Why Is My Resin Still Sticky? 7 Reasons and Their Fixes

Introduction

You've measured, mixed, and poured—but hours (or even days) later, your resin is still sticky, soft, or rubbery. This is one of the most common issues resin artists face, especially when learning.

The good news? Sticky resin is preventable—and sometimes fixable.

Here are the top 7 reasons your resin didn’t cure properly and how to avoid or correct the issue when using Mycast Epoxy Resin.

1. Incorrect Mixing Ratio

What Happens: If you don’t use the correct 2:1 or 3:1 ratio by weight, the resin and hardener can’t bond properly.
Fix: Always use a digital scale and follow the correct ratio based on your Mycast variant.

• 2:1 Casting/Coating → 100g resin : 50g hardener
  

• 3:1 Casting → 100g resin : 33.3g hardener

2. Incomplete Mixing

What Happens: If you don’t mix thoroughly, unmixed resin gets trapped and stays sticky.
Fix: Mix for 3–5 minutes, scraping the sides and bottom of the cup. Stir slowly to reduce bubbles.

3. Low Room Temperature

What Happens: Cold environments slow the chemical reaction, delaying or preventing curing.
Fix: Work in a space around 25–30°C. If it’s too cold, use a DIY hotbox or place the mould in a warmer room.

4. Too Much Pigment or the Wrong Type

What Happens: Excessive pigment or using water-based colorants disrupts curing.
Fix: Use resin-safe pigments like mica or oil-based colors, and limit pigment to 5–7% of resin weight.

5. You Demoulded Too Early

What Happens: Resin may feel hard on top but is still soft inside.
Fix: Wait for the rigid demoulding time:

• Mycast 2:1 → 24 hours
  

• Mycast 3:1 → 30 hours
  Then allow full internal cure (30–36 hours) before sanding or packing.

6. You Left Resin Sitting in the Cup Too Long

What Happens: Resin heats up in large volumes and can flash cure, leaving the poured layer uncured.
Fix: Pour within the working window:

• ~35 mins for 2:1
  

• ~1.5 hours for 3:1
   Use smaller cups for large mixes to avoid overheating.
  

7. Dirty Tools or Contaminated Moulds

What Happens: Residues from oil, dust, or previous pours can prevent curing.
Fix: Clean your tools and moulds with IPA (isopropyl alcohol) or mild soap. Avoid moisture.

How to Fix Sticky Resin (If It’s Already Poured)

• If only the surface is sticky:
   Sand off the tacky layer and recoat with a thin layer of fresh Mycast resin.
  

• If the entire piece is soft or gummy:
   Remove it and discard. Sticky resin is a result of a failed chemical reaction—it won’t fully harden.
  

Final Takeaway

Sticky resin isn't a mystery—it's usually a small mistake in measurement, mixing, or environment. With Mycast’s consistent performance, VOC-free formula, and clear mixing instructions, you can confidently pour with fewer surprises and professional results.