Copper chrome arsenate

The best protection for wood against the attack of decay fungi, insects, or marine borers is obtained by applying preservatives under pressure before installation (61,62). Both oil-type preservatives, such as creosote or petroleum solutions of pentachlorophenol, and waterborne preservatives, such as copper-chrome arsenate and ammoniacal-copper arsenate, are used when wood is to be in direct contact with the ground or in the marine environments. 

Zinc in contact with wood Zinc is not generally affected by contact with seasoned wood, but oak and, more particularly, western red cedar can prove corrosive, and waters from these timbers should not drain onto zinc surfaces. Exudations from knots in unseasoned soft woods can also affect zinc while the timber is drying out. Care should be exercised when using zinc or galvanised steel in contact with preservative or fire-retardant-treated timber. Solvent-based preservatives are normally not corrosive to zinc but water-based preservatives, such as salt formulated copper-chrome-arsenic (CCA), can accelerate the rate of corrosion of zinc under moist conditions. Such preservatives are formulated from copper sulphate and sodium dichromate and when the copper chromium and arsenic are absorbed into the timber sodium sulphate remains free and under moist conditions provides an electrolyte for corrosion of the zinc. Flame retardants are frequently based on halogens which are hygroscopic and can be aggressive to zinc (see also Section 18.10). 

Dobbs, A.J. and Grant, C. (1978). The volatilisation of arsenic on burning copper-chrome-arsenic (CCA) treated wood. Holzforschung, 32(1), 32-35. 

Chou C.K, Chandler J.A. and Preston R.D, (1973) Microdistribution of metal elements in wood impregnated with a copper-chrome-arsenic preservative as determined by analytical electron microscopy. Wood Sci. Technol., 7, 151-160. 

Pines such as P. radiata are permeable and ean be dried quiekly (Table 8.4a). However their pits aspirate and if subsequently pressure impregnated with an aqueous preservative such as copper-chrome-arsenate using the full eell proeess they eannot be redried nearly as rapidly. If sueh resaturated, preservative treated timber were to be dried using the schedule in Table 8.4a steep moisture gradients would develop leading to severe checking. A milder schedule is required. Treated pine takes approximately twiee as long to dry. 

Bacterial attack has been observed in wood exposed in soil. The studies have mainly concerned posts treated with copper-chrome-arsenic preservatives. The reports show that erosion, tunneling, and cavitation forms of bacterial attack may occur 91, 92, 109-112). Extensive attack by bacteria in preservative-treated water-cooling slats was also reported by Greaves (100). 

CCO copper chrome arsenate GFRTP continuous fiber reinforced thermoplas-... 

CCA. See Copper chrome arsenate Chromate copper arsenate... 

Chromated copper arsenate. See Copper chrome arsenate Chromate copper arsenate Chromate(1 -), [3-[(4,5-dihydro-3-methyl-5-oxo-1 -phenyl-1 H-pyrazol-4-yl) azo]-2-hydroxy-5-nitrobenzenesulfonato (3-)] hydroxy-, sodium. See Acid orange 74... 

Calcium bromide Chromate copper arsenate Copper acetoarsenite Copper bromide (ic) Copper chrome arsenate... 

Copper chrome arsenate 37337-53-4 Fosamine ammonium 37340-08-2 Retinyl palmitate 37340-60-6 Rhodafac LO-529 Sodium nonoxynol-6 phosphate 37349-34-1 Calgene PGS-61 Calgene PGS-101 Calgene PGS-K Caprol 3GS... 

Anon. (1981). Corrosion of metal fasteners used in conjunction with CCA (copper/ chrome/arsenic) preservative treated timbers. Development Materials Bulletin, Greater London Council, December (135), 4/1-4/3. 

Chromium (VI) sulfate is used in the tamiing of leather. Chromic acid is used for the treatment of timber to produce copper chrome arsenic salts (CCAs). Potassium dichromate is used in the textile industry as a mordant... 

Greaves, 1972. Microbial ecology of untreated and copper-chrome-arsenic treated stakes exposed in tropical soil. I. The initial invaders. Can. J. Microbiol 18, 1923 1931. 

Durability of wood and wood-based products. Performance of preventive wood preservatives as determined by biological tests. Part 1. Specification according to hazard class Methods of analysis of wood preservatives and treated timber. Part 3. Quantitative analysis of preservatives and treated timber containing copper/chromium/arsenic formulations Specification for wood preservation by means of copper/chrome/arsenic compositions Standards for waterborne preservatives... 

---