Step-by Step Guide: Measuring and Mixing Epoxy Resins
Measuring and mixing epoxy resins accurately and safely is an essential skill for any resin user that wants to stay healthy and have great results with their project.
In this tutorial, we will show you two recommended techniques for measuring and mixing epoxy resins by weight or volume.
Mixing Epoxy Resins 101 – Choose Your Resin
For this demonstration, we are using our Super SAP CLR epoxy resin system from Entropy Resins. All of their retail formulas are two-part epoxy systems made up of a resin (Part A) and a hardener (Part B).
As with all epoxy resins, our systems are designed to work in a specific mix ratio between the two parts. Our CLR epoxy resin with CLF Fast Hardener works in a 100:47 mix ratio by weight or a 2:1 volume ratio.
Measuring and Mixing Epoxy Resins Safely
Part of beginning any project is always making sure you have the proper tools and safety equipment for using and handling epoxy resins, including the following:
- Eye Protection
- Disposable Latex or Reusable Rubber Gloves
- Clean Mixing Cups (If you’re using recycled materials avoid anything that held fats/oils, like butter or margarine containers.)
- Clean Mixing Sticks
- Small Kitchen-style Digital Scale (0.01 Ounce) or Disposable Graduated Cylinders (Measuring Cup)
Measuring Epoxy by Weight Using a Digital Scale
Begin by powering on your scale and choosing your unit of measurement. Most scales measure in either grams or ounces. Ensure that you have chosen a unit of measure that can help you determine 0.1 Ounces or Grams. If the quantity is too small for the scale to give an accurate measurement it will be hard to get consistent mixtures, we recommend a minimum 1.47 Ounce mixture (1 Ounce resin, .47 Ounces hardener).
Place your mixing cup on the scale and reset the scale to zero by pressing the Tare or Zero Scale button.
Pour your epoxy first and note the amount poured. (Example: 10 Ounces)
Calculate the amount of hardener needed based on that amount of epoxy resin that you poured.
Example: In this case, we used 10 Ounces of epoxy, that would require 4.7 Ounces of Hardener, this will give us a total combined weight of 14.7 Ounces of mixed materials.
Pour in your hardener, directly from the bottle to the mixtures. If your scale resets due to inactivity before you have a chance to complete the mixture you’ll only need to measure out the hardener.
Epoxy and hardener have different densities which means that epoxy weighs more than the hardener, we recommend keeping a chart for quick reference to ensure that you make accurate mixtures. See below for the Entropy Quick Guide.
- If you pour slightly above your target weight, don’t worry. As long as you are within the 5% maximum error margin specified for this resin system, you’re fine.
Note: Adding more hardener will not kick the epoxy faster, it will cause excessive blushing and negatively affect cured strengths and curing times. Only use the manufacturer's recommended mix ratios.
Note: Make sure to double check the maximum margin of error on your system.
Measuring Epoxy by Volume
You can also measure your epoxy resin by volume, just make sure you have mixing cups with well-marked graduations.
- Determine as close as possible the amount of mixed material that the application requires. If you require more epoxy resin, you can always mix a second batch to finish off the job. Resin is an expensive input for any application so try and keep wastage to a minimum.
Begin by pouring the epoxy amount your mixture requires into the graduated measuring cup.
When pouring, be sure that the bottom of the curved liquid surface, called the meniscus, meets the line that you're pouring to. Warmer epoxy will lay flat, if necessary give it a moment to settle before calculating the amount of hardener required.
In this image, you can see the meniscus is the bottom of the curved liquid line created by the liquid surface.
Next, pour in the required hardener to complete the mixture. Most of our ambient cure wet lay-up epoxy systems from Entropy are 2:1 by volume, so this means we will be pouring two parts epoxy to one part hardener. Always verify using the manufacturer's directions printed on the bottle.
Example: Our total material requirement is approximately 8-10 ounces of mixed epoxy/hardener. In this case, we’ll use 6 ounces of epoxy and 3 ounces of hardener, measured by volume, for a total of 9 ounces of mixed material. If more is required to complete the job mix up a batch of 1.5 (minimum recommended mixture).
Mixing Epoxy Resins
After the two parts are poured at the correct ratio, mix them together thoroughly for a full 2 - 3 minutes with a mixing stick, mix longer for larger quantities.
Be sure to scrape the sides, corners, and bottom of the container several times during mixing. This will ensure that all the hardener is thoroughly mixed with the epoxy and should prevent the resin from having an improper cure.
Make sure to scrape both sides of the mixing cup also. If the mixture doesn't have a single consistency (streaks remain) continue mixing until fully blended.
- Start pouring or applying the epoxy immediately, the larger the quantity of mixed material in the cup the faster the Pot-life and working time.
Here’s a helpful video to demonstrate:
Now you are ready to use your resin. Remember to check the safe use guides, safe handling information and technical data sheets that come with your epoxy system before mixing.
Now that you know all about mixing epoxy resins check out our 15 Tips and Tricks for the Perfect Epoxy Resin Mix or What you need to know about resins and solvent.