Conservation bleaching

Burgess, H. D. The Degradation of Cellulose in Conservation Bleaching Treatments M.A.C. Thesis, Art Conservation Programme, Queen s Univ., Kingston, Canada, 1979. 

H. Burgess, Practical considerations for conservation bleaching, J. Int. Inst. 

Carter, Hemy A. (1996). The Chemistrjr of Paper Preservation. Part 2 The Yellowing of Paper and Conservation Bleaching. yowrwa/ of Chemical Education 73(11) 1,068-1,073. 

Inhibition of cytochromes of electron transport system can be caused by cyanogenic glycosides, such as amygdalin (Fig. 11.14) in bitter almonds, Prunus amygdalus, linamarin and lotaustralin in clover and birdsfoot trefoil, or dhurrin (Fig. 11.14) in Sorghum vulgare. The potent effect of cyanide on cell respiration has given rise to a recent serious conservation problem. In Southeast Asia, divers stun fish on coral reefs with a blast of cyanide to collect them for the aquarium trade. In the process, many fish are killed and the corals bleached, because their symbionts die (e.g. Payne, 2001). 

Oanh, N.T.K. (1996) A comparative study of effluent toxicity for three chlorine-bleached pulp and paper mills in Southeast Asia, Resources, Conservation and Recycling 18 (1-4), 87-105. 

Natural fibers may be adversely affected by sunlight, air pollutants, acids and alkali, bleaches and other oxidizing agents, and chemical finishing processes. However, the effects of photochemical degradation are by far the most problematic in the conservation of textiles and therefore have received the most attention. 

Conservators work in an interesting field of art and science interwoven, repairing the havoc created in artifacts by time, by molds, by insects, by polluted atmospheres, and by people. Some of their most difficult problems are those that were created by conservators of earlier times who used irreversible techniques, overly strong adhesives, and aggressive bleaches. 

On the other hand, there are many operations in conservation, used by conservators, that have been studied by chemists for years, such as bleaching, washing, and adhering. The correct procedures should be presented to conservators in relatively nontechnical language. There is a need for a text written along these lines. 

Brightness reversion is one of the serious problems for paper industries, restorers, paper conservators, and librarians, because the brightness of neither unbleached nor bleached pulp is permanent, and the causes and prevention of reversion still are not known entirely. 

Some useful practical inferences can be drawn from this work for the conservation treatment of bleached kraft paper. 

Only very recently, however, has tetrahydridoborate reduction been considered to be more than just a bleaching method in the conservation of cellulosic textiles and paper. To some extent, the delay in studying the... 

Burgess, H. D. The Color Reversion of Paper After Bleaching , Preprints The Conservation of Library and Archive Materials and the Graphic Arts Cambridge, 1980 Conference, 171, (1980). 

What direct effects climate change will have on various aspects of nitrogen cycling on reefs including coral bleaching events and zooxantheUae expulsion, remains to be seen. The subsequent consequences for nitrogen conservation and nitrogen acquisition of the corals and other symbioses, on the reef will undoubtedly be affected as the balance between symbionts and host interaction is very sensitive to environmental conditions (Knowlton, 2001). 

In a conservative estimate, 50% reduction in bleaching clay use (55,445 tons) and disposal is obtained. 

Many of the bleaching processes are derived from the paper industry as paper pulps often need to be bleached before being formed into paper products. Much more research has been carried out on bleaching than has ever been done by conservation scientists and the paper science literature is a good place for any paper conservation scientist wanting more information. 

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