Read your epoxy ratio before you measure.

Match both components before choosing a ratio

An epoxy recipe belongs to a resin-and-hardener pairing. The resin name, a familiar ratio or the speed printed on a hardener is only part of that identity.

Check the exact component names, product version and applicable market instructions. Keep resin first and hardener second when reading the ratios in this guide. “Part A” and “Part B” need their own product definitions.

A kit’s package sizes, a density figure or another product from the same brand cannot supply a missing recipe. Follow the applicable manufacturer instructions for component preparation, measuring, mixing, handling and application.

Choose the ratio that matches the measuring method

Volume ratios compare volumes. Weight ratios compare masses. Because resin and hardener can have different densities, the same numerical ratio need not work for both methods.

The reviewed US WEST SYSTEM 105/205 sheet explicitly separates its volume and weight recipes. The source explorer retains their exact numbers and the printed October 2014 edition, alongside the manufacturer page that links it. Other regional instructions must be checked separately.

When the manufacturer supplies a weight recipe, use it directly. To derive a mass ratio from a volume ratio mathematically would require the exact component densities and applicable conditions; a mixed or cured density is insufficient. Our density and gram-target guide explains the distinction.

Start from the amount you know

A combined target includes resin and hardener. An amount of resin already in the container fixes only the resin side. The arithmetic must preserve that difference.

For a stated resin:hardener ratio R:H, split a combined target T as T × R ÷ (R + H) resin and T × H ÷ (R + H) hardener. With resin A already measured, add A × H ÷ R hardener. Keep the units on the selected basis throughout.

This example uses the manufacturer’s Slow Hardener ratio row. It does not convert an existing physical batch between mass and volume or select a pour size.

Read the scale target for the current step

An ingredient amount tells you how much to add. A cumulative target tells you the reading to reach while previous ingredients remain on the scale. Taring changes the displayed starting point, while the required ingredient amounts stay the same.

Establish the resin-and-hardener recipe before accounting for fillers or other additions as directed. Filler mass is not hardener mass. Use a scale with suitable capacity and resolution for the manufacturer’s permitted batch.

Keep time and batch limits in their test context

Pot life, gel time, working time and cure time describe different observations. A number on a technical sheet needs its temperature, sample mass and application context. It is not automatically your remaining time in a deep container.

The reviewed US 105/205 sheet distinguishes a 100 g pot-life test at 72°F from thin-film working time. The High Performance instructions identify a different gel-time condition. This guide does not rank products by those numbers.

Follow the exact system’s batch-size, temperature, pour-depth and application limits. Changing the hardener amount to change cure speed changes the recipe. A project’s total required quantity does not establish a suitable single mixing batch.

What the instruction review found

The 2026 MixByParts Epoxy Mixing Instructions Review examined 12 selected resin-and-hardener pairings. Ten explicitly state both volume and weight recipes. The other two specify weight and prohibit measuring components by volume.

All ten dual-basis pairings have numerically different resin:hardener ratios after putting each on the same proportional scale. That describes the published recipes in this sample. It is not a measurement of user error, allowable tolerance or product performance.

Explore the exact pairings

Each record keeps the resin and hardener together, with both numerical recipes where established, the source market, edition and relevant limits. Use the source link to check the full applicable instructions.

How we reviewed the instructions

We froze twelve named pairings across five manufacturers before source coding, covering selected coating, laminating and casting systems. This is a convenience sample chosen for instruction-reading examples, rather than a market survey.