How to Mix Epoxy Correctly — Step-by-Step Technique
Most epoxy failures — sticky surfaces, soft cures, bubbles, cloudiness — trace back to mixing errors. Getting the mix right requires the correct ratio, the right tools, the right temperature, and a specific mixing motion. This guide covers every element of correct epoxy mixing in the order you need to perform it.
Calculate the exact amounts of resin and hardener needed for your project before you mix.
Use the Mix Ratio Calculator →Step 1 — Verify the Mix Ratio
Before measuring anything, confirm the mix ratio from your product's technical data sheet (TDS). Common ratios by volume:
| Ratio | Common use | Example: total 16 oz |
|---|---|---|
| 1:1 | Most tabletop and countertop coatings | 8 oz resin + 8 oz hardener |
| 2:1 | Many casting resins, structural epoxies | 10.7 oz resin + 5.3 oz hardener |
| 3:1 | Some casting and coating systems | 12 oz resin + 4 oz hardener |
| 4:1 | Some marine and structural epoxies | 12.8 oz resin + 3.2 oz hardener |
Use the mix ratio calculator to get exact amounts by volume or weight for your specific project size.
Step 2 — Gather the Right Tools
What you need
- Graduated mixing cups — plastic cups with volume markings. Avoid wax-coated paper cups (wax contaminates epoxy)
- Two mixing sticks — flat wooden or plastic sticks, not round dowels
- Digital scale — for products measured by weight (always check your TDS)
- Nitrile gloves — not latex (latex can inhibit some hardeners)
- Safety glasses
Two-cup method: Mix in one cup, then pour the mix into a second clean cup and stir for 30 more seconds. This captures unmixed material stuck to the walls and bottom of the first cup — a major source of soft spots.
Step 3 — Prepare Temperature
Both components should be at 72–80°F (22–27°C) before mixing. Cold resin is thicker, mixes unevenly, and holds air bubbles. If your bottles have been stored in a cool space:
- Set the sealed bottles in a warm water bath (not above 90°F) for 10–15 minutes
- Wipe the bottles dry before opening
- Ensure the room is also 70°F or warmer
Step 4 — Measure Accurately
- Pour Part A (resin) into a graduated mixing cup to the exact target volume or weight
- Add Part B (hardener) to reach the correct combined ratio — do not eyeball
- If measuring by weight, zero the scale with the empty cup before adding each component
Do not estimate by sight. Being off by even 10% from the correct ratio will produce a significantly under-cured result. See: what happens if epoxy ratio is wrong.
Step 5 — Mix with the Correct Motion
This is the step most people do wrong. The goal is thorough incorporation without air introduction.
- Stir slowly using a figure-8 or folding motion — never a whipping or circular swirl
- Scrape the bottom of the cup continuously — unmixed material accumulates there
- Scrape the sides of the cup from top to bottom every 30 seconds
- Mix for a minimum of 3–5 minutes for small batches; 5–7 minutes for batches over 32 oz
- Transfer to a second cup and stir for 30 more seconds
How to know it's mixed: The liquid should look completely clear (for clear epoxies) with no streaks, swirls, or cloudiness. Streaks indicate incompletely mixed components — keep going.
Common Mistakes to Avoid
| Mistake | Consequence |
|---|---|
| Wrong ratio (even slightly off) | Soft, sticky, or flexible cure |
| Under-mixing (under 3 minutes) | Soft spots, streaks, incomplete cure |
| Mixing too fast (high-speed drill) | Foam and micro-bubbles throughout |
| Not scraping cup sides/bottom | Unmixed hardener pockets in cured pour |
| Cold resin (under 65°F) | Thick mix, slow cure, bubble retention |
| Wax-coated paper cups | Wax contamination, tacky surface |
| Mixing too large a batch | Pot life exceeded, heat buildup, cracking |
Frequently Asked Questions
How long should you mix epoxy resin?
Minimum 3–5 minutes for batches under 32 oz, and 5–7 minutes for larger batches. Use the two-cup method — transfer to a second cup and stir 30 more seconds — to incorporate material stuck to the original cup walls.
What is the correct mixing ratio for epoxy?
It depends on the product. Common ratios are 1:1, 2:1, and 3:1 (resin to hardener by volume). Always check your product's TDS — using a 1:1 product at 2:1 produces sticky, under-cured epoxy. Use the mix ratio calculator to confirm your amounts.
Can you mix epoxy with a drill?
Yes, but keep the drill below 400 RPM. High-speed mixing whips air into the resin and causes micro-bubbles. For batches under 16 oz, hand mixing is usually better — less air introduced, easier to control.