PRESERVATION OF Marine wood

PRESERVATION OF Marine wood : 

PRESERVATION OF Marine wood N.KANAGARAJ BSF-06-007 BSC[FORESTRY]

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Marine timbers are used for jetties, piles, catamarans, harbour works, decks and cabins of ships, coastal and fishing vessels and also for small boats. There is immense damage to timber by Decay Fungal attack Insects, mainly marine borers Fire (in exposed situations) Marine wood

Marine wood : 

Marine wood Submerged portions of pilings, wharf timbers, and wooden boats in brackish or salt water are damaged extensively by a group of animals known collectively as “marine borers.” Untreated timbers can be infested and destroyed by these organisms in less than a year.

Marine Wood Borers : 

Marine Wood Borers Major marine borers in the Northwest include species in the phylla Mollusca - “shipworms” Crustacea - “gribbles Shipworms drill tunnels in wood and line them with a thin, shell-like substance. The giant shipworm -Bankia setacea Teredo sp (Teredo navalis).

Gribbles (Limnoria spp.) : 

Gribbles (Limnoria spp.) Gribbles (Limnoria spp.) mine the outer part of pilings and other marine structures. Attack takes place from the mud line to the upper tidal level. Their attack is mostly internal, making detection difficult Gribbles are common in habitats all along the West Coast.

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The griddle (limnoria lignorium) Is a common crustacean and can be found in most wooden pier and harbor piles which have stood for any length of time in the sea. Three species of the isopod genus limnoria are found to damage marine wood.

Limnoria tignorium : 

Limnoria tignorium l. tignorium a small organism about 3mm long and usually present in large number They bore into the wood with help of mandibles which bordered in the mouth

Damage : 

Damage A serious of galleries are formed on the surface of the wood which are eventually carried away by wave and current action. They mainly bore on the wood for protection it feed on the algae and fungi on the surface of the wood.

Ship worm (Teredo navalis) : 

Ship worm (Teredo navalis) Which is larger than griddle growing upto 45 cm long The body is long and worm like with sheels confined to the tip. It live in the burrows of the wood and feed on it.

Nacerdes melanura : 

Nacerdes melanura Found in water water logged wood . It is commonly found in old buildings or river wharf pilling in fresh or brackish water. The large tunnel in the wood and the adult beetle emerges above the water line. Historic boat timbers have been seriously damaged by it.

Control of marine borers : 

Control of marine borers Metal sheathing of wood have used in the past , a technique which also has application in prevention of marine algae and barnacle fouling (“copper bottomed”). The main drawback with regard to marine borers is that the sheathing needs to be perfect and continous with no holes or gaps.

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preservative solutions or their combinations used: a) Copper-Chrome-Arsenic composition b) Acid-Cupric-Chrome composition c) Pentachlorophenol d) Copper-Chrome-Boric composition e) Chromated zinc chloride f) Copper napthenate/resinate g) Boric acid: borax When the timber is to be used in exposed situations, fire retardants are also used in the preservative composition.

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Creosote is an oily liquid produced when coal is heated in the absence of air. This material usually is used as a preservative for marine pillars and fencing in water logged areas.

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Inorganic arsenicals consist of combinations of copper and arsenic. The most commonly used compounds are chromated copper arsenate (CCA) and ammoniacal copper zinc arsenate. These preservatives are water-soluble but, when applied to wood, they become fixed in the wood in an insoluble form.

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The copper protect against fungi The arsenic prevents insect attack. These preservatives no longer are used for residential applications, but can be used for farm, highway, and marine applications.

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Copper chrome aresenate (cca) compounds applied initially by pressure impregnation . Leaching of wood is a problem in the marine environment and re imprignation may be difficult or impossible . Even the use explosives has been suggested to kill the organism by shock waves. The force needed to achieve this is so great that the structure itself would inevitably sustain damage.

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SeaFin Teak Oil High quality, penetrating oil that dries well. Protect interior and exterior woods from moisture and weathering. It creates a durable non-slip surface to repel water and resist wear. AquaSpar, gloss and satin Waterborne polyurethane spar varnish, designed for marine applications. Offers excellent protection from sun, salt air and water.

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SeaFin Sealer-Filler-Stain It seals, fills the wood's pores, and stains the wood in your choice of three traditional marine colors. It gives marine wood a smooth, even finish