Guar gum improved electrolyte compatibility. These changes in properties result in increased use in different fields, like textile printing, explosives, and oil-water fracturing applications. Guar molecules have a tendency to aggregate during the hydraulic fracturing process, mainly due to intermolecular hydrogen bonding. These aggregates are detrimental to oil recovery because they clog the fractures, restricting the flow of oil. Cross-linking guar polymer chains prevents aggregation by forming metal – hydroxyl complexes. The first crosslinked guar gels were developed in the late ‘60’s. Several metal additives have been used for crosslinking, among them are chromium, aluminum, antimony, zirconium, and the more commonly used,
Hydrochloric acid in the production of polyvinyl chloride for plastic. In households, diluted hydrochloric acid is often used as a descaling agent. In the food industry, hydrochloric acid is used as a food additive and in the production of gelatin. Hydrochloric acid is also used in leather processing. Hydrochloric acid was discovered by the alchemist Jabir ibn Hayyan around the year 800 AD. Hydrochloric acid was historically called acidum salis, muriatic acid, and spirits of salt because it was produced from rock salt and "green vitriol" (Iron(II) sulfate) (by Basilius Valentinus in the 15th century) and later from the chemically similar common