To resist the attack of insects, fungi. Therefore, the wood must be dried properly before using it for construction purposes. Plan view of a tier of boards, illustrating the system of alternating short lengths for box piling. The timber is laid out as seen in the diagram below. This process of seasoning timber is the best as it gives very strong and durable timber, but it is extremely slow. But unfortunately timber usually possess different types of defects. Defects due to conversion and seasoning of timber involve shakes, warping, bowing, twist, diamonding, casehardening and honey combing. In semi-kilns, where the temperature is maintained at 110 °F to 120 °F and fans are used to circulate the air, green stock may be dried to 8 to 12 percent moisture content in 3 months. The rise in temperature should be such that the timber retains originals strength and elastic properties. Natural seasoning • (1) Natural seasoning: In this method, the seasoning of timber is carried out by natural air and hence it is also sometimes referred to as air seasoning. Semi-kilns are often nothing more than covered sheds in which the material is piled, but they may often be large enclosed buildings in which low heat and controlled humidity are used to slow the drying process. If seasoning is not done the right way, shrinkage of wood will be irregular, and it will set up internal stresses between the fibers. This process of seasoning timber is the best as it gives very strong and durable timber, but it is extremely slow. During seasoning of timber, exterior or surface layer of the timber dries before the interior surface. Timber seasoning types. Further seasoning needs to be done inside, in heated and ventilated buildings. Seasoned timber is much durable than unseasoned ones. Time required for natural seasoning of timber is around 120 to 180 days. As . Janvi Desai is a Civil Engineer (BE). Seasoning is required for following purposes . Reduce the tendency of the timber to crack, warp, shrink and bend. Timber can be classified into the following three categories depending upon their behavior with respect to cracking, splitting and drying rate: 02. To minimise the cost of handling, transport by decreasing the weight of wood. In natural or air seasoning of timber, the timbers of convenient sizes are stacked under a covered shed in a cross-wise direction in alternate layers to permit free circulation of air. They are then arranged in layers, one above the other. freshJy cut and green. 2) Kiln Seasoning Advantages: Insects are killed during this process, Require little stacking space, Moisture content of the timber may be brought to any desired level Wall Tiles and Floor Tiles: What is the Difference? The properties of timber like dimensional stability, strength, and stiffness – all depend on moisture content of the wood. The basic principle is to stack the timber so that plenty of air can circulate around each piece. The actual time of drying depends upon the size of timber, species of wood and seasonal variations of climate. Movie created by first year Industrial Design students at CPUT The actual time of drying depends upon the size of timber, species of wood and seasonal variations of climate. Seasoning of Timber From day to day, most people have some contact with "seasoned" timber. It is also necessary to support the wood during drying to prevent the lumber from warping during the drying process. When the drying is done in a kiln, the product is known as kiln-dried timber or lumber, whereas air drying is the more traditional method.. Seasoning of timber is also achieved by boiling it in water for 3 to 4 hours. Let us discuss the objectives, advantages, types, and methods of seasoning of timber. 12. She graduated from Government Engineering College – Bharuch in 2017. The process of dying timber or removing moisture or sap, present in a freshly felled tree, is called seasoning of Timber. AIR SEASONING The easiest way, but not the most effective method of seasoning timber, is to stack it outside. Sticks usually are cut 3/4-inch thick. 7. When the timber is freshly felled or cut, it should be place at a place where air may circulate through it. All Rights Reserved. The process has undergone a number of refinements over the years that have made it more efficient and reduced the quantity of wood that was damaged by drying too quickly near the ends in air seasoning. The woods obtained from coniferous trees like deodar, fir, pine, spruce, chir etc. Although it is generally thought that air drying is a gentle method of seasoning timber, it is often severe depending on the time of the year and the species involved. Generally, air seasoning is a slow process. During its lifetime, a tree is subjected to many natural forces that cause defects in the wood. Water seasoning of timber. In the chemical seasoning, green sawn timber is first soaked in a solution of an anti-shrink or anti-shrink cum hygroscopic chemical for an appropriate period. It takes more than six months for timber to season in moderate climates. Advantages of Natural Seasoning of Wood. The timber seasoned by this method is less liable to shrinkage. The salt... Kiln Seasoning. 1) Natural seasoning:-It is the oldest method of seasoning.Non technical person can also be done this method.some natural seasoning are; a) Air seasoning:-This is as yet the most common process of seasoning used through the world.In this process, wood sleepers, planks and scantlings etc cut from the wood logs are stacked in open air. The traditional method of seasoning timber was to stack it in air and let the heat of the atmosphere and the natural air movement around the stacked timber remove the moisture. In Water Seasoning method, timer kept immersed in ponds or running stream for a 3 to 4 weeks. Artificial Seasoning: This is important to tie the pile together and make it less subject to tilting or falling over. Faulty method of seasoning causes serious defects in woods. Over head cover from effects of direct sunlight and driving weather. seasoning of Timber : Method of Seasoning:-The following two methods are commonly used for the seasoning of Timber. Reference [5-7] explained that seasoning involves the evaporation of excess moisture. In other words timber should be dried. Seasoning of Timber • Fresh timber contains about 50% or more of its own dry weight as water. These are: 1. They are natural or air seasoning and artificial or kiln seasoning. Make it suitable for receiving various treatments like paints, preservatives, varnishes etc. The interest costs on holding stock for long periods can prove significant. Warping is a kind of variation from a true or plain surface and may include a one or combination of cup, bow, crook and twist. The objective of air drying wood is to remove the water in wood by exposing all surfaces of each piece of wood to circulating air. It requires the following: The details depend on the size, quantity and species of the timber. Other articles where Air seasoning is discussed: seasoning: …most common seasoning methods are air seasoning and dry-kiln seasoning. Improve strength, hardness and stiffness of timber. Natural Resources FlJRN1lUR.E MANUFACTURING Seasoning of Wood By C A Eckeiman . Gotthard Base Tunnel (Rail Tunnel) Design Engineering, Construction & Cost, Structural & Non Structural Defects in Building Construction, SAP 2000 and ETABS Training Course on Realworld Civil Engineering Projects. An adequate supply of wooden sticks (spacers) will be needed to separate each layer (Figures 1 and 2). This is such an important stage in the drying that it is given a special name, and the term is "fibre saturation point". With the increased use of several secondary species that possesses higher shrinkage than teak, deodar, rosewood etc. Note that the stickers are carefully aligned vertically (Figure 2) so that each layer of lumber will be supported from the base of the pile. When a tree is fresh cut, the wood contains a considerable quantity of water in the form of sap and moisture. If this precaution is not taken, there are chances for timber to become warped or cracked. Besides being blogger, she also participates in quantity survey, site management, design & detailing. Water seasoning is done to reduce the sap . 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 Reasons for Timber Seasoning Freshly felled timber contains moisture 100 to 200% of its dry weight. Unsupported ends of boards placed on the inside of the pile will dry with fewer defects than if allowed to extend over the end of the pile. Artificial seasoning is the process by which lumber is dried using man-made devices such as a kiln. It may be further classified into the following: a. Timber for building construction is available from different species of plants. Removal of moisture from timber so as to be in equilibrium with the moisture in surrounding atmospheric condition, where timber is likely to be used is called the seasoning of timber. 2) Kiln Seasoning Advantages: Insects are killed during this process, Require little stacking space, Moisture content of the timber may be brought to any desired level It depends on the temperature of the air injected into the chamber where the timber is piled and on the rate at which the air is circulated and extracted from the chamber. Felling, Preparation of Natural Wood and Seasoning. Care is taken to see that there is proper air circulation around each timber balk. A. It takes more than six months for timber to season in moderate climates. Sal wood and laurel wood. Natural Seasoning has two methods (I) Water Method (II) Air Method. (iii) Due to attack by fungi and insects. In natural seasoning, timber is dried by natural elements like air and water. It requires skilled labour. By natural process, the timber is seasoned. Air can then circulate around and through the stack, to slowly remove moisture. Stacked stable and safely with horizontal spacing of at least 25 mm. Water Seasoning This is the natural method of seasoning in which the timber is immersed in water to remove the sap of timber. It should be noted that all the types of timber either naturally durable or non-durable, need proper seasoning to give satisfactory service. The 25 mm thick timber may take three to four months to dry in a moderate climate. From childhood days ­ Ends of boards sealed by using a suitable sealer or cover to prevent too rapid drying out via the end grain. To give strength, hardness and to make electrically resistant. Copyright 2020 GharPedia. When timber is felled, the sooner it is removed from the forest the better; it should be removed to a dry situation, and placed so that the air may circulate freely around each piece, but it should not be exposed to the sun and wind. In this method timber immersed in water flow to remove the sap from timber. Natural Seasoning : Timber pieces can either be stacked horizontally or vertically and the seasoning is carved out by natural air. Types of these defects in wood are discussed in detail. 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). The . Timber seasoning reduces the risk of fungal attack. Double Flight Staircase!!! a) Kiln seasoning:- In this process timber is seasoned under controlled temperature and humidity condition with proper air circulation and ventilation system. Seasoning of Timber Revised by A. LAMOND and J. HARTLEY "Free" and "Bound" moisture Expressed as a formula: Fibre saturation point As the free moisture leaves the cell cavity, it will eventually become empty, leaving the cell wall still saturated. This system of piling is called "box piling" and has proven to be the best method of piling random length lumber. comes from the . In humid areas this may be necessary if a dry kiln is not available. Generally, air seasoning is a slow process. The timber is piled in such a way so that there is good air circulation between the wood. Twitter, Instagram, Pinterest 2 feet above the other the open and! 10 – 20 % ) Fresh cut, it is used, the electrodes are kept in contact ``! 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