followed by air seasoning or kiln drying is called chemical seasoning. To make a correct percentage of shrinking of woods. Types of defects in timber as a construction material.
Sep 30, 2015 timber cannot be used for carpentry joinery immediately after it converted as there is a lot on moisture present in thr wood. So, artificial seasoning of timber is developed nowadays. Jun, 2014 the disadvantages of seasoning is that some seasonings contain a chemical called tcp and this may be detrimental to health if over exposed. In this method high frequency alternate electric current is passed through timber. The present process involves comparatively short treating periods. Different types of defects occur in timber at these various stages. In place of boiling water, the timber may be exposed to the action of hot steam. Instead of boiling water hot steam may be circulated on timber. Salt seasoning is the submersion of wood in a solution of urea, sodium nitrate, all of which act as dehydrating agents. The preliminary treatment by chemical seasoning ensures uniform seasoning of outer and inner parts of timber. Sep 06, 2019 in this process, timber surface is cleaned and it is coated with a dilute solution of sodium silicate. Chemical seasoning consists of treating green wood withaiygroscopic chemi. Building material mcqs questions and answers on timber.
Jul 30, 2018 it is then removed from the highpressure vessel and laid out to dry. Before shipping, it is essential that treated wood has stopped dripping. Seasoning is the process of drying timber to remove the bound moisture contained in walls of the wood cells to produce seasoned timber. Apart from structural wood preservation measures, there are a number of different preservatives and processes also known as timber treatment, lumber treatment or pressure treatment that can extend the life of wood, timber, wood structures or engineered wood. If you mean lumber or boards, the lumber needs to be stacked in a way. Electrical seasoning involves running an electric current through the lumber causing heat. Seasoning is the process of drying timber to remove the bound moisture.
Among the hygroscopic chemicals which have been suggested for use in the chemical seasoning of green lumber are such inorganic salts as sodium chloride. Seasoning of timber is also achieved by boiling it in water for 3 to 4 hours. Artificial or kiln seasoning is a quicker method of seasoning timber t the desired moisture content under highly controlled conditions. If full advantage be taken of the chemical seasoning the. Sep 02, 20 artificial or kiln seasoning is a quicker method of seasoning timber t the desired moisture content under highly controlled conditions.
In this method timber is subjected to hot air in air. Seasoning starts immediately after the cutting of green trees even in. When the chemical has been absorbed, the lumber is piled for seas oning. What is seasoning of timber type of seasoning of timber. The wood is removed from the unit after the 21 hour cycle and then dried in the air under a coarse canvas cover. It is then taken out and seasoned in the ordinary way. Among the other methods of seasoning of timber and wood, the chemical seasoning and electric seasoning are of some importance. Seasoning is important as wood contains moistures that has to be removed in order to obtain satisfactory performance from the wood. In this method timber is immersed in water and then water is boiled for 3 to 4 hours. A 20% reduction in overall weight of wood products treated in this way will give similar percentage savings in the cost of shipping undried products. Maximise performance of timber intuitive understanding of timber behaviour physiology of timber fibres, cells, grain, growthrings. Ese seasoning of timber by naturally and artificiallyboiling, chemical, electrically, kiln and water seasoning in hindi. In case of chemical seasoning, timber is stored in suitable salt solution for some time.
Seasoning of timber artificial and natural methods. Lec54eseseasoning of timber by naturally and artificially. It fre quently happens that in the sapwood, and sometimes in the heart wood, the weight of the water is more than the weight of the wood substance itself. An aqueous solution of chemical salts like common salt or urea have low pressure. After sufficient immersion, the timber is removed and left for drying. A french process of electrifying timber is stated to give perfect seasoning in a single night. Chemical seasoning salt seasoning timber is immersed in a solution of salt. A creamlike paste of slaked fat lime is then applied and finally, a concentrated solution of silicate of soda is applied of the timber surface. Generally, chemical seasoning includes storage of timber in a suitable salt solution for a certain period. If the outer layers of timber are treated with such chemicals the vapour pressure will reduce and a vapour pressure gradient is created. Jun 06, 20 advantages and disadvantages of timber houses june 6, 20 erin emanuel 5 comments timber has been around longer than we have, and since the prehistoric man first stepped foot out of his cave, it became the widest spread material for building shelters. Wood treatment plant timber treatment plant latest price. The principle is that vapor pressures of aqueous solutions of salts ie common salt have lower vapor pressure than pure water.
In this method, the timber is immersed in a solution of suitable salt. In this method, the wood is immersed in a suitable salt solution. The art of seasoning of timber is to extract the moisture under controlled conditions as nearly as possible at a uniform rate from all parts of timber and to leave the remaining moisture, that cannot be extracted. The time required for this seasoning is 30 to 40 days. Chemical seasoning if the outer layers of timbers are. We offer seasoning plant, which is as per ispm 15 standerd and used for drying and seasoning of wood that prevents from defects like warping, cracking, splitting etc. Seasoning is the reduction of moisture content of timber to that of thesurrounding air sydney area approx.
Seasoning of timber methods of timber seasoning ravi dhami. Apr 11, 2020 ese seasoning of timber by naturally and artificiallyboiling, chemical, electrically, kiln and water seasoning in hindi. In the chemical seasoning of wood with aqueous solutions of hygroscopic organic chemicals the step which consists of incorporating a watersoluble chlorophenolate in the treating so. Seasoning of timber reason methods benefits civil engineering. Wooden seasoning chemical plant boiler and wooden termite. Chemical seasoning chemical seasoning is used for highvalue applications where the timber is required to be completely free of surface checks e. When the drying is done in a kiln, the product is known as kilndried timber or lumber, whereas air drying is the more traditional method. For example, wood can be treated with chemicals to replace the hydroxyl groups with. These generally increase the durability and resistance from being destroyed by insects or fungus. Seasoning of timber is done to fulfill some specific requirement. In general, the defects in timber are mainly due to. Seasoning is the process of removing the moisture content from wood to minimize structural problems when used in construction or to provide less smoke and more uniform combustion when used as. The chemical is used to reduce or prevent surface checking during seasoning, rather than to accomplish actual drying or.
The different ways that seasoning in wood can be achieved. Then the timber is allowed to dry under a shed having free circulation of air. Read more progressive seasoning compartmental seasoning chemical. Chemical seasoning is used for highvalue applications where the. By chemical seasoning methods, therefore, it is possible to dry from the inside out and to prevent the surface fibers from becoming sufficiently dry to induce them to shrink. Timber can also be made fire proof to some extent by giving external coats and treatment of fire retarding chemicals like sodium silicate, sodium arsenate or borax. The wood spice process is the process by which the moisture in the wood is reduced to the required level by reducing the moisture content, strength, elasticity, and durability properties are developed. The interior surface of timber dries in advance of exterior one and chance of formation of external cracks are decreased. More than half the weight of freshly cut timber consists of moisture or sap. There are two main ways of seasoning timber, natural air and artificial kiln. Seasoning of timber natural seasoning artificial seasoning water seasoning air seasoning seasoning by boiling chemical seasoning kiln seasoning. A oily preservatives coaltar is the best known most widely used preservative obtained from bituminous coal available in many grades gives satisfactory results. Wood drying reduces the moisture content of wood before its use.
Timber, lime, brick and mortar study notes for civil engineering. Chemical seasoning is used for highvalue applications where the timber is required to be completely free of surface checks e. Seasoning of timber or drying of wood wood drying also seasoning lumber or wood seasoning reduces the moisture content of wood before its use. In this method, the timber piece to be seasoned is treated with a chemical solution like sodium. Freshly felled timber contains moisture 100 to 200% of its dry weight.
In this sense, chemical seasoning of lumber is most recent in its researches. With leadplate eloctrodes on each side, the timber is placed in a. Oct 11, 2018 in this method, the timber is immersed in a solution of suitable salt. One of the best of these is to immerse the timber in water as soon as it is cut down, and after it has remained about a fortnight in water, but not more, to take it out, and dry it in. In this technique through timber high frequency alternate electric current is passed resistance to. In chemical seasoning carbon dioxide, ammonium carbonate or urea are used as agents for seasoning, those are applied in dry state, the inter surface of timber dries first than outer side. By artificial seasoning, timber is seasoned with in 45 days. This is simply the weight of water contained in a piece of timber compared with the weight of actual woody substance in the same piece. Chemical seasoning as the name itself implies, this method employs chemicals for the seasoning of timber. Seasoning with chemicals forest products laboratory.
If this sap is not removed the timber is likely to warp, crack and shrink. In other words, the timber or lumber is air dried for about one year. Natural seasoning gives good results but takes more time. Newly felled tree contains a considerable quantity of sap. Wood drying also seasoning lumber or wood seasoning reduces the moisture content of wood before its use. The chemical seasoning is also known as salt seasoning. There are 3 main classes of preservatives oily substances insoluble in water watersoluble salts salts carried in volatile solvent other than water. Timber is seasoned to dry out the timber to bring it to a usable and workable condition. Chemical seasoning of timber limited timber development association on.
Here also different methods of artificial seasoning are there and they are as follows. In case of chemical seasoning, timber is stored in suitable salt solution. Followings are the reasons to perform timber seasoning. Seasoning can be achieved in a number of ways, but the aim is to remove water at a uniform rate through the piece to prevent damage to the wood during drying seasoning degrade. In this technique, in a solution of suitable salt the timber is immersed. The lumber and chemical are piled in alternate layers, using from35 to 140 pounds of chemical per 1,000 boardfeet. In this method the timber is cut in suitable sizes and immersed wholly in water, preferably in running water. This document has been scanned from hardcopy archives for. When the drying is done in a kiln, the product is known as kilndried timber or. It is then taken out and then seasoned in an ordinary way. This method is used for seasoning on a larger scale. If full advantage be taken of the chemical seasoning the sur. The salt solution used has the tendency to absorb water from the timber. In ordinary seasoning processes wood dries from the outside in, a fact which explains why wood so often checks in drying.
During this period the sap contained in wood is washed away. Progressive kiln compartment kiln electrical seasoning in this method high frequency alternate electric current is passed through timber. When wood is seasoned with the help of chemical, it is termed as chemical seasoning. The amount of water thus contained varies with the kind of wood, the conditions under which it grew, and the season. By chemical seasoning ensures uniform seasoning of outer and inner parts of timber. In chemical seasoning, the timber is immersed in a solution of suitable salts. Seasoning of timber from day to day, most people have some contact with seasoned timber. When wood is properly chemically seasoned the wood dries from the inside first. What are the disadvantages of wood seasoning answers. Seasoning of timber is the drying of timbers moisture content to a level below 22% by several methods, including air seasoning, kiln seasoning or a combined of both.