Unlike acetone or ethanol, water in dental adhesive is difficult to remove during application. Residual water left in the adhesive has many potential problems, such as increased permeability of the cured adhesive and faster hydrolytic degradation. Too much water in the adhesive is very difficult to completely evaporate. Some adhesives, such as All-Bond Universal®, utilize an azeotropic amount of ethanol and water solvent system to ensure easy and complete evaporation of residual water. In addition, high water content results in higher dissociation of the acidic monomer, which leads to higher acidity (lower pH) and may reduce the shelf-life of a single bottle adhesive.