Cottle boards are essential tools used in mold making and slip casting in ceramics. When you have a model that you want to replicate through a plaster mold, you need to create a “box” around the model to contain the liquid plaster until it sets. This box, often referred to as a cottle, ensures that the plaster stays in place and forms an even, sturdy mold. If you’re working with ceramic projects that require precise replication, learning how to make and use cottle boards is vital.
In this guide, we’ll walk you through the materials and steps needed to create high-quality cottle boards for your mold-making projects.
What Are Cottle Boards?
Cottle boards are typically made of sturdy plywood and are assembled in a way that forms a temporary box around the model or object you want to cast. This box allows you to pour liquid plaster around your model, creating a mold that can be used in ceramics, sculpture, and various other casting techniques.
Cottle boards are adjustable and reusable, making them a great addition to any artist’s toolkit. Once you understand the process, you can easily make your own custom-sized boards for a variety of projects.
Materials Needed for Making Cottle Boards
Before you begin, gather the following materials:
- Plywood (6″ to 10″ high): Use good-quality plywood such as oak-laminated or birch, cut into four pieces that are 6 inches wide and 1.5 to 2 feet long. The height of the plywood should be determined by the size of your project.
- 2×2-inch wood stock: You’ll need four pieces of 2×2-inch stock to reinforce the cottle boards.
- Wood glue: A strong adhesive for bonding the plywood and wood stock together.
- Clamps: Four clamps to hold the pieces together while the glue dries.
- Drill: For drilling screws into the boards to ensure they are tightly secured.
- Nails or screws: Used to reinforce the glued joints after drying.
Step-by-Step Guide to Making Cottle Boards
Step 1: Prepare the Plywood
Start by cutting your plywood into four equal pieces. These pieces will form the walls of your cottle. The standard dimensions are 6 inches wide and 1.5 to 2 feet long, but you can adjust this based on the size of the object you’re casting. Make sure the plywood is of high quality, such as oak-laminated or birch, to ensure durability and longevity.
- Pro Tip: Sand the edges of the plywood to remove any rough spots or splinters that may affect the mold-making process.
Step 2: Attach the Wood Stock
Next, you’ll attach a 2×2-inch wood stock to one end of each plywood piece. These stocks serve as reinforcement and help the boards stay upright when forming the cottle.
- Apply wood glue to one side of the 2×2-inch stock.
- Align the stock flush with the edge of the plywood, ensuring the edges are straight and even.
- Clamp the wood stock to the plywood using a strong clamp, making sure the stock is firmly pressed against the board.
- Repeat this process for all four plywood pieces.
Step 3: Let the Glue Dry
Allow the glue to dry completely. This may take several hours depending on the glue you’re using, so it’s important to give the boards enough time to bond securely.
- Tip: Check the manufacturer’s instructions on your wood glue for drying times to ensure the bond is strong before moving to the next step.
Step 4: Drill and Reinforce with Nails or Screws
Once the glue has dried, reinforce the bond between the plywood and the wood stock by drilling holes and inserting nails or screws. This adds extra strength to the joint, ensuring that the cottle boards will hold up during repeated use.
- Using a drill, create two or three holes along the length of the 2×2 stock where it connects to the plywood.
- Insert nails or screws into these holes to secure the two pieces together.
Step 5: Assemble Your Cottle
Now that you have your four cottle boards ready, you can assemble them around your model to create the box for pouring plaster. To do this:
- Stand the four boards upright around your model, forming a square or rectangular box. The boards should be flush with the base.
- Use clamps or a temporary binding system to hold the boards together securely.
- Ensure the corners are tight and sealed to prevent plaster from leaking out when poured.
Why Use Cottle Boards in Mold Making and Slip Casting?
Cottle boards are a versatile and reusable solution for mold making. Here’s why they are essential in ceramic and casting projects:
- Adjustability: Unlike permanent molds, cottle boards can be adjusted to fit a variety of sizes and shapes. This flexibility is crucial for artists working on custom or unique pieces.
- Cost-Effective: By making your own cottle boards, you save money compared to buying pre-made ones. The materials are affordable, and the boards can be reused for multiple projects.
- Ease of Use: Once assembled, cottle boards provide a stable and easy-to-manage box for casting plaster molds. They allow for a clean and controlled pouring process, ensuring accurate and professional results.
Tips for Successful Mold Making with Cottle Boards
- Ensure a Tight Seal: Make sure the cottle boards are tightly clamped together to prevent any plaster from leaking during the casting process.
- Choose the Right Size: The size of your cottle boards should match the dimensions of your project. Larger models will require bigger boards, while smaller models can use shorter or narrower boards.
- Use High-Quality Plywood: Good quality plywood such as birch or oak-laminated will ensure that the boards last longer and are less likely to warp over time.
Conclusion
Making your own cottle boards for mold making and slip casting is a simple yet essential process for any ceramic artist or sculptor. By following the steps outlined in this guide, you can create durable and reusable cottle boards that will serve you well in a variety of projects. With the right materials and tools, you’ll have everything you need to start casting high-quality molds with precision and ease.