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If your polyester resin turns out sticky, soft, or unexpectedly brittle, it can undermine the quality of your repair. Understanding why these problems occur helps ensure your next project cures correctly.
Common Reasons for Sticky or Brittle Resin
Issues like a persistently wet surface or brittleness are often tied to two main factors: an incorrect catalyst ratio and incomplete mixing. Using too little hardener (catalyst) can leave the resin soft or tacky, while too much may cause it to become brittle and prone to cracking. Thorough and even mixing ensures the catalyst is distributed throughout the resin for consistent curing.
How to Prevent Curing Issues
- Measure the catalyst carefully: Follow the manufacturer’s recommended ratio, such as the 3% included in the Resin Fibreglass Repair Kit. Too much or too little can compromise results.
- Mix thoroughly: Blend resin and catalyst together in a clean container, taking care to scrape sides and bottom.
- Work with clean materials: Make sure surfaces and tools are clean, as contaminants can upset proper curing.
When This Matters Most
Proper curing is essential for repairs that demand strength and durability, such as boat hulls, swimming pools, or pressure pipes. In these cases, improper resin setting can mean failed seals or structural weaknesses—making careful dosing and mixing crucial every time.
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Ensuring your polyester resin cures as intended begins with careful measurement and mixing. For more advice on accurate dosing, explore our main guide on how to dose polyester resin catalyst.