How to Build an Epoxy Mold Casting for River Tables and Large Casting Projects

Creating an epoxy mold casting is a critical step in making projects like river tables or other large casting works. In this guide, we will take you through each stage of the process, from preparing your workspace to assembling the mold and eventually demolding your finished project. Follow these steps to build a mold casting that will help you achieve a successful and professional result.

Preparing Your Workspace for Mold Casting 

To begin your mold casting project, start by setting up a clean and organized workspace. It is essential to have a worktable where you can comfortably build and use your mold. You should ensure that you can easily access all areas of the mold cavity. A sheet of polyethylene (vapor barrier) placed on the worktable will ensure that any spills are quickly cleaned up. Secure the polyethylene sheet with tape along the edges to keep it in place.

Choosing Materials for Your Mold Casting

When it comes to materials for mold casting, we recommend using any sheathing tape to line the base and walls of your mold. For the structure of the mold itself, materials like melamine, medium-density fiberboard (MDF), or smooth plywood are perfect. Here is a list of materials to consider when building your mold and how they interact with epoxy:

Epoxy will stick to:

• Wood

• Glass

• Aluminum

Epoxy will not stick to:

• Sheathing Tape / Tuck Tape

• High-Density Polyethylene (HDPE)

• Teflon

• Polyethylene

• Polypropylene

• Nylon

• Mylar

• Silicone

Choosing the right materials for your mold casting will help ensure a smooth and easy casting process.

Watch a video on our YouTube channel on how to create a simple epoxy casting mold:

Designing Your Mold for Casting

Designing your mold is an essential step in the mold casting process. Here’s a basic layout of a mold design. When you’re cutting pieces for your mold, make sure to account for wall thickness. The height of the walls should exceed the size of your wood slab or embedded object, leaving at least ½” above the pour level. This extra space will help prevent leaks and will also make it easier to disassemble your mold later.

Preventing Epoxy Adhesion to Your Mold Casting

One of the most important steps in mold casting is preventing the epoxy from sticking to the mold. To do this, cover all interior surfaces of your mold cavity with any sheathing tape. This tape will create a barrier between the epoxy and the mold, making it much easier to remove your project once the resin has cured. Ensure that the tape is smooth and sealed without gaps to avoid any adhesion issues.

Assembling Your Mold for Casting

Once you’ve lined the cavity with mold release tape, it’s time to assemble your mold. Start by drilling pilot holes in the base and walls to make assembly easier. Use screws to attach the walls to the base of the mold. Screws will allow you to easily disassemble the mold later, which is essential for reusing it in future mold casting projects. Additionally, applying a bead of silicone to the base of the mold, where the walls meet, will help prevent leaks and ensure a more durable seal.

Sealing the Mold Casting

Before you can begin casting your epoxy, it’s important to ensure that the mold cavity is free of dust or other contaminants. Clean the cavity with a lint-free cloth soaked in denatured alcohol to remove any debris. After cleaning, apply a bead of silicone along all the inner joints of the mold to ensure that the epoxy does not leak during the pouring process. This is similar to caulking a bathtub. Let the silicone cure according to the manufacturer’s instructions before you proceed with the casting.

For sealing, the best choice is Artline Crystal Epoxy Resin. This high-quality, crystal-clear resin creates a strong and smooth coating, preventing air and moisture from penetrating the wood. Its advanced formula ensures excellent adhesion and durability, making it the ideal option for preparing the surface before the main pour.

Tip: If you’re new to mold casting, consider adding a silicone fillet to the outer edges of your mold for extra leak protection.

Setting Up for Your Epoxy Pour

Once your mold is sealed and ready, you need to prepare the surface for the epoxy pour. Ensure the mold is level on the worktable. If necessary, use blocks of wood or other supports to raise the mold and make it easier to access the base when clamping your wood slabs or other objects inside. Use shims, washers, or other materials to adjust the mold’s level as needed.

Once the mold is positioned, add the wood slab or embedded item to the cavity. Secure it with clamps to prevent it from floating during the casting process. It’s important to use a block of wood covered with mold release tape between the clamps and your project to prevent the clamps from bonding to the resin. You can also use weights, covered in mold release tape, to help keep the object in place during the pour.

Warning: If your wood slab is warped, excessive clamping force can cause the mold to warp as well. To prevent this, add a stiffener to the mold, such as a second layer of melamine or MDF, to keep the mold from twisting.

Mixing and Pouring Your Epoxy for Mold Casting

With your mold prepared and your object securely in place, it’s time to mix the epoxy. Pour depth, multi-layer pours, and cure time for your epoxy. Be sure to follow the guidelines carefully to achieve the best results in your mold casting project.

For deep and large-volume castings, Artline Wood PRO Epoxy Resin is the perfect choice. Specially formulated for woodworking projects, it is particularly well-suited for creating river tables, countertops, and other wood-based designs, providing exceptional durability and a strong bond with natural materials. Its slow-curing formula allows for thick pours without overheating, making it the ideal solution for professional-quality results.

Demolding Your Project After Curing

After your project has fully cured, you can begin the demolding process. Start by removing the walls of the mold, being careful not to damage the casting. Use a putty knife, prybar, or wedges to gently release the casting from the mold. The added base material will provide leverage points that will help you easily remove the project.

For further assistance and inspiration, check out video tutorials on our YouTube channel. Be sure to click the notification bell and give a like to the videos. You can also follow us on Facebook and Instagram, and visit our website at artline-resin.eu for more tips and advice on mold casting.