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Silicone Molding: How To Make A Mold For Silicone Casting

Mark Lee

Today, there are numerous ways in which silicone is used to create molds. Plus, it’s also one of the most preferred means. If you look around the stores today, you’ll find that silicone molds are almost everywhere. And, it can be used for nearly anything as well. In the household use alone, it’s a favorite for cooking. Silicone molds last through more years than any other type of mold. Especially when they’re cared for and stored correctly. Plus, they’re also safe, versatile, and easy to use.

Here, you’ll learn more about silicone molds, its usage, and how molds are created for casting.

First, The Materials Needed

Before anyone can even begin with the process of creating silicone molds, it’s important to have a walk through with the needed materials and equipment. That way, you can have a better assessment of the budget that you need. You can also hunt for the materials, should they not be available in your hardware shop. But, if you intend to create silicone molds regularly, most of this equipment are those that you can use over and over again.

This list is thorough, but as you make more, you may also find yourself needing more supplies.

  • The silicone
  • The materials needed for the mold box (these are dependent on the size and the weight of the box you need to create, such as cardboard or wood)
  • Acetone, for cleaning up the excess mess
  • Notebook/paper/calculator for listing and calculating weights and writing down notes
  • Small brushes and mixing cups
  • Weighing scales and measuring cups
  • Knives and other cutting tools

Second, The Procedure

1. Select A Type Of Silicone Mold Making 

There is no one silicone mold that’s better than the other. The choice here really is all up to the specific purpose that you’re using the silicone mold for. You have to match it with the intention of ensuring that the best results are going to come out of it. That said, here are some of the most common types of silicone molding:

  • Poured Block Mold. This is one of the simplest types of mold. In this procedure, a mold box is necessary, which is also simpler to create.
  • Brush-On Mold. This kind of mold making method is also one of the simplest and easiest to do. As its name suggests, you brush on the cast to create the mold.
  • Poured Blanket Mold. This method uses a lesser mold rubber than poured block molds. Here, it’s necessary first to have a molded shell, which, unfortunately, may take more time and expertise to learn. In this method, removing casting is generally easier. Molds are thinner and more flexible. 
  • Shell Mold. This method has two parts. The first consists of a soft rubber. This is an actual duplicate of the original prototype. When it’s removed from the original, it’s unable to keep its form, because of its delicate material. Hence, a second layer, known as a rigid layer, is added.

2. Select The Silicone Rubber Type

Once you’ve had the type of silicone mold making figured out, now it’s about time for you to select the silicone rubber type. As is the case with the kind of mold making, the choice boils down to a matter of personal preference. There’s no one way that’s better than the other. And, the common goal is to have a smooth release, even for the difficult areas.

The general types of rubber to be used in silicone molding include:

  • Platinum-Cured Silicone Mold Rubbers. The advantage of using this type of silicone rubber is that it doesn’t shrink upon curing. And, after curing, the rubber also has a longer shelf life.
  • Tin-Cured Silicone Mold Rubbers. As for this option, one of the advantages is that it’s a little bit more affordable than the platinum-cured silicone mold rubbers.

3. Build The Mold Box

 The silicone box serves as the protection of the product that you’re trying to mold. In general, the box you’re making should be enough to fit at least 1/2′” of the material that’s needed. As the box is created, it’s imperative to glue all the sides together. This is to prevent any leaking from the prototype or the silicone mold. In addition, remember to wear gloves. Else, your fingerprints might show up on the finished product.

4. Fasten The Prototype

 The prototype here refers to the cast or the model of the silicone mold that you’re trying to create. This is what you’re going to put inside the mold box, once its quality is secured. Before you put in the prototype, the most crucial tip for you to remember is to fasten it securely. Pour in glue at the very bottom, to prevent the prototype from shifting and moving around sides.

5. Create And Pour In The Silicone Rubber

The creation of the silicone rubber is usually dependent on the instructions that come with the packaging. Be sure that this is followed through in full, and without any mistakes. As you mix the rubber, be sure not to hit the sides of the pail. Else, this might create a poor consistency or a bubbly one. You want your silicone rubber to be as smooth and flawless as possible.

Pour the silicone in the mold box until it reaches at least an inch above the highest point of the cast, prototype, or sculpture that you’re trying to mold. Leave it at room temperature for 24 hours.

6. Start Casting

Once the rubber has been fully cured, you can now start casting. Be very careful in removing the sides of your mold box. If you feel that the rubber still isn’t hard enough (even after 24 hours), then give it a little bit more time to cure. This silicone mold can now be used for whatever purpose you intended.

Third, The Properties Or Factors To Look Out For

When you’re creating a silicone mold, there are properties that you have to be conscious about. These will help you have better judgment as to whether or not the silicone mold you’re buying (or making) is of the best quality.

A couple of these properties to look out for include:

  • That it’s brushable and food-safe
  • That is has a low viscosity, meaning that it has a semifluid-like consistency
  • That it has an excellent molding detail
  • That it’s easy to use and stretch, without tearing

These abovementioned properties can show you precisely the reason why silicone molds are more expensive. If you shop for these at your local store, they are priced higher than other molds. Because of the process that it has to go through, it’s naturally more difficult than others. And, it takes a lot of expertise and caution, too. But, this price also comes in impressive quality. Hence, you can be better assured that you’re bringing home (or creating) a silicone mold that’s going to last through years.

Fourth, The Storage 

As aptly mentioned above, proper storage is also one of the most critical factors that come into play to increase the longevity of your mold. As is the case with any other thing, the more that you take care of an item, the longer it lasts. With silicone molds, however, this amount of care requires a little bit more than usual. This stems from the delicate nature of the materials that it’s created from.

Some tips to follow as to the proper storage of the silicone mold is as follows:

  • Store the silicone mold in a cool and dry place.
  • Keep the silicone mold away from direct light.
  • Clean the mold after every use with soap and water.
  • Keep the silicone mold on a flat surface. Else, the shape is going to be distorted.

And Now, The Functions 

The silicone molds, as you know it today, are used for many purposes. This is precisely the reason why it has gone to be so popular and in-demand too. Wherever you look in supermarkets, you’re sure to find at least a silicone mold here and another one there. But, now that you know the basics of silicone molding, you can even be a little bit more creative through a DIY. If there’s any shape or custom mold that you wish to create, it will now be more doable.

That said, here are some of the common functions today for silicone molds:

  • Healthcare and medical industry
  • Schools, especially in daycares and early childhood centers
  • Household, particularly the kitchen such as baking, cooking, and even storage purposes

Whatever the function, all the more, it’s essential for you to ensure that your mold is 100% accurate.

Conclusion 

With this step-by-step guide, it’s easy to see that silicone molding isn’t so difficult after all. If there’s any personalized mold that you’d want to create, now you have the liberty (and the skill) to do so. The materials are easy to find too. All you’ve got to do is to take a trip down to your hardware store, and you’re sure to find everything that you need for your silicone mold. With more practice, every mold that you’ll create will be even better than it used to be.