The Ultimate Guide to Choosing and Using Best Molds for Resin Casting

Updated: 12 Apr 2023



Resin is a type of synthetic material that has become increasingly popular in the crafting community. It is a versatile material that can be used to create a variety of unique and beautiful items, including jewelry, home decor, and art pieces. One of the essential factors in resin casting is choosing the best molds for resin.

Epoxy molds determine the shape and size of the final product, and selecting the right one can make a significant difference in the quality of the finished item.

In this guide, we will discuss the importance of selecting the appropriate molds for resin casting and provide tips for choosing the best ones for your project.

Table of Content
  1. Introduction:
  2. Types of Resin Molds For Casting:
    1. Silicone Molds:
      1. Pros:
      2. Cons:
    2. Epoxy Molds:
      1. Pros:
      2. Cons:
    3. Plastic Molds:
      1. Pros:
      2. Cons:
  3. Choosing the Right Mold:
    1. Size:
    2. Shape:
    3. Material:
  4. Tips for Using Molds for Resin:
    1. How to Properly Prepare Molds Before Casting Resin
    2. Clean the Mold:
    3. Apply Mold Release Agent:
    4. Seal the Mold:
  5. How to Avoid Common Mistakes When Using Molds
  6. How to Properly Remove Cured Resin from Molds
  7. Best Resin for Molds:
    1. Epoxy Resin:
    2. Polyurethane Resin:
    3. Polyester Resin:
  8. Making Your Own Molds:
    1. Materials and Tools Needed:
  9. Preparing the Original Object:
    1. Mixing the Silicone Rubber:
    2. Pouring the Mold:
    3. Curing Time:
    4. Removing the Mold:
    5. Using the Mold:
  10. Care and Maintenance of Molds:
    1. Clean Your Molds After Each Use:
    2. Store Molds in a Cool, Dry Place:
    3. Use Mold Release:
    4. Avoid Using Sharp Tools on Molds:
    5. Keep Molds Away from Pets and Children:
  11. FAQs:
  12. Conclusion:

This article aims to help beginners understand the basics of resin casting and how to choose the right molds to achieve their desired results.

We will cover topics such as different types of molds, the materials used in making them, how to prepare molds for casting, and how to avoid common mistakes. By the end of this guide, you will have the knowledge and confidence to create beautiful resin crafts with ease.

Types of Resin Molds For Casting:

Silicone Molds:

Epoxy Silicone molds are one of the most popular types of molds for resin casting. They are flexible and durable, which makes them easy to use and long-lasting.

Silicone molds for epoxy are available in a wide range of shapes and sizes, making them suitable for a variety of different projects.


They are also reusable and easy to clean, which makes them a cost-effective option in the long run. However, epoxy silicone molds can be more expensive than other types of resin molds and may not be suitable for larger projects.


  1. Flexible and easy to demold from
  2. Reusable for multiple castings
  3. Can capture fine details and textures
  4. Good for intricate shapes and designs


  1. More expensive than other mold types
  2. Can be prone to tearing or distortion if not handled properly
  3. Not ideal for large or heavy castings as the flexibility can cause warping

Epoxy Molds:

Epoxy molds are another popular option for resin casting. They are made from a type of plastic that is strong and durable, which makes them suitable for casting larger pieces of resin. Epoxy molds are also available in a range of shapes and sizes and can be reused multiple times.

However, molds for epoxy can be more difficult to clean and may require special care to maintain their durability.


  1. Durable and long-lasting
  2. Can be made at home using epoxy resin and a mold release agent
  3. Ideal for larger castings as they are rigid and less likely to warp


  1. Can be difficult to demold from, especially for complex shapes and designs
  2. Can be brittle and prone to cracking or breaking
  3. Often require a release agent to prevent sticking to the mold

Plastic Molds:

Plastic molds are an affordable option for resin casting. They are available in a variety of shapes and sizes and are easy to use.


However, plastic molds are not as durable as silicone or epoxy molds and may need to be replaced more frequently. They can also be more difficult to clean and may not be suitable for more intricate designs.


  1. Inexpensive and widely available
  2. Can be used for a variety of casting materials, including resin, plaster, and concrete
  3. Good for simple shapes and designs


  1. Not suitable for capturing fine details or textures
  2. Often require a release agent to prevent sticking to the mold
  3. Not reusable and can only be used for a single casting.

Silicone molds are flexible and durable, making them a popular option for a wide range of resin casting projects. Epoxy molds are strong and suitable for larger pieces, while plastic molds are affordable and easy to use. Each type of mold has its own pros and cons, so it is important to choose the right mold for your specific project.

Choosing the Right Mold:

When it comes to resin casting, choosing the right mold is crucial to the success of your project. Here are some factors to consider when selecting a mold:


The size of the mold will determine the amount of resin needed for your project. Make sure to choose a mold that fits the size of your project.


Consider the shape of the mold and how it will affect the finished product. Some resin molds have intricate details that can add a unique touch to your project.


As discussed earlier, there are different types of molds for epoxy made from different materials. Consider the pros and cons of each material before making your selection.

Common shapes and sizes used for resin casting include:

  • Round: Round molds are great for creating coasters, jewelry, and paperweights.
  • Square/rectangular: These molds are great for making small trays, decorative tiles, and other flat objects.
  • Geometric: Geometric molds can add a modern and unique touch to your resin projects.
  • Organic: Organic molds include shapes such as leaves, flowers, and shells. Organic molds for epoxy are great for creating nature-inspired resin pieces.

If you’re looking for unique mold ideas, consider:

  1. Using a 3D printer to create your own custom molds.
  2. Making your own molds using silicone putty.
  3. Upcycling household items, such as candy molds, soap dishes, and ice cube trays, into resin molds.

By considering these factors and exploring different shapes and sizes, you can choose the right mold for your resin casting project and create a unique and beautiful finished product.

Tips for Using Molds for Resin:

Resin casting can be a rewarding experience when done correctly. Here are some tips for using molds for resin casting:

How to Properly Prepare Molds Before Casting Resin

Before pouring resin into a mold, it’s important to prepare the mold properly. Here are some steps to follow:

Clean the Mold:

Clean the mold thoroughly with soap and water to remove any dust, debris or residue.

Apply Mold Release Agent:

Apply a mold release agent to the mold to help prevent the resin from sticking. Some popular options include silicone spray, cooking spray, or petroleum jelly. Be sure to follow the manufacturer’s instructions for the specific mold release agent being used.

Seal the Mold:

For molds that are not made of silicone or epoxy, it’s important to seal the mold with a thin layer of resin or a clear varnish. This will help prevent leaks and ensure a smooth surface finish.

How to Avoid Common Mistakes When Using Molds

Here are some common mistakes to avoid when using casting molds for resin:

  1. Overfilling the mold: It’s important to only fill the mold up to the recommended level. Overfilling can cause the resin to spill out of the mold and ruin the project.
  2. Under-mixing the resin: Resin needs to be mixed thoroughly before pouring into a mold. Failing to do so can result in the resin not curing properly or having air bubbles.
  3. Not using enough mold release agent: Failing to apply enough mold release agent can result in the resin sticking to the mold and being difficult to remove.
  4. Using molds that are too small or too detailed: Molds that are too small or too detailed can be difficult to work with and may result in the resin not curing properly.

How to Properly Remove Cured Resin from Molds

Once the resin has cured, it’s time to remove it from the mold. Here are some steps to follow:

  • Gently flex the mold: Depending on the type of mold, gently flex the mold to help release the resin. Be careful not to use too much force, as this can damage the mold.
  • Use a release agent: If the resin is still stuck to the mold, apply some more mold release agent and try again.
  • Use a release tool: For more stubborn molds, a release tool can be used to gently pry the resin from the mold. Be sure to use a tool that won’t scratch or damage the mold.

Best Resin for Molds:

When it comes to resin casting, choosing the right type of resin is crucial for achieving the desired results. Here are some of the best types of resin to use for different types of molds:

Epoxy Resin:

Epoxy resin is a popular choice for resin casting due to its strength and durability. It is ideal for casting jewelry, small figurines, and other small objects.

Polyurethane Resin:

Polyurethane resin is a versatile resin that can be used for a variety of applications, including casting larger objects such as home decor items and furniture.

Polyester Resin:

Polyester resin is another popular choice for casting small objects such as jewelry and ornaments. It is easy to use and dries quickly.

When choosing a resin for your molds, it is important to consider factors such as the size of the object being cast, the complexity of the mold, and the desired level of detail. Some high-quality resins to consider include ArtResin, Resin Obsession, and Alumilite. These resins are known for their clarity, durability, and ease of use.

Making Your Own Molds:

Resin casting can be even more rewarding when you make your own molds. Creating custom molds for epoxy allows you to make unique and one-of-a-kind resin pieces.

Here are some steps to make your own silicone mold.

Materials and Tools Needed:

  1. Original object to be molded
  2. Silicone mold making rubber
  3. Release agent (such as petroleum jelly)
  4. Mixing cups and stirrers
  5. Rubber gloves
  6. Exacto knife or scissors
  7. Plastic container for the mold

Preparing the Original Object:

Clean the original object thoroughly and apply a release agent such as petroleum jelly. This will make it easier to remove the mold from the object after casting.

Mixing the Silicone Rubber:

Follow the manufacturer’s instructions to mix the silicone mold making rubber. Generally, you will need to mix equal parts of the two components together until they are thoroughly blended.

Pouring the Mold:

Pour the silicone rubber mixture into the plastic container, making sure it covers the original object. Tap the container on a hard surface to release any air bubbles.

Curing Time:

Allow the silicone rubber to cure according to the manufacturer’s instructions. This may take several hours or overnight.

Removing the Mold:

Once the silicone has cured, remove the mold from the container and gently peel it away from the original object. Use an exacto knife or scissors to trim any excess silicone from the mold.

Using the Mold:

Apply a release agent to the mold before using it for resin casting. Follow the instructions for resin casting, and carefully pour the resin into the mold. Allow the resin to cure according to the manufacturer’s instructions before removing it from the mold.

Making your own molds can be a fun and creative way to customize your resin casting projects. With a little practice and patience, you can make unique and intricate molds for all of your resin casting needs.

Care and Maintenance of Molds:

Proper care and maintenance of molds is essential to ensure that they last for a long time and continue to produce quality resin casts.

Here are some tips for caring for your molds:

Clean Your Molds After Each Use:

After you have finished casting resin, it is important to clean your resin molds thoroughly. You can use warm, soapy water or rubbing alcohol to clean your molds. Rinse them well and let them dry completely before storing them.

Store Molds in a Cool, Dry Place:

Epoxy molds should be stored in a place that is free from moisture and direct sunlight. Avoid storing them in areas where they may be exposed to extreme temperatures or humidity.

Use Mold Release:

Mold release helps to extend the life of molds by preventing the resin from sticking to the mold. Before casting, apply mold release to the mold according to the manufacturer’s instructions.

Avoid Using Sharp Tools on Molds:

Sharp tools can scratch and damage molds, which can lead to poor quality casts. Use gentle tools and avoid using anything that could scratch the mold’s surface.

Keep Molds Away from Pets and Children:

Resin Molds should be kept out of reach of pets and children to avoid damage or injury.

By following these tips, you can ensure that your epoxy molds last for a long time and continue to produce high-quality resin casts.


How long does it take for resin to cure in a mold?

The curing time for resin can vary based on the type of resin used and environmental factors such as temperature and humidity. Generally, resin can take anywhere from several hours to a full day to cure completely.

Can I reuse my molds?

Yes, molds can be reused multiple times if they are properly cared for and maintained.

Can I use any type of mold for resin casting?

No, not all molds are suitable for use with resin. It’s important to choose a mold that is made specifically for resin casting to ensure a successful project.

Can I use food molds for resin casting?

It is not recommended to use molds that were designed for food use for resin casting. Food molds may not be made with materials that are safe for use with resin, and could potentially contaminate your resin.

How do I clean my molds after use?

Molds should be cleaned with warm, soapy water and a soft brush or sponge. Avoid using abrasive cleaners or scrubbers that could damage the surface of the mold. After cleaning, allow the mold to air dry completely before storing.

Can I use silicone caulk to make my own molds?

While silicone caulk can be used to make molds, it is not recommended as it may not provide the same level of detail and precision as a silicone mold made specifically for resin casting. Additionally, some silicone caulks may not be safe for use with resin.

Can I speed up the curing process for resin in a mold?

While it’s not recommended to rush the curing process for resin, you can speed it up slightly by placing the mold in a warm, dry area or using a heat gun or hair dryer on low heat. However, be careful not to overheat the resin as this can cause it to bubble or warp.


In conclusion, choosing the right mold for epoxy resin casting is crucial for achieving beautiful and successful results. We have discussed various types of molds, their pros and cons, factors to consider when choosing a mold, and tips for using and maintaining molds.

We have also covered making your own epoxy silicone molds and provided recommendations for high-quality resins. By following these guidelines, you can create unique and stunning resin pieces. Remember to experiment with new mold ideas and techniques to take your resin casting to the next level.

Don’t forget to properly clean and store your molds to extend their lifespan.

We hope this article has been helpful and inspires you to explore the exciting world of resin casting.

Nouman Ali

Nouman Ali

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