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Chemical Modification Processes
Published in Dick Sandberg, Andreja Kutnar, Olov Karlsson, Dennis Jones, Wood Modification Technologies, 2021
Dick Sandberg, Andreja Kutnar, Olov Karlsson, Dennis Jones
Pitch and tar have been used since ancient times to increase the resistance of wood to water and decay. The need to develop durable sleepers and telephone poles during the industrial revolution led to treatment with the more potent creosote oil using pressurised autoclave techniques, patented by Moll in 1836 and by John Bethell in 1838 (Freeman et al., 2003). Apart from being hydrophobic, creosote oil has a strong biocidal effect and contains compounds that may be carcinogenic, but it is still used as a wood preservative in certain water and ground contact applications. Due to a greater awareness of the negative effect on human health and the environment of creosote oil and other preservatives like copper-chrome arsenic (CCA) and pentachlorophenol (PCP), there has been the search for more environmentally friendly materials, like vegetable oils and waxes.
Lighting
Published in Sue Reed, Dino Pisaniello, Geza Benke, Kerrie Burton, Principles of Occupational Health & Hygiene, 2020
In certain occupations, the risk from exposure to particular photosensitising chemicals and solar UV radiation is severe. For example, exposure to tar and sunlight can cause precancerous and cancerous skin lesions. Exposure to coal tar fumes can cause simultaneous inflammation of the conjunctiva and cornea. Ingestion or topical application of particular medications or prescribed drugs may cause photosensitivity in some individuals. Chemical-induced photosensitivity can occur in anybody, is usually dose related and may not happen on first exposure (ASCC 2008). Photosensitisation has been observed in workers exposed to creosote, which can induce phototoxic or photoallergic reactions, sometimes accompanied by general symptoms such as depression, weakness, headache, slight confusion, vertigo, nausea, increased salivation or vomiting. Exposure to creosote and sunlight may be linked to a significantly elevated risk of lip and skin cancer observed in cohort studies of Swedish and Norwegian wood impregnators and Finnish round timber workers. (Workplace Health and Safety, Queensland 2010). For a good account of photosensitisation, and a list of industrial chemicals, drugs, plants and miscellaneous other substances that are known to cause photosensitisation, the reader is referred to Appendix 2 of the ASCC (2008) publication Guidance Note for the Protection of Workers from the Ultraviolet Radiation in Sunlight.
Lighting
Published in Sue Reed, Dino Pisaniello, Geza Benke, Principles of Occupational Health & Hygiene, 2020
In certain occupations, the risk from exposure to particular photosensitising chemicals and solar UV radiation is severe. For example, exposure to tar and sunlight can cause pre-cancerous and cancerous skin lesions. Exposure to coal tar fumes can cause simultaneous inflammation of the conjunctiva and cornea. Ingestion or topical application of particular medications or prescribed drugs may cause photosensitivity in some individuals. Chemical-induced photosensitivity can occur in anybody, is usually dose related and may not happen on first exposure (ASCC, 2008). Photosensitisation has been observed in workers exposed to creosote, which can induce phototoxic or photoallergic reactions, sometimes accompanied by general symptoms such as depression, weakness, headache, slight confusion, vertigo, nausea, increased salivation or vomiting. Exposure to creosote and sunlight may be linked to a significantly elevated risk of lip and skin cancer observed in cohort studies of Swedish and Norwegian wood impregnators and Finnish round timber workers (WHO, 2004). For a good account of photosensitisation, and a list of industrial chemicals, drugs, plants and miscellaneous other substances that are known to cause photosensitisation, the reader is referred to Appendix 2 of the ASCC’s (2008)Guidance Note for the Protection of Workers from the Ultraviolet Radiation in Sunlight.
Structural health assessment techniques for in-service timber poles
Published in Structure and Infrastructure Engineering, 2023
Sahan Bandara, Pathmanathan Rajeev, Emad Gad
Once the decay depth is estimated, bending resistance of the pole at a given time, can be determined using bending theory: where is the bending strength of timber and is the initial diameter. This deterioration model is suitable for a homogeneous cross-section. However, timber poles cannot be assumed as homogeneous, and thus, this model was extended later to account for different decay rates in sapwood, heartwood, and core wood. Moreover, preservative treatment for timber poles such as CCA (Copper Chromium Arsenate) and creosote was considered for later developments of the initially proposed model
Morphine Dreams: Auguste Laurent and the Active Principles of Organised Matter
Published in Ambix, 2021
Laurent had first developed these ideas while working in the back of a perfume shop in Paris, and had not been able to experiment with the foul-smelling substances involved. But in Bordeaux, no one complained about the smell. So he pursued the spirit of coal tar as a bridge from his previous work isolating benzoic acid from the products of living plants to the subterranean world of fossil combustibles. He went further, using phenol to make picric acid, a substance that had traditionally come from the indigo plant, thus cementing the link between coal and plant products. He had acknowledged that phenol had properties very similar to both creosote and carbolic acid, a substance F. F. Runge (1794-1867) had gotten from coal tar in 1834, and speculated (correctly) that perhaps Runge’s carbolic acid was simply an impure form of phenol.33 He did a number of comparisons of the three substances (phenol, creosote, and carbolic acid), and while he found differences in boiling point and density, he noted the similarities of their taste and smell. He gave samples to several people who had toothaches (one of the traditional pharmacological uses of creosote), who reported that they all had the same effect, “strongly attacking the skin of the lips and the gums.”34
Bonnington chemical works (1822–1878): pioneer coal tar company
Published in The International Journal for the History of Engineering & Technology, 2020
Coal tar remained the more valuable of the gasworks residue streams. It was first distilled by fire and/or steam, depending on the coal mix used at the gasworks and the product properties desired. During cooling, the waste gases were now directed into a box of lime. The first oil fraction, after separating its accompanying water, was then in turn mixed with sulphuric acid in a lead trough to remove impurities, neutralised with quicklime, washed with water, and re-distilled, to be sold as rectified naphtha. The distilled tar was heated to a higher temperature in pitch stills to separate pitch oil, which Ronalds marketed successfully as ‘Creosote’.71 The residual pitch was now cooled in an apparatus that prevented the concomitant vapours from escaping, rather than the former approach of running it into an open tank. Although pitch was of use for fuel, the expense of transport meant that it in fact ‘lies in enormous heaps in many tar-works’.72 It could be distilled again ‘at a red heat’ to produce coke oil (which was combined with the pitch oil) and coke. Distilled tar, like pitch, had almost no current market – they were no longer in favour for protecting shipping infrastructure and sealing of roads was still in its infancy.73