The mortar and pestle is one of the oldest tools used on the kitchen. The Mastro Mortar and Pestle is based on an original 19th century design from Italy. Like the original our Mortar is solid cast bronze. A heavier piece intended to remain stable and aid in the grinding of fresh herbs.
Mortar 3D Design
A 3D design was created using Solidworks. The outer radius of the mortar is 3 inches. Note that the inner radius of 2.5 inches.
Pestle 3D design
The pestle was also designed using Solidworks. The curve on each end of the pestle matches the the inner bowl of the mortar and allows for an easier grind.
Prototypes and early production
Starting at the left with the 3D print. The print of the original design was used to create a mold. The middle version is a resin version used to test the mold and will be used as a reference for wax and later bronze versions. Right is a wax version that will be used for the lost wax method
Creating the Wax mold
On the left you can see the mortar mold and on the right in the background the mold for the pestle. The method is called lost wax because each time the bronze if poured the wax is melted out and "lost". This mold is used to create each wax version
Embellishing the wax
Each wax comes out of the mold in the original smooth form. Then the wax is embellished by hand to add a one off unique design. Each wax is destroyed in the process so each mortar design is unique.
Creating the mold for the bronze casting
More wax is added to create a network of wax pipes, called sprues and gates. These pipes first will allow the wax to escape as it melts. Later, they will enable the molten metal to flow evenly throughout the mold and will also let air escape as the metal is poured in.
Mortar and Pestle bronze mold
Another view of the final mold drying before the bronze is poured. The white/gray material is a finely granulated ceramic applied to the surface of the model and its pipes until it becomes thick and coarse. The result, now called an “investment mold,” is then dried and heated. This causes the wax to melt and flow out of the mold, leaving a space between the fire resistant clay model and the investment mold. This is why this method is called the lost wax process.
Raw bronze cast
Molten bronze (over 2,000 degree Fahrenheit) is then poured into the investment mold, filling the space left by the “lost” wax. When all is cool, the cladding and investment mold are broken and the metal appears.
After the bronze is poured and the piece has cooled the next step in the process is called "chasing the wax". It involves removing the gates and adding back any detail lost in the process from wax to bronze.
Preparing for the patina
The bronze is heated evenly and takes on a straw yellow or honey color depending on the temperature and patina to be used.
Applying the patina
The patina is applied to the hot bronze. Exact steps depend on the desired effect. In the case the desired effect of the patina was to highlight the contrast in the textures. No patina is applied to the inside of the mortar bowl.
A detailed view of the mortar and pestle with contrasting patina pattern.