The Gold Standard Phosphoric Acid Etchant Ultra-Etch is a viscous 35% phosphoric acid solution. The optimum level of viscosity, along with use of the Blue Micro or Inspiral Brush tip, facilitates precision placement and superior control. Contemporary studies demonstrate Ultra-Etch is the optimum "total etch" etchant. Ultra-Etch is just viscous enough to prevent migration on a vertical surface. However, it can penetrate into the smallest fissures of occlusal surfaces due to physical and chemical properties that promote capillary action. The optimum viscosity maintains a thick enough layer to prevent premature drying. Product Features - Viscous 35% phosphoric acid solution - Ideal viscosity facilitates precision placement and superior control. - Fumed silica etchant rinses off cleanly.