Why Are My Resin Keychains Breaking?

Resin keychains are popular for their versatility, durability, and unique aesthetic appeal. However, it can be frustrating when your carefully crafted keychains start breaking or cracking. Understanding the common reasons behind these issues and learning how to avoid them can save you time, money, and effort. This comprehensive guide will delve into the possible causes of breaking resin custom keychains and provide you with tips and best practices to create long-lasting, durable pieces.

Understanding Resin

Before we dive into the causes of breaking resin keychains, it's essential to understand what resin is and how it works. Resin is a synthetic polymer that starts as a liquid and hardens over time, creating a solid, plastic-like material. The two main types of resin used in crafting are epoxy resin and polyester resin. Each has its own properties, advantages, and drawbacks.

Epoxy Resin

Epoxy resin is favored for its ease of use, minimal odor, and clear finish. It's mixed in a specific ratio with a hardener, which triggers a chemical reaction, causing it to cure and harden. Epoxy resin is generally more flexible and less brittle than polyester resin, making it a popular choice for keychains and other small crafts.

Polyester Resin

Polyester resin is often used in more industrial applications due to its strength and durability. It cures faster than epoxy resin and is more resistant to UV light. However, it has a stronger odor and can be more challenging to work with. It tends to be more brittle, which can lead to breaking if not used correctly.

Common Causes of Breaking Resin Keychains

Several factors can contribute to the breaking or cracking of resin keychains. Understanding these causes will help you take the necessary steps to prevent them.

  1. Incorrect Mixing Ratios

One of the most common causes of resin keychains breaking is incorrect mixing ratios. Both epoxy and polyester resins require precise mixing with their respective hardeners. If the ratio is off, the resin may not cure properly, leading to weak or brittle keychains.

  1. Inadequate Curing Time

Resin requires adequate curing time to reach its full strength. Rushing the curing process or exposing the resin to fluctuating temperatures can lead to incomplete curing, making the keychain more susceptible to breaking.

  1. Air Bubbles

Air bubbles trapped within the resin can create weak points in your keychains. These bubbles can occur during mixing or pouring. If not addressed, they can cause structural weaknesses that lead to cracking or breaking.

  1. Overloading with Additives

While adding pigments, glitter, or other embellishments can enhance the appearance of your resin keychains, overloading the resin with too many additives can compromise its structural integrity. Ensure that you maintain a balance to avoid weakening the resin.

  1. Inadequate Mold Preparation

The quality of your molds can significantly impact the durability of your resin keychains. Using damaged or poorly prepared molds can result in uneven surfaces, weak spots, or difficulty in demolding, all of which can lead to breakage.

  1. Environmental Factors

Exposure to extreme temperatures, UV light, or moisture can affect the durability of resin keychains. For example, leaving a resin keychain in a hot car or direct sunlight for extended periods can cause it to warp or crack.

  1. Physical Stress

Resin keychains, while durable, are not indestructible. Subjecting them to excessive physical stress, such as dropping them from significant heights or applying too much pressure, can cause them to break.

Tips for Creating Durable Resin Keychains

Now that we’ve identified the common causes of breaking resin keychains, let’s explore some best practices to ensure your keychains are robust and long-lasting.

  1. Accurate Measuring and Mixing

Always measure your resin and hardener accurately according to the manufacturer’s instructions. Use a digital scale for precise measurements and mix thoroughly to ensure a consistent blend. Improper mixing can lead to soft spots or brittleness.

  1. Allow Adequate Curing Time

Patience is key when working with resin. Allow your keychains to cure fully according to the recommended time, typically 24-72 hours. Avoid touching or disturbing the resin during this period to ensure a strong cure.

  1. Remove Air Bubbles

To prevent air bubbles, mix the resin slowly and gently. Use a heat gun or a torch to pass over the surface of the resin after pouring, which will help release trapped bubbles. Alternatively, you can use a pressure pot to eliminate bubbles during the curing process.

  1. Balance Additives

When adding pigments, glitter, or other embellishments, do so sparingly. Too many additives can compromise the resin’s strength. Mix them thoroughly and evenly to maintain the structural integrity of your keychain.

  1. Prepare Molds Properly

Ensure your molds are clean, dry, and in good condition before pouring the resin. Silicone molds are generally the best choice for resin keychains as they allow for easy demolding and create a smooth finish. Apply a mold release agent if necessary to prevent sticking.

  1. Protect from Environmental Factors

Store your resin keychains in a cool, dry place away from direct sunlight and extreme temperatures. Consider using UV-resistant resin to minimize the effects of sun exposure. If your keychains will be used in harsh environments, consider coating them with a protective sealant.

  1. Minimize Physical Stress

Handle your resin keychains with care. Avoid dropping them or subjecting them to excessive pressure. If you’re making keychains that will be attached to items frequently handled, like keys, ensure they’re thick and robust enough to withstand daily use.

  1. Test Different Resin Types

If you’re consistently having issues with breaking keychains, experiment with different types of resin. Some resins are formulated specifically for durability and may better suit your needs. Epoxy resins tend to be more flexible and forgiving, while polyester resins offer greater strength but can be more brittle.


Creating durable resin keychains requires attention to detail, patience, and adherence to best practices. By understanding the common causes of breakage and implementing the tips provided in this guide, you can significantly reduce the likelihood of your resin keychains breaking. Remember to measure and mix accurately, allow sufficient curing time, and handle your keychains with care. With practice and perseverance, you’ll be able to create beautiful, long-lasting resin keychains that withstand the test of time.