How to Stir Polyester Resin for a Consistent Reaction

← Back to How to catalyse polyester resin?

Stir Thoroughly for at Least Two Minutes to Ensure an Even Reaction

When preparing polyester resin, stirring thoroughly is a key step that helps ensure proper curing and a successful repair. Taking just two minutes for this process can make a significant difference to your project’s strength and finish.

The Importance of Thorough Stirring

When the hardener is added to polyester resin—typically at around 3% of the total volume—these two components must be blended uniformly for the chemical curing process to begin correctly. Stirring for at least two minutes helps ensure the catalyst is fully distributed, preventing soft or tacky spots that could weaken your repair.

Use a clean mixing container and stir stick.
Scrape the sides and bottom frequently during mixing.
Mix briskly but avoid creating excessive air bubbles.

Step-by-Step: Mixing Polyester Resin and Hardener

Start by measuring out the resin and the correct amount of hardener as directed, such as in the Resin Fibreglass Repair Kit. Pour the hardener into the resin, and stir continuously for at least two minutes. Make sure you reach all corners of your mixing container to achieve total blend.

After mixing, you’ll have a limited working time before the resin begins to set. Plan your application and have your materials ready in advance for best results.

When Thorough Stirring Matters Most

Consistent stirring is especially crucial for projects where strength and waterproofing are essential, such as repairs to boats, swimming pools, tanks, or rigid plastics and metals. Skipping this careful step could compromise both the adhesion and durability of your finished repair.

Related guides

A good stir might seem simple, but it is fundamental to any polyester resin repair. For more insights on best mixing practices and the entire repair process, return to our guide on how to catalyse polyester resin.