Tyrian purple 520 nm, which is green). It is believed that the intensity of the purple hue improved rather than faded as the dyed cloth aged. Vitruvius mentions the production of Tyrian purple from shellfish. In his "History of Animals", Aristotle described the shellfish from which Tyrian purple was obtained and the process of extracting the tissue that produced the dye. Pliny the Elder described the production of Tyrian purple in his "Natural History": The most favourable season for taking these [shellfish] is after the rising of the Dog-star, or else before spring; for when they have once discharged their waxy secretion,
Dye destruction archival qualities. Older dye destruction processes included Utocolor (early 1900s) and Gasparcolor (1930s). Dye destruction Dye destruction or dye bleach is a photographic printing process, in which dyes embedded in the paper are bleached (destroyed) in processing. Because the dyes are fully formed in the paper prior to processing, they may be formulated with few constraints, compared with the complex dye couplers that must react in chromogenic processing. This has allowed the use of richly colored, highly stable dyes. It is a reversal process, meaning that it is used in printing transparencies (diapositives). Ilfochrome (originally Cibachrome) is currently the only