How do building owners replicate architectural elements unique to their historic properties without a huge investment in research and expense? One way is to take advantage of Abatron’s full-service Mold and Casting Shop. Our in-house team applies years of experience using Abatron’s mold-making products and a variety of casting compounds to create three-dimensional reproductions with remarkable detail. This article documents a recent project casting replacement capitals, providing a view of the process.
1. Preparing the model. The first step was to clean and prepare the surface of the capital serving as the model, ensuring no dirt or foreign material was present. Some minor cavities were repaired by filling them with WoodEpox®. Once the WoodEpox hardened, it was sanded and wiped down. The model was then coated with Primkote 8006-1™, a sealant. This prevents absorption of the release agent,
Abhesive 15-C™, which is applied so the mold can be easily peeled off of the surface of the capital.
2. Making the mold. To capture all of the characteristics of the capital, a mold was made using MasterMold®, a flexible, polyurethane compound that reproduces fine details. MasterMold was applied about 0.3 inches thick over the entire surface to make a durable, resilient mold that could be used for multiple castings.
3. Making the support mold. Next, a support mold was created to allow the flexible mold to keep its shape as the castings cure. The support mold for this model was created using a fiberglass cloth coated with resin for rigidity. Once the resin hardened, the support mold was removed.
4. Making the castings. With the flexible mold carefully placed inside the support mold and clamped down, it was time to begin mixing up the casting compound. The castings were made using gypsum, a pourable, high quality casting plaster. The gypsum was slowly mixed with water in a pail. A spray bottle was used to spray water into the mold cavity, which reduced the creation of bubbles as the casting material was poured into it.
Gypsum Mixed with Water Creates a Pourable Casting Compound
The gypsum was slowly poured into the mold. This was done in three sections to accommodate the curved shape of the capital. As one section would set up and begin to harden, the mold was rotated and braced so it was stationary for the next pour. A mixing stick was used to push the more fluid gypsum onto the prior section to eliminate any seam. As the second section set up, the process was repeated, and any gaps or voids in the mold were filled.
5. Removing the castings. Once the casting had fully hardened, it was time to remove it from the mold. The clamps that held the support mold and the flexible mold together were removed. Next, the flexible mold was released from the support mold. Once free, the flexible mold was slowly peeled away to reveal the finished casting. The process could now be repeated as often as needed for the project. Ten capitals were made from the above mold for a single project.
The Mold and Casting Shop at Abatron is pleased to bring results like these to our customers. If you have any questions about the mold- making and casting process, or to receive a quote, please contact Abatron at 800-445-1754.