English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The paper describes the effects of light bleaching with metal halide lamps on selected chemical and mechanical properties of six different naturally aged 18th-21st century papers. Treatments included: pre-washing under ambient light, prolonged immersion in a dilute calcium hydroxide solution while kept in the dark, exposure to high-intensity light in dry condition, and immersion in a dilute calcium hydroxide solution while exposed to high-intensity light (light bleaching treatment). The effects of the treatments on the papers were evaluated by the Yellowness Index (YI), pH, tensile strength (0-span tensile test) and the degree of polymerization. All these measurements and tests were repeated after artificial thermal ageing to evaluate the treatment effects over the long term. Light bleaching proved effective in reducing the yellowing in the rag paper after treatment and after ageing, although some colour reversion was observed after ageing. Light bleaching treatment brightened the chemical woodpulp paper, but the effect was nullified after ageing due to a high degree of colour reversion. Light bleaching showed only limited brightening effects on woodpulp paper after treatment; woodpulp paper samples darkened more during ageing than the rag paper and chemical woodpulp paper. Immersion in the alkaline bath increased the pH of all papers tested in this study and exposure to light in dry condition turned out to be detrimental for the pH both after exposure and after ageing. Exposure to light in dry condition and aqueous light bleaching both caused a decrease in the tensile strength of paper samples in the short-term. Light bleaching treatment caused a decrease in the degree of polymerisation of cellulose after treatment and after ageing.

Light Bleaching with Metal Halide Lamps: Effects on Naturally Aged Paper