Acid free tissue paper is used for protection and conservation purposes. It’s free of acids that normally cause the paper to deteriorate as well as the items that are being protected. There are two types of tissue paper – buffered and unbuffered. Unbuffered paper has no buffering layer to prevent future acidity. It’s mostly used with surfaces or items that are susceptible to higher pH levels. Unbuffered paper usually has a pH neutral level of 7.0 to 7.5, whereas buffered paper has a pH neutral level of 7.5 to 9.5 and also has an extra alkaline layer that fights the reactions in the material and the environment, making the items protected for a much longer period (pH level measures the level of acidity and alkalinity. The scale ranges from 0-14, 7 being the neutral level).