Search results
Results from the WOW.Com Content Network
The table shows how the two systems rate high-brightness papers, but there is no simple way to convert between the two systems because the test methods are so different. [4] The ISO rating is higher and can be over 100. This is because contemporary white paper incorporates fluorescent whitening agents (FWA). Because the ISO standard only ...
Active oxygen bleaching agents include sodium perborate, sodium percarbonate, sodium perphosphate, sodium persulfate, and urea peroxide. These compounds release hydrogen peroxide during the wash cycle, but the release of hydrogen peroxide is low when these compounds are used in temperatures below 45 °C (113 °F).
Paper chemicals designate a group of chemicals that are used for paper manufacturing, or modify the properties of paper. These chemicals can be used to alter the paper in many ways, including changing its color and brightness, or by increasing its strength and resistance to water. [1] The chemicals can be defined on basis of their usage in the ...
The main objective of cleaning is to achieve clarity of surface detail. [57] Books and documents may be subjected to different types of cleaning. Conservators may clean dust from paper and leather with a soft brush or cloths, a specialized vacuum cleaner, nonchemical vulcanized rubber sponges, or nonabrasive erasing materials such as vinyl erasers.
Elemental chlorine free (ECF) is a technique that uses chlorine dioxide for the bleaching of wood pulp.It does not use elemental chlorine gas during the bleaching process and prevents the formation of dioxins and dioxin-like compounds, carcinogens.
Chlorine releasing solutions, such as liquid bleach and solutions of bleaching powder, can burn the skin and cause eye damage, [2] especially when used in concentrated forms. As recognized by the NFPA, however, only solutions containing more than 40% sodium hypochlorite by weight are considered hazardous oxidizers.
This made wood fibers the main raw material in paper, instead of textile fibers. Later the chemical pulping processes started dominating for many paper types. [2] Today the groundwood pulping mills are few, but the mechanical pulping processes employing refiners are still important in the Pulp and paper industry. The mechanical pulps are ...
The Kappa number estimates the amount of chemicals required during bleaching of wood pulp to obtain a pulp with a given degree of whiteness. Since the amount of bleach needed is related to the lignin content of the pulp, the Kappa number can be used to monitor the effectiveness of the lignin-extraction phase of the pulping process.