PURPOSE: To recover glass surface of a little opacity having a white opaque pattern which is caused by deterioration due to secular change, erosion and dirt so as to be a transparent glass surface by a simple treatment at the job site.

CONSTITUTION: An acrylic resin-based paint having super low viscosity is applied on the glass surface whose surface is deteriorated and is opaque a little. Also a dyestuff is dissolved in a solvent and is mixed with the acrylic resin to prepare a colored transparent coating agent. Thus, the transparency can be recovered and this method is applicable for another fields. Among the acrylic resin-based paints, an acrylic urethane resin is preferably used because it has excellent transparency. Also an ultraviolet-curing resin is preferably used.