Abstract: An aqueous solution is provided for removing undesirable "heat discoloration" characteristics from a mold surface, the solution consisting essentially of about 17% to 21% by weight phosphoric acid and about 1% of non-ionic surfactant, the remaining portion being substantially water, with a small amount of colorant and/or fragrance being optionally added as desired. The method of use includes applying the solution to a mold surface of a mold half, the mold surface having undesirable "heat discoloration" characteristics thereon caused while heating the mold half for repair, and removing any residue after about 30 seconds or less thereafter. In particular, the undesirable "heat discoloration" characteristics normally occur after heating the mold half during the process of repairing a damaged mold surface or reworking a mold surface requiring an engineering change.