Mould Warping & Resin Sticking – What Causes It and How to Prevent It

Introduction

Ever poured a perfect batch of resin—only to demould a warped or stuck mess? Whether you're a beginner or a seasoned artist, mould warping and resin sticking can ruin hours of work.

In this guide, we explain why this happens and how to prevent it when working with Mycast Epoxy Resin and high-quality silicone moulds.

Common Causes of Mould Warping

1. Uneven or Unlevelled Surfaces
   

   • If your workspace isn’t flat, resin pools unevenly, causing bending.
     

   • Fix: Use a bubble level or smartphone app to check your surface before pouring.
     
     

2. High Internal Heat from Resin Reaction
   

   • Large pours or warm rooms can cause silicone moulds to soften and bend.
     

   • Fix: Use Mycast 2:1 (max 240g) or Mycast 3:1 (max 960g) within safe volume limits. Avoid over-pouring.
     
     

3. Thin Silicone Moulds
   

   • Low-quality moulds or very thin walls are more prone to warping.
     

   • Fix: Use thicker, premium silicone moulds—like the ones from The Mould Story—designed for resin casting.

4. Early Demoulding

   • Removing pieces before the resin is rigid causes deformation.

   • Fix: Demould only after the rigid demoulding time:

     • 24 hrs for Mycast 2:1

     • 30 hrs for Mycast 3:1

Why Resin Sticks to Silicone Moulds

1. Uncured or Improperly Mixed Resin
   

• Incorrect ratio or insufficient mixing leads to sticky results.
  

• Fix: Always use a digital scale, stick to Mycast’s 2:1 or 3:1 ratio, and mix for 3–5 minutes thoroughly.
  
  

2. Humidity & Temperature Issues
   

• Cold or humid conditions slow curing, leaving tacky surfaces.
  

• Fix: Work in 25–30°C with 50–60% humidity. Use a hotbox if conditions are bad.
  
  

3. Damaged or Low-Quality Moulds
   

• Over time, moulds lose their non-stick surface.
  

• Fix: Rotate your moulds and replace old ones. Clean thoroughly after each use.
  
  

4. Overuse of Heat Gun or Torch
   

• Overheating near the edges can cause the resin to bond with silicone.
  

• Fix: Use quick, sweeping motions, and never torch the mould walls.
  
  
  

Final Takeaway

Mould warping and resin sticking aren't signs of failure—they’re just technical issues that can be easily prevented. By using Mycast Epoxy Resin with the right moulds, temperatures, and pour sizes, you can ensure your resin projects come out glossy, bubble-free, and beautifully shaped—every single time.