Does Humidity affect Epoxy Resin?

Does humidity affect epoxy resin? The short answer is, absolutely yes.
If you’re an Epoxy Resin enthusiast, you may have experienced the challenges of working with resin in humid conditions, especially if you live in Australia. Humidity can significantly impact the curing process of any epoxy resin, resulting in undesirable outcomes such as; bubbles, cloudiness, and uneven surfaces, just to name a few. In this blog post, we’ll delve into the different effects of humidity on epoxy resin and provide you with the best tips to avoid potential issues, so you can achieve stunning resin creations, even in the humid Australian weather.

Why Does Humidity Matter?

Epoxy Resin is a type of plastic that undergoes a chemical reaction called curing, where it transforms from a liquid to a solid. This process is exothermic, meaning it generates heat as the 2 parts (Part A and Part B) bond together and the resin hardens. Humidity can affect this curing process by influencing the resin’s viscosity, pot life (the time it takes for the resin to start hardening), and the release of air bubbles.

High levels of humidity can cause the resin and hardener to become thinner and have a shorter pot life. The excess moisture in the air can react with the resin and speed up the curing process. This can result in shorter drying times, however can increase the chances of trapped air bubbles, along with a higher risk of the resin not fully curing, leading to a tacky or soft surface.

When high levels of moisture are introduced to the resin, you may end up with crystallisation or what’s called “Amine Blush” – where the resin appears to have a film or oily finish to the surface. – This then results in loss of clarity. However this can be fixed by sanding back the layer of resin and re-coating ensuring the humidity levels have dropped and temperatures are warmer.  This can commonly occur during the Winter months.

On the other hand, low humidity levels can cause the resin to become thicker and have a longer pot life. The lack of moisture in the air can slow down the curing process, however this can be beneficial by allowing you more time to remove any trapped air bubbles.

Tips for Avoiding Humidity Issues –

1. Choose the Right Time and Location: Ideal conditions would be to work with resin between 20-25 degrees Celsius with humidity levels below 40-60%. Consider working with epoxy resin in a controlled environment with optimal humidity levels. It’s best to avoid working in extreme humidity conditions, such as during rainy or very hot and humid days. Choose a well-ventilated area.
2. Use a Dehumidifier: Depending on the climate in your location, you may need to consider using a dehumidifier to regulate the humidity in your working space. A dehumidifier can help reduce excess moisture in the air.
3. Pre-condition Your Materials: Before starting your resin project, it’s important to pre-condition your materials. This includes the resin, hardener, and any additives (including moulds) to the temperature and humidity of your working environment. This can help minimise the impact of humidity on the resin’s curing process.
4. Mix Properly and Avoid Over-Mixing: Follow the Manufacturer’s instructions provided for correct mixing ratios and techniques – every epoxy resin brand will vary. Avoid over-mixing the resin, as excessive stirring can introduce more air bubbles and speed up your curing, which can then potentially affect the curing process.
5. Use a Heat Gun or Torch: To help release trapped air bubbles in the resin, you can use a heat gun or torch to gently apply heat to the surface of the resin. Be cautious not to hold the heat source too close or for too long in one particular area, as it can cause the resin to overheat and become distorted.
6. Allow for Sufficient Curing Time: Be patient and allow the resin to cure for the manufacturers’ recommended time, taking into account the humidity levels in your environment. Avoid rushing the process, as premature de-moulding or handling can result in damage or surface imperfections.

You will find when working with U RESIN Epoxy Resin systems, that there is a good tolerance for humidity. We have specially formulated our epoxy resin systems for the Australian climate, and have tested our products in all temperatures and levels of humidity. Unfortunately no resin can be 100% perfect, but as long as you can avoid humidity or significant temperature adjustments when working with epoxy you will (or should) have a great finish every time!