in certain instances high shear rates , such as when a fracturing fluid is pumped downhole , tend to degrade the viscosity of low polymer guars in low salinity environments . in the past in order to improve guar efficacy a delayed cross - linker such as ulexite or colemanite , both boron ores , was added . recently it is been found that by adding a weak base , the overall viscosity of the guar was enhanced . the fracturing fluid typically includes a base fluid , in this case low salinity water , a gelling agent , a delayed crosslinker , a weak base , and other additives useful for treating a well such as friction reducers , buffering agents , clay control agents , biocides , scale inhibitors , chelating agents , gel - breakers , oxygen scavengers , antifoamers , crosslinkers , wax inhibitors , corrosion inhibitors , de - emulsifiers , foaming agents , or tracers .