Regardless of the type of project you are working on, you are going to need a mold to form your concrete. Typically the nature of the project will dictate the type of mold required. Here is an overview of some of the options available:
Pre-made Molds: For projects involving sinks, planters, and furniture pre-made molds are available for purchase. Pre-made molds are typically made of some type of plastic, rubber, or fiberglass. The molds that are sold on the Buddy Rhodes website are made of fiberglass and are extremely durable. You can use the same mold for hundreds of castings. Because of the cost associated with pre-made molds they are generally purchased with multiple castings in mind.
Making Molds out of Melamine: For most projects involving straight lines such as countertop slabs, square or rectangular shapes, melamine is the material of choice. Melamine is a plastic coated particle board sold in sheets like plywood or other sheet goods. Melamine is relatively inexpensive and can be used a few times. Some curves can be accomplished with the use of thin melamine or Formica. Here is an example of project (SEAT Project in San Francisco) that was made with melamine:
Rubber: Rubber is typically used for custom sinks or design element. The rubber is poured into a vessel (often made of melamine) and once cured the rubber mold can be used for multiple casting.
Fabric Formed: Fabric forming is a relatively new technique to the decorative concrete industry and allows for unique and/or “flowing” designs. The fabric formed mold is created by stretching fabric in the desired shape and than coating with a fiberglass resign. The resulting mold can be very organic or fit a very specific design need. The picture below illustrates a fabric formed mold and the resulting guitar theme sink for a project in Nashville.
Plaster: Plaster molds can be used for creating curved shapes similar to furniture molds that are sold by Buddy Rhodes. Working with plaster is an acquired skill involving craftsmanship and understanding timing of the plaster materials. When creating a plaster mold, typically a “positive” is cast and then a “negative” which is used as the final mold. Plaster wont have the durability of fiberglass, but if you have the know-how it can be a more economical option. Here’s a picture of a mold Buddy created a few months ago for a custom table project.