Hanji, a traditional Korean paper, has a porous structure and hydrophilicity due to cellulose’s hydroxyl group (-OH). A glue catcher is commonly used to prevent spreading. Glue-mixed water used for the glue catcher is prepared by mixing natural animal adhesive glue and alum (KAl(SO₄)₂•12H₂O). The alum mixed with the glue-stirred water acts as a bridge connecting the glue and prevents the ink and pigment from spreading so that the color adheres well to the Hanji paper, the base material. However, sulfate ions (SO₄SUP2-/SUP) contained in alum combine with water to form sulfuric acid, which causes acidification. It is deacidized by penetrating alkaline substances such as magnesium oxide (MgO) to prevent such acidification. After applying the glue to the Hanji paper, the deterioration proceeded. The deacidification treatment with magnesium oxide after the deterioration was carried out to evaluate the behaviors of physical, mechanical, and pH neutralization reaction of the Hanji paper, and after deacidification, the general strength properties were increased in mechanical properties. In the optical properties, the L* value increased as the deacidification treatment proceeded. It was confirmed that the pH value significantly reduced the oxidation of Korean paper in the glia count and neutralized the deacidification treatment.