Abstract: A supporting structure for a decalcomania wherein the decalcomania is inserted into an aqueous solution prepared by adding a reagent to water or into a quantity of mixed aqueous solution prepared by dissolving a reagent in a quantity of suitable solvent and then mixing this solution with a quantity of water and wherein a coating (6, 3A) of a water soluble separating agent is applied over the decalcomania and wherein the dissolving speed of the coat (6, 3A) is selected to be in accordance with the reaction speed of a coloration reactant or a chromogenic substance such as a dye previously added to the coating (6, 3A) of the water soluble separating agent such that a color change will be visually present when the optimum time for transfer of the decalcomania occurs.