Spot test or preservative test

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Slide 1: 

PRESENTED BY N.KANAGARAJ BSF-06-007 BSC[FORESTRY]

PRESENTATION TOPIC : 

Spot test or preservative test PRESENTATION TOPIC

Introduction : 

Introduction Penetrability is the important property. If the preservative is not deeply penetrated it will not protect the timber for long time as cracks and checks developed during to weathering It make entrance routes for the insects or fungi spores and start decay of untreated portion .

Cont….. : 

Cont….. The penetrability is determined by the color change or by spot test on the cross section of samples by cutting the sample in the middle or by taking increment boring of the treated blocks

spot tests : 

spot tests CREOSOTE: Creosote and its mixture with fuel oil impart a dark brown color to the treated timber . Excess moisture in wood is likely to produce sludge or emulsified creosote ,which retards the penetration .

CONT…. : 

CONT…. The penetration can be judged by taking a core with an increment borer or by cutting the wood substance . The quality of creosote and its conformity to IS: 218 -1961 has to be checked in a lab

Slide 7: 

The depth of penetration of pcp can be judged by simple spot test .quantitative estimation is possible only in a lab (i)Penta –check using a silver copper complex This method is recommended for determining the penetration of PCP in treated wood (ii)4-4 Bis –dimethylamine triphenylmethane test PENTACHLOROPHENOL

TIN IN TRIBUTYL TIN OXIDE: : 

TIN IN TRIBUTYL TIN OXIDE: This is more recent organic solvent based wood preservative used for treatment of building timbers .not till introduced in India,so far Bromo pyrogallol red method Catechol violet method

TRIBUTYL TIN OXIDE: : 

TRIBUTYL TIN OXIDE:

BROMO PYRAGALLOL RED METHOD : 

BROMO PYRAGALLOL RED METHOD Spray sol of 0.2 g treated of bromopyrogallol red dissolved in 100ml methanol on timber .Treated portions develop a blue color while untreated portions are colored red. exposure to U.V rays improves the sensitivity

Catechol violet method : 

Catechol violet method Spray the reagent on treated wood surface which has previously been exposed to u.v light for 20 minutes .treated areas will develop a blue color

PENETRATION GRAPH OF WOOD : 

PENETRATION GRAPH OF WOOD

ZINC IN ORGANIC SOLVENT PRESERVATIVES : 

ZINC IN ORGANIC SOLVENT PRESERVATIVES Such as zinc napthanates. Dithiozone solution is sprayed directly on to surface of wood. Areas penetrated with zinc will develop a pink color

Water soluble preservatives : 

Water soluble preservatives Copper (I)chrome azurol S method (2)Rubeanic acid method

(I)chrome azurol S method : 

(I)chrome azurol S method Dissolve 0.5 g chrome azurol s and 5 g of sodium acetate in 100 ml of water .Spray the timber or core with a fine spray of the above mixture avoiding too much spray .Untreated portions remain red where treated portions change in to red

(2)Rubeanic acid method : 

(2)Rubeanic acid method 0.5 g rubeanic acid in 100 ml of ethanol .dissolve 5g sodium acetate in 100 ml of water .spray successively the treated timber or core with above solutions .copper containing portions will develop dark green color while untreated portions will turn pale yellow Although both the above methods are equally sensitive

CHROMIUM : 

CHROMIUM Dissolve 0.5 g s – diphenyl carbazide in 50 ml of isopropyl alcohol and 50 ml of distilled water. Spray the above solution on treated wood .Portions containing chromium will develop a purple color . Un penetrated remains as such

ARSENIC : 

ARSENIC Hydrazine method .dissolve o.15 g hydrazine in 100 ml water and 1g ammonium molybdate in 100 ml sulphuric acid Mix 10 ml of ammonium molybdate solution with 100 ml of hydrazine solution and add a few wood shaving. heat the solution for about 10 minutes at 50º c. blue color indication presence of arsenic

BORON : 

BORON Dissolve 0.2 g of turmeric powder in 10 ml 0f 95% alcohol .prepare a saturated solution of salicylic acid in 10 ml of 6% HCL . Spray alcoholic extract of turmeric on the wood surface .allow the surface to dry a bit and apply salicylic acid extract .the treated surface will develop a red color within a few minutes

FLOURIDE : 

FLOURIDE Dissolve 1g zirconyl chloride in 100 ml water . Dissolve 2g of sodium alizarin sulphonate in 40 ml concentrated HCL & dilute to 500 ml Add 10 ml of sodium alizarin sulphonate to 10 ml of zirconyl chloride solution Spray the treated wood with mixture. Areas containing flouride will be colored bright yellow ,untreated portion remains red

ZINC : 

ZINC Stock solutions of the following chemicals should be prepared Potassium ferrocyanide Potassium iodide Soluble starch

CONT…. : 

CONT…. Mix 10 ml of each of the above 3 solutions and spray on surface of wood Portion containing zinc will change instantaneously

RETENTION REQUIREMENTS FOR DIFFERENT END USES : 

RETENTION REQUIREMENTS FOR DIFFERENT END USES The retention of preservative chemicals in timber member depends upon the condition of its use as it is subjected to different hazards of deterioration If the member is used in the open and exposed to weather ,higher retention are required

Slide 24: 

For Indoor Conditions ,Where There Is No Fear Of Leaching And Direct Sunlight ,Lower Retentions Can Be Used Effectively. On the basis the recommended practice with regard to choice of preservative ,treatment process retention and penetration to be adopted

References : 

References Wood preservation in India – Sathish Kumar & Indra Dev Www. wikipedia . Com

THANK U FOR UR ESTEEMED PRESENCE ………. : 

THANK U FOR UR ESTEEMED PRESENCE ……….

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