Bell Casting & Tuning Cast Bells
The art of bell casting can be traced back all the way to the 12th century. The earliest cast bells recorded are said to have been made from pottery and evolved using stronger materials like bronze.
Over time the general process of casting a bell has since remained fairly much the same. With each foundry using their own expertise and traditions to put their unique touch on bell casting, you can see the process and techniques vary from company to company. For centuries, bells have been a notable symbol in many societies. Overtime, advancements in technology have made the way we cast bells more efficient.
The Bell Casting Process
The most commonly used bell metal used today is made up of 77% copper and 33% tin. When combined, these two compounds create nice sounding bells of superior quality.
- Molding – Once a bell design has been established, it’s time to start the molding process of the bell. An exact model of the outer part of the bell is made using either stone, brick or coke. Once the the model has been made, it is then covered with sand or a type of soil call loam. Between the coating of each sand or loam layer, which usually consists of 3 layers, the bell is placed in a kiln to dry. Once the final layer of sand or loam has been applied, designs and inscriptions can be made into the bell.
- Pouring – After the outer part of the bell has been molded, it is then lowered into an inner bell mold and clamped together leaving space in between each piece. This space between both molds is there to allow for a molten material, usually tin, bronze or cement, to be poured in between. Once these 2 pieces are clamped together, the molten material is then poured in between them.
- Cooling – After the molding of the bell is complete, the bell needs to cool for a few days. Some bell casting companies will lower the bell into a pit or straight into the ground, depending on the method they choose to use and the traditions of the foundry. Depending on the size of the bell, the cooling process can take a couple days. For larger bells the cooling process can take up to a whole week.
Bell Foundry Sand Casting Versus Lost-wax Bell Casting
The sand casting process is a process where a molten metal i.e., iron, steel, etc. is poured into two sand molds to create metal parts. After the molten metal is poured and cooled, the mold can then be split apart and the new pattern can be taken out. Lost wax bell casting is a method that has been used for over 5000 years. This process is when a molten metal, in this case usually a bronze or gold, is poured into a mold that has been created by a wax model of the originally cast bell.
Loam or sand casting has some limitations surrounding the decorative features on the bell however running into this isn’t common. We can apply most artwork and inscriptions in the loam bell casting process. The biggest advantage to sand-casted bell is that it has a superior bell ringing tone and molecular structure that lost wax cannot achieve. Lost wax bells have a tendency to have a harsher or “colder” tone.
Since early civilization, bells have been symbols of significance across multiple cultures. From hanging outside churches to ringing in town squares, bells have been a focal point for many of the cities and churches. With advances in technology, we’ve seen the bell casting process transform become more efficient, while still pulling from ancient casting practices.
Cast Bell Tuning
Bells are casted uniquely to ensure certain amounts of metal can be removed to adjust the harmonics within. Removing these metals allows the bell-operator to accurately tune the bell and adjust the harmony. Metal from bells can’t be added, so the process of tuning should be done carefully and by an experience professional. There are five core principals of bell tuning:
Over the years, tuning instruments have evolved. Some of these innovations include a tuning lathe, which can manually remove metals from the inside of the bells the help adjust the tone. However, some bell-founders still like to do the tuning process by hand for an individualistic sound.
McShane can provide you with new cast bells or even refinish your existing older bells!