PURPOSE: To prevent mal-odor from evolving during handling and working by making combination use of a limonene monomer and a limonene dimer with a urea resin at the time of forming molding sand for shell mold casting by coating urea base resin on the molding sand.

CONSTITUTION: As the molding sand used for a mold for shell mold casting, it is prepared by mixing 100pts.wt. molding sand, 2W6pts.wt. urea-base resin, 0.2W 1.5pts.wt. a hardener, 0.02W0.2pt.wt. limonene monomer and 0.001W0.05pt.wt. limonoene dimer. In this case, a furan-modified urea resin or phenol-modified urea resin is used for the urea-based resin, and ammonium chloride, a mixture of ammonium chloride and urea, phosphoric acid, magnesium chloride, etc. are used for the hardener. This molding sand does not evolve any unpleasant mal-odor during molding or pouring of molten metal into the mold.