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,
Gum over platinum acid, the print is washed in 1% potassium metabisulfite after proper development in water. Interested individuals should read up on the process before attempting, as the chromic acids are very dangerous to work with. The mechanics of the gum portion is not entirely known; what occurs is the exposed gum is hardened and becomes water-insoluble. Upon washing, the unexposed portions wash away, leaving the white paper exposed. The technique is related to platinum printing. Gum over platinum Gum over platinum is a historical chemical photographic process, which was commonly used in art photography. It is a very complex process, in