The ASTM D1994-07 (2015) standard test method is used to determine the acid value of hot-melt adhesives. Determination of the acid value is critical to understanding the gluing performance of hot-melt adhesives and their wettability to substrates. Acidic hot-melt adhesives improve adhesion to polar non-porous surfaces, but may be corrosion resistant to conventional steel Adhesive equipment. Therefore, knowing the acid value helps to choose whether to use corrosion resistant equipment. This method is suitable for soluble hot-melt adhesives and requires a solution Color of Light or Medium Color. This standard helps ensure the suitability and equipment selection of hot-melt adhesives in practical applications.