Versatile and easy to apply, epoxy resin helps repair, fix, bond, and create a wide range of projects. Whether you want to make furniture or jewelry, epoxy resin allows you to express your creativity—provided you know how to use it properly. Epoxy resin is made up of a base resin and a hardener. To achieve a successful result, it is essential to respect the correct mixing ratio between these two components. Do you have a project in mind where epoxy resin would be ideal? Follow our guide to get it right every time!

Step 1: Determine the amount of resin you need

This step is essential if you want to use enough resin without wasting any. To do this, you’ll need to carry out a few very simple calculations.

If you are using a casting resin for a mold, you must first calculate the volume you want to fill. The calculation is straightforward:

  • For a square or rectangular mold: multiply the length by the width by the height.

  • For a circular mold: π × radius² × height.

Length (cm) × width (cm) × height (cm) = volume in cubic centimeters (cm³).

Once you have the volume, you’ll need to calculate how many liters are required to fill your mold. The formula is:

Volume in cubic centimeters ÷ 1000 = volume in liters.

Be sure to add a 3% margin to compensate for any potential loss.

If you are simply applying the resin in a thin layer, you will need to determine the layer thickness in advance in order to accurately estimate the required amount of resin.

Step 2: Measure your epoxy resin precisely

This is probably the most crucial step for a successful mix: read the instructions on your epoxy resin packaging. Not all epoxy resins are the same, and the mixing ratio between the base resin and the hardener can vary from one system to another.

The ratio indicates the mixing proportion between the resin and the hardener. You need a precise amount of each to trigger the correct chemical reaction.

If you do not respect the recommended ratio, the resin may heat up too quickly (which can be dangerous) or may not cure at all. This is why it is essential to strictly follow the manufacturer’s recommendations.

The ratio is usually indicated by two numbers separated by a slash or a colon. The first number represents the amount of resin, and the second represents the amount of hardener.
For example:

  • 1:1 ml means you must mix equal amounts of resin and hardener.

  • 2:1 ml means twice as much resin as hardener (e.g., Resin: 100 ml + Hardener: 50 ml).

When the ratio is expressed in milliliters, this is known as volumetric measurement. To measure each component, you will need a graduated mixing cup.

However, the ratio can also be expressed in grams, which is called weight-based measurement.
For example, with a ratio of 100:42, for 100 g of resin, you will need 42 g of hardener.

100 g (resin) × 1.42 (mixing ratio = 1 + 42/100) = 142 g total mixture.

In this case, you will need a digital scale to measure each quantity accurately.

Step 3: Mix the epoxy resin

Once your calculations are done and your measurements are accurate, it’s time to mix. Carefully mix the resin and hardener using a wooden stick or similar tool for at least 3 minutes.

Take your time and work carefully. Don’t forget to scrape the sides and walls of your container, loosening any resin that sticks there during mixing. Do the same for the bottom of the container.

This step is critical. Even if your measurements are correct, poor mixing will prevent proper curing. Without a complete chemical reaction between the components, the resin will not harden and your project will fail.

That’s it—you now know everything you need to successfully mix your resin and hardener. It’s not complicated: simply respect the recommended ratio and perform the necessary calculations based on your specific mixing system.