"Indian rosewood" redirects here. Indian rosewood may also refer to Dalbergia latifolia.
Dalbergia sissoo (or Indian Rosewood) is a deciduous rosewood tree, also known as shisham/ ,شیشمsisu, sheesham, tahli/Tali/ ,ٹالیor Irugudujava. It is native to the Indian Subcontinent and Southern Iran. In Persian, it is called جگJag. It is the state tree of Punjab state (India) and the provincial tree of Punjab province (Pakistan). It is primarily found growing along river banks below 900 metres (3,000 ft) elevation, but can range naturally up to 1,300 m (4,300 ft). The temperature in its native range averages 10–40 °C (50–104 °F), but varies from just below freezing to nearly 50 °C (122 °F). It can withstand average annual rainfall up to 2,000 millimetres (79 in) and droughts of 3–4 months. Soils range from pure sand and gravel to rich alluvium of river banks; shisham can grow in slightly saline soils. Seedlings are intolerant of shade.
Sheesham wood Shisham is best known internationally as a premier timber species of the rosewood genus, but is also used as fuel wood and for shade and shelter. With its multiple products and tolerance of light frosts and long dry seasons, this species deserves greater consideration for tree farming, reforestation and agro forestry applications. After teak, it is the most important cultivated timber tree of the Bihar, which is the largest producer of shisham timber in India and Pakistan. In the Bihar, the tree is planted on roadsides, along canals and as a shade tree for tea plantations. It is also commonly planted in southern Indian cities like Bangalore as a street tree.
Shisham is among the finest cabinet and veneer timbers. It is the wood from which 'Kartaals', the Rajasthani percussion instrument, are often made. In addition to musical instruments, it is used for plywood, agricultural tools, carvings, boats, skis, flooring, etc. The heartwood is golden to dark brown; the sapwood, white to pale brownish white. The heartwood is extremely durable (the specific gravity is 0.7 – 0.8) and is very resistant to dry-wood termites; but the sapwood is readily attacked by fungi and borers. Dalbergia sissoo is known to contain the neoflavonoid dalbergichromene in its stem-bark and heartwood[1].
Fuel wood
The calorific value of the sapwood and heartwood of 'excellent' fuel wood is reported to be 4,908 kcal/kg and 5,181 kcal/kg respectively. As a fuel wood it is grown on a 10 to 15-year rotation. The tree has excellent coppicing ability, although a loss of vigor after two or three rotations has been reported. Shisham wood makes excellent charcoal for heating and cooking.
Botany
D. sissoo is a medium to large deciduous tree with a light crown which reproduces by seeds and suckers. It can grow up to a maximum of 25 m (82 ft) in height and 2 to 3 m (6 ft 7 in to 9 ft 10 in) in diameter, but is usually smaller. Trunks are often crooked when grown in the open. Leaves are leathery, alternate, pinnately compound and about 15 cm (5.9 in) long. Flowers are whitish to pink, fragrant, nearly sessile, up to 1.5 cm (0.59 in) long and in dense clusters 5–10 cm (2.0–3.9 in) in length. Pods are oblong, flat, thin, strap-like 4–8 cm (1.6–3.1 in) long, 1 cm (0.39 in) wide and light brown. They contain 1–5 flat bean-shaped seeds 8–10 mm (0.31–0.39 in) long. They have a long taproot and numerous surface roots which produce suckers. Young shoots are downy and drooping; established stems with light brown to dark gray bark to 2.5 cm (0.98 in) thick, shed in narrow strips; large upper branches support a spreading crown.
Propagation
Propagation takes place most commonly by root suckers and also by seeds. The seeds remain viable for only a few months. Seeds should be soaked in water for 48 hours before sowing and 60% – 80% germination can be expected in 1–3 weeks. Seedlings require partial sun or full sun.
Toxicology
Ethanolic extract of the fruits of Dalbergia sissoo exhibited molluscicide effect against eggs of the freshwater snail Biomphalaria pfeifferi.[2]
References
1. ^ S. K. Mukerjee, T. Saroja & T. R. Seshadri (1971). "Dalbergichromene : a new neoflavonoid from stem-bark and heartwood of Dalbergia sissoo". Tetrahedron 27 (4): 799–803. doi:10.1016/S0040-4020(01)92474-3. 2. ^ Adenusi A. A. & Odaibo A. B. (2009). "Effects of varying concentrations of the crude aqueous and ethanolic". African Journal of Traditional, Complementary and Alternative medicines 6(2). abstract, PDF.
Sheesham (also known as Indian Rosewood) is a fast-growing hardwood, sourced from sustainable, government managed plantations. Being a hard wood, it can be used to make functional furniture that copes with the stresses and sPlywood
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Softwood plywood made from spruce Plywood is a manufactured wood panel made from thin sheets of wood veneer. It is one of the most widely used wood products. It is flexible, inexpensive, workable, re-usable, and can usually be locally manufactured. Plywood is used instead of plain wood because of its resistance to cracking, shrinkage, splitting, and twisting/warping, and its general high degree of strength. Plywood layers (called veneers) are glued together with adjacent plies having their grain at right angles to each other. Cross-graining has several important benefits: it reduces the tendency of wood to split when nailed at the edges, it reduces expansion and shrinkage equating to improved dimensional stability, and it makes the strength of the panel consistent across both directions. There are usually an odd number of plies so that the sheet is balanced—this reduces warping. Because of the way plywood is bonded (with grains running against one another and with an odd number of composite parts) it is very hard to bend it perpendicular to the grain direction.
Contents
• • •
• • • •
1 History 2 Structural characteristics 3 Types o 3.1 Softwood plywood o 3.2 Hardwood plywood 3.2.1 Tropical plywood o 3.3 Special-purpose plywood 3.3.1 Aircraft plywood 3.3.2 Decorative plywood (overlaid plywood) 3.3.3 Flexible plywood 3.3.4 Marine plywood 3.3.5 Other plywoods 4 Production 5 Sizes 6 Grades 7 Applications
• • •
7.1 Softwood plywood applications 7.2 Birch plywood applications 7.3 Tropical plywood applications 8 See also 9 References
o o o
10 External links
History
Plywood was invented around 3500 B.C. by the Egyptians, who attached several thinner layers of wood together to make one thick layer. They originally did this during a shortage of quality wood, gluing very thin layers of quality wood over lesser-quality wood.[citation
needed]
Modern plywood was invented by Immanuel Nobel, father of Alfred Nobel. Nobel realized that several thinner layers of wood bonded together would be stronger than one single thick layer of wood.
Structural characteristics
A typical plywood panel has face veneers of a higher grade than the core veneers. The principal function of the core layers is to increase the separation between the outer layers where the bending stresses are highest, thus increasing the panel's resistance to bending. As a result, thicker panels can span greater distances under the same loads. In bending, the maximum stress occurs in the outermost layers, one in tension, the other in compression. Bending stress decreases from the maximum at the face layers to nearly zero at the central layer. Shear stress is consistent throughout the depth of the panel.[citation needed]
Types
Average-quality plywood with 'show veneer'
High-quality concrete pouring plate in plywood
Birch plywood Different varieties of plywood exist for different applications:-
Softwood plywood
Softwood panel is usually made either of cedar, Douglas fir or spruce, pine, and fir (collectively known as spruce-pine-fir or SPF) or redwood and is typically used for construction and industrial purposes.[1] The most common dimension is 1.2 m × 2.4 m or the slightly larger imperial dimension of 4 feet × 8 feet. Plies vary in thickness from 1.4mm to 4.3mm. The amount of plies depends on the thickness and grade of the sheet but at least 3. Roofing can use the thinner 5/8" (15mm) plywood. Subfloors are at least 3/4" (18mm) thick, the thickness depending on the distance between floor joists. Plywood for flooring applications is often tongue and groove; This prevents one board from moving up or down relative to its neighbor, so providing a solid feeling floor when the joints do not lie over joists. T&G plywood is usually found in the 1/2" to 1" (12-21mm) range
Hardwood plywood
Used for demanding end uses. Birch plywood is characterized by its excellent strength, stiffness and resistance to creep. It has a high planar shear strength and impact resistance, which make it especially suitable for heavy-duty floor and wall structures. Oriented plywood construction has a high wheel-carrying capacity. Birch plywood has excellent surface hardness, and damage- and wear-resistance.[2]
Tropical plywood
Tropical plywood is always made of mixed species of tropical wood in the Asian region. Tropical plywood is superior to softwood plywood due to its density, strength, evenness of layers, and high quality. It is usually sold at a premium in many markets if manufactured with high standards. Tropical plywood is widely used in the UK, Japan, Taiwan, Korea, Dubai, and other countries worldwide. It is the most preferred choice for construction purposes in many regions.
Special-purpose plywood
Certain plywoods do not have alternating plies. These are designed for specific purposes.
Aircraft plywood
High-strength plywood, known as aircraft plywood, is made from mahogany and/or birch, and uses adhesives with increased resistance to heat and humidity. It was used for several World War II fighter aircraft, including the British-built Mosquito bomber, which was nicknamed "The Wooden Wonder". Structural aircraft-grade plywood is more commonly manufactured from African mahogany or American birch veneers that are bonded together in a hot press over hardwood cores of basswood or poplar. Basswood is another type of aviation-grade plywood that is lighter and more flexible than mahogany and birch plywood but has slightly less[citation needed] structural strength. All aviation-grade plywood is manufactured to specifications outlined in MIL-P-607, which calls for shear testing after immersion in boiling water for three hours to verify the adhesive qualities between the plies and meets specifications.
Decorative plywood (overlaid plywood)
Usually faced with hardwood, including ash, oak, red oak, birch, maple, mahogany, Philippine mahogany(often called lauan), rose wood, teak and a large number of other hardwoods. However, Formica, metal and resin-impregnated paper or fabric bonded are also added on top of plywood at both side as a kind of ready for use in the decoration field.
Flexible plywood
Flexible plywood is very flexible and is designed for making curved parts. In the UK this is sometimes known as "Hatters Ply" as it was used to make stovepipe hats in Victorian times[citation needed]. It is also often referred to as "Bendy Ply" due to its flexibility. However these may not be termed plywood in some countries because the basic description of plywood is layers of veneered wood laid on top of each other with the grain of each layer perpendicular to the grain of the next. In the US, the terms "Bender Board" and "Wiggle Board" are commonly used.
Marine plywood
Marine plywood is manufactured from durable face and core veneers, with few defects so it performs longer in humid and wet conditions and resists delaminating and fungal attack. Its construction is such that it can be used in environments where it is exposed to moisture for long periods. Each wood veneer will be from durable tropical hardwoods, have negligible core gap, limiting the chance of trapping water in the plywood and hence providing a solid and stable glue bond. It uses an exterior Water and Boil Proof (WBP) glue similar to most exterior plywoods. Marine plywood can be graded as being compliant with BS 1088, which is a British Standard for marine plywood. There are few international standards for grading marine plywood and most of the standards are voluntary. Some marine plywood has a Lloyd's of London stamp that certifies it to be BS 1088 compliant. Some plywood is also labeled based on the wood used to manufacture it. Examples of this are Okoume or Meranti Marine plywood is frequently used in the construction of docks and boats. It is much more expensive than standard plywood: the cost for a typical 4-foot by 8-foot 1/2-inch thick board is roughly $75 to $100 US or around $2.5 per square foot, which is about three times as expensive as standard plywood.
Other plywoods
Other types of plywoods include fire-retardant, moisture-resistant, sign-grade and pressuretreated. However, the plywood may be treated with various chemicals to improve the plywood's fireproofing. Each of these products is designed to fill a need in industry.
Production
Plywood production requires a good log, called a peeler, which is generally straighter and larger in diameter than one required for processing into dimensioned lumber by a sawmill. The log is laid horizontally and rotated about its long axis while a long blade is pressed into it, causing a thin layer of wood to peel off (much as a continuous sheet of paper from a roll). In this way the log is peeled into sheets of veneer which are then cut to the desired dimensions, dried, patched, glued together and then baked in a press at 140 °C (284 °F) and 1.9 MPa (280 psi) to form the plywood panel. The panel can then be patched, re-sized, sanded or otherwise refinished, depending on the market for which it is intended. Plywood for indoor use generally uses the less expensive urea-formaldehyde glue which has limited water resistance, while outdoor and marine-grade plywood are designed to withstand rot, and use a water resistant phenol-formaldehyde glue to prevent delamination and to retain strength in high humidity. The adhesives used in plywood have become a point of concern. Both urea formaldehyde and phenol formaldehyde are carcinogenic in very high concentrations. As a result, many
manufacturers are turning to low formaldehyde-emitting glue systems, denoted by an "E" rating ("E0" possessing the lowest formaldehyde emissions). Plywood produced to "E0" has effectively zero formaldehyde emissions.[3] In addition to the glues being brought to the forefront, the wood resources themselves are becoming the focus of manufacturers, due in part to energy conservation, as well as concern for natural resources. There are several certifications available to manufacturers who participate in these programs. Forest Stewardship Council (FSC), Leadership in Energy and Environmental Design (LEED), Sustainable Forestry Initiative (SFI), and Greenguard are all certification programs that ensure that production and construction practices are sustainable. Many of these programs offer tax benefits to both the manufacturer and the end user.[4]
Sizes
The most commonly used thickness range is from 0.14 to 3.0 in (0.36 to 7.6 cm). The sizes of the most commonly used plywood sheets are 4 by 8 ft (1.2 by 2.4 m) or 3 by 6 ft (0.91 by 1.8 m). Width and length may vary in 1 ft (30 cm) increments. In the United States, the most commonly used size is: 4 ft by 8 ft or 5 ft by 5 ft.[5] Sizes on specialised plywood for concrete forming range from 6 to 21mm, and a multitude of formats exist, though 15x750x1500mm is very commonly used.
Grades
Grading rules differ according to the country of origin. Most popular standard is the British Standard (BS) and American Standard (ASTM). Joyce (1970), however, list some general indication of grading rules:[6] Grade Description A Face and back veneers practically free from all defects. Face veneers practically free from all defects. Reverse veneers with only a few A/B small knots or discolorations. A/BB Face as A but reverse side permitting jointed veneers, large knots, plugs, etc. B Both side veneers with only a few small knots or discolorations. Face veneers with only a few small knots or discolorations. Reverse side permitting B/BB jointed veneers, large knots, plugs, etc. BB Both sides permitting jointed veneers, large knots, plugs, etc. WG Guaranteed well glued only. All broken knots plugged. X Knots, knotholes, cracks, and all other defects permitted. JPIC Standards
Description Face as BB, back as CC. BB as very little knots of less than 1/4 inches, slight BB/CC discoloration, no decay, split and wormholes mended skillfully, matched colors, no blister, no wrinkle. Most popular choice for most applications.
Grade
Applications
Plywood is used in many applications that need high-quality, high-strength sheet material. Quality in this context means resistance to cracking, breaking, shrinkage, twisting and warping. Exterior glued plywood is suitable for outdoor use, but because moisture affects the strength of wood, optimal performance is achieved in end uses where the wood's moisture content remains relatively low. On the other hand, subzero conditions don't affect plywood's dimensional or strength properties, which makes some special applications possible. Plywood is also used as an engineering material for stressed-skin applications. It has been used for marine and aviation applications since WWII. Most notable is the British de Havilland Mosquito bomber, which was primarily made using a moulded sandwich of two layers of birch plywood around a balsa core. Plywood is currently successfully used in stressed-skin applications.[citation needed]. The American designers Charles and Ray Eames are famous for their plywood-based furniture, while Phil Bolger is famous for designing a wide range of boats built primarily of plywood. Plywood is often used to create curved surfaces because it can easily bend with the grain. Skateboard ramps often utilize plywood as the top smooth surface over bent curves to create transition that can simulate the shapes of ocean waves.
Softwood plywood applications
Typical end uses of spruce plywood are:
• • • • •
Floors, walls and roofs in house constructions Wind bracing panels Vehicle internal body work Packages and boxes Fencing
There are coating solutions available that mask the prominent grain structure of spruce plywood. For these coated plywoods there are some end uses where reasonable strength is needed but the lightness of spruce is a benefit e.g.:
• •
Concrete shuttering panels Ready-to-paint surfaces for constructions
Birch plywood applications
Phenolic-film Coated birch plywood is typically used as a ready-to-install component e.g.:
• • • • •
Panels in concrete form work systems Floors, walls and roofs in transport vehicles Container floors, Floors subjected to heavy wear in various buildings and factories, Scaffolding materials ("Wire" or other styles of imprinting available for better traction)
Birch plywood is used as a structural material in special applications e.g.:
• •
Wind turbine blades Insulation boxes for Liquefied Natural Gas (LNG) carriers
Smooth surface and accurate thickness combined with the durability of the material makes birch plywood a favorable material for many special end uses e.g.:
• • • • • • • •
High-end loud speakers Die-cutting boards Supporting structure for parquet Playground equipment Furniture Signs and fences for demanding outdoor advertising Musical instruments Sports equipment
Tropical plywood applications
Tropical plywood is widely available from the South-East Asia region, mainly from Malaysia and Indonesia. Tropical plywood boasts premium quality, and strength. Depending on machinery, tropical plywood can be made with high accuracy in thickness, and is a highly preferable choice in America, Japan, Middle East, Korea, and other regions around the world.
• • • • • • •
Common plywood Concrete panel Floor base Structure panel Container flooring Lamin board Laminated Veneer Lumber (LVL)
trains of everyda Plywood is a versatile building material that can be used in decks, flooring, roofing and walls. Plywood is used in many interior and exterior applications and is even found in boat construction. It is durable material that provides a excellent foundation for building. Advantages Plywood is constructed of layers of wood glued together at right angles, which is what gives it its strength. This layering make the plants resistant to warping, cracking and twisting, making it ideal for use in construction. In addition to its strength, plywood is less expensive than similar boards made of full wood species, which makes it ideal as a construction planking material. Disadvantages The layering effect in plywood makes it porous and susceptible to water damage if exposed over time. Plywood becomes heavy when wet and should be covered if left outside to reduce the risk of water damage. 1. 2. 3. 4. 5. eHow Home Building & Remodeling Wood Building Materials Plywood Advantages of Plywood
Advantages of Plywood
By Andrew Dewitt, eHow Contributor
Advantages of Plywood Plywood has become an integral part of construction today. From its creation in the early 20th century, plywood has undergone a great deal of transformation and refinement over the years. It started as a curiosity that has since become a stable product in all forms of construction. There are many advantages that plywood has over more traditional lumber. This article will give you a detailed account of the history, types, functions and advantages of plywood a lumber construction product. Does this Spark an idea?
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History
o
Plywood was first introduced in the market in the early 20th century. However, there is some evidence to suggest that ancient Egyptians and Romans created early versions of plywood with glue made from animal products. In modern history, however, the origins of plywood as a commercial product go back to the turn of the century in Portland, Oregon. Portland had a vibrant logging community and all the necessary components to create plywood on a mass scale. A man known as the pioneer of modern plywood, Thomas J. Autzen, created a process of gluing thinly sliced wood products together in such a way that they could be cheaply made and still retain strength. Over time. glues involving animal products were phased out, and stronger synthetic glues began to be used. Advances in technology allowed plywood boards to be fused under higher amounts of pressure, which prevents layers from flaking off or splitting. Today, plywood is used in almost every construction job on the planet.
Function
o
Plywood was designed to compensate for some of the inherit weaknesses in wood products. Each layer of plywood is laid with the grain turned in such a way that it reinforces the weak spots of the other layer. This creates a wood panel that is incredibly strong and durable. Another advantage of plywood is that it is cheap to make. Because plywood doesn't rely on coming from a single piece of wood, the materials are much easier to gather. Less time and money must be spent on harvesting a single usable sheet of wood from a tree. Because of this, plywood can be created and sold for less money with significantly less wasted wood.
o
There are several types of plywood. The most common are referred to as interior, exterior, structural and marine. It follows that interior plywood is for interior construction and is made of a quality that is acceptable for the inside of a home or office. Exterior is for using on the outside of a structure.
Structural is created in such a way that its strength allows it to be used to support massive amounts of weight. Marine plywood is plywood that has been waterproofed and can be used for building boats. Each of these types of plywood also has a grade quality ranging from A to D with A being the highest quality with the fewest imperfections and D being the lowest with many knots and splits being acceptable.
Benefits
o
One of the most touted benefits of plywood is in its incredible ease of use. Plywood can be cut and shaped with basic tools and very little experience. Because of the composition of plywood, shapes can be cut and started on any section of plywood. This allows an amateur builder to cut panels on an as-needed basis. Plywood can also be reshaped and bent into shapes that are not flat with relative ease. Compared to other wood products, plywood can change and retain shape very easily and can be done so without the threat of splitting or warping. This allows builders to create rounded walls with plywood that would not be possible with regular lumber.
Size
o
The vast majority of plywood comes in 4-foot-by-8-foot sheets. Because of its robust nature, plywood can be cut to size or nailed together side by side on a frame. Commercially it is usually available only in this particular size, though certain lumber companies will create custom-sized plywood panels at an additional cost to the consumer.
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Advantages of Plywood
1. High uniform strength - wood is 25-45 times stronger along the grain than across the grain. Crossing the adjacent sheets tends to equalise the strength in all directions. 2. Freedom from shrinking, swelling and warping - Solid wood exhibits considerable movement across the grain but generally negligible shrinkage or swelling in a longitudinal plane. The balanced construction of a plywood panel with the grain direction of adjacent veneers at right angles tends to equalise stress, thus reducing shrinkage, swelling and warping. 3. Non-splitting qualities solid wood splits fairly readily along the grain. Plywood by virtue of the crossed laminations can be nailed or screwed near the edges without damage from splitting. 4. Availability of relatively large sizes - Sawn timber can be obtained in fairly long lengths but only in relatively narrow widths. Plywood can be sold in sizes up to 6 ft * 25 ft and by the scarf jointing of small sheets up to 6 ft *40 ft, however 6 ft*3 ft is the most common size. 5. Economical and effective utilisation of figured wood - Twenty sheets of veneer can be sliced from 1 inch of solid wood, when glued to a core of cheaper material a high grade panel is produced. This procedure thus effects distinct economies in the use of figured or the more valuable woods. In addition to facilitating the utilisation of attractive but fragile face veneers to give results which cannot be duplicated in solid construction. More effective utilisation is obtained by the matching of veneer in such a manner that the decorative effect due to the natural figure in the wood is enhanced by the regularity or symmetry of the design. 6. Dense woods can be sliced and bonded into plywood panels for use in furniture construction whereas furniture fabricated from solid timer would be far to heavy. 7. Ease of fabrication of curved surfaces - The trend of modern architectural design is to feature curved surfaces. The desired shapes can be readily fabricated in plywood construction, utilising male and female forms, or a single forming a vacuum press or autoclave 8. One of the important aspects in the manufacture of plywood is that it results in the conservation of timber by the elimination of the waste which occurs in sawing eg sawdust. Waste is confined to the small core which remain after peeling, and from the veneer which is lost in rounding up the log, and the elimination of such defects a knots and splits.