The Sirchie Hard-Core Blue is an all-purpose, gypsum-based casting material that will result in a high-strength, accurate reproduction when properly used. Familiarity with the preparatory process and the material itself is essential. Trial casts should precede any actual evidential casting. Hard-Core Blue is supplied in pre-measured quantities for the required 2:1 ratio for casting. The HCB100 is 6 lbs. of compound to 48 oz. of solution.