Molding Process

23 Jul, 2020

1288 Words

The bronze molding process is one of the most important steps in creating a sculpture. Without a high quality, durable mold, your final product will take on the sub-par shape of the casing in which it is formed. Or, you might not even make it to a final product if the mold is faulty to the point at which it might leak or break. To help you achieve the best possible final product, here we break down the intricacies specifically of the molding process in the overall procedure of creating bronze sculptures.

Types of Molds

The most common materials that molds are made out of are a high-quality silicon rubber, or a polyurethane compound. There is also another option you might come across through a brand known as Smooth On that uses a latex based mold that also works well. Some sculptors switch between different types of materials based on the detail or size of the project. However, other artists swear by a certain type of molding material and always stick with that. Ultimately, it is up to you depending on what you are most comfortable with.

Steps to Prep for the Molding Process

Before delving head first into the molding process itself, it is important to understand the steps leading up to it to make sure that your project is being properly prepared.

Traditionally, the first step in creating a bronze sculpture is that an artist would start by making an original out of clay.

Next, an armature is created, usually made out of pipe, wire, or aluminum, in order to help support the weight of the clay model.

The following step before the molding process begins involves touching up every single detail of the clay in order to get it as close to the finished product as possible. This is because any scratch in the clay, however small, will imprint on the mold itself, thereby remaining present in the process all the way through to its completion. It is also important to be sure to let the clay dry thoroughly before moving onto the molding process, or else you will be at risk of needing to start the clay portion over from scratch as the mold will not form properly if the material is damp or wet. Once your clay figure is complete and dry, you are set to begin the molding process itself.

It is good to note that these are the classic steps leading up to the molding process of creating a bronze sculpture. However, it is possible in today’s day and age to use 3D technology to help increase the accuracy of the details of the project, as well as save time and money with the process. This can be done in a few ways:

  1. One is creating a rough version of the clay model, then 3D scanning it to refine and remodel it electronically in order to enhance the details, before finally printing a more accurate version by 3D printer to then create a mold of.

  2. The other option is to create the model you want to mold entirely digitally, without having to even scan a rough clay version, that you can then 3D print a detailed version of before moving on to the next step of creating the mold around it.

  3. You can also use a 3D printer to print the mold itself.

There is no “right or wrong” way to create art of course, so it is up to each artist with regard to their own creative process. At ArtDigital, we prefer the specificity that is possible through today’s technology, and therefore integrate 3D technology into our design process.

The Molding Process- Bas Reliefs

If you are working with the bas reliefs method of sculpting, you would create your own mold via the clay preparation steps mentioned above. Once the clay model is complete, you then would choose your preferred material for the mold: high-quality silicon rubber, polyurethane compound, or latex. Your choice of material is then painted over the surface of the dried clay figure over the course of a number of days with a chip brush. Ideally, you would have three to five layers, leaving at least 24-hours in between applications. The exact room temperature will have an effect on the length of time you will need in between layers.

Once your three to five layers of the silicon, polyurethane, or latex are complete, you will need to add a firmer outer layer in order to hold the shape of the more supple inner layer. The outer layer is often faceted out of materials such as epoxy, resin, plaster, or Hydrocal. This outer layer is referred to as “the mother mold”. Once it has completely dried as well, the clay is then removed from the mold. Often, this results in the clay original being destroyed due the nature of separating the two pieces from each other; but not to worry, as you are now left with the negative of the original, which allows you to move on to the next step of the process further detailed in the section below.

Something important to note regarding the molding process is that, for very large or complex projects, it will need to be done in sections. The person making the mold will analyze the project to determine where the best place to have the parting lines will be. Those pieces will then be rejoined later.

The Molding Process- 3D Technology

With today’s technology, 3D printing has revolutionized the way artists can work on a sculpture, either by 3D scanning a clay version to create a digital model off of, by creating the original model design directly from the computer, or by printing the mold itself from the computer.

Some of the best types of 3D modeling software include:

3D Max Maya Rhino Zbrush Different types of 3D printing include:

MEM– considered high strength and low cost. Not the best accuracy rate. 3DP– This is primarily used for small objects. Can be helpful if you want to print in color. SLA– Helpful for small sized projects. The accuracy is competent. SLS– This model can bring out all different sorts of materials- even more difficult ones such as various types of metals. Two of the largest benefits of being able to use 3D printing for artists are the ability to increase the level of accuracy and detail of the model or mold, in addition to saving valuable time, and therefore, money.

Steps After the Molding Process

To give you a brief outline of how the project moves from the mold to the finished product, the next step involves creating a positive form wax replica from the negative you’ve just made. This is usually completed in about four stages with varying degrees of temperature. After the wax finally cools off, you are then left with a wax positive of the mold, at which point you continue on with the usual remaining steps of the bronze sculpture process:

Pouring a Wax Replica Wax Chasing Spruing a Wax Ceramic Shell or Investment Casing Melting or Burning Out the Wax Casting/Pouring the Bronze Break Out Metal Chasing Metal Welding & Assembly Sandblasting or Bead Blasting the Bronze Patinazation Finished Product You can learn more about each of these steps in our article titled, “How Are Bronze Sculptures Made?”

About ArtDigital

ArtDigital will work with you every step of the way to create a custom order, work of art, or piece of jewelry from the idea’s inception, through the molding process, and finally to the beautiful, finished product. ArtDigital prides itself on expert craftsmanship to materialize ideas that raise your business above the competition. Contact us today to learn more about our various offerings with no obligation.

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