How to Mix Epoxy Resin: A Step-by-Step Guide for Beginners
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Quick answer: Measure resin and hardener in the exact ratio on your label (usually 1:1 or 2:1 by volume). Stir slowly for at least 3 minutes, or your label’s time, scraping the sides and bottom. Then pour it into a second clean cup and mix for 1 to 2 more minutes before you pour.
Mixing is the step that decides whether a piece cures hard or stays sticky, and it’s the step beginners rush. I learned to measure and mix resin laminating boats, and I’ve since mixed the Let’s Resin epoxy kit for Christmas ornaments, a clear top coat and a set of coasters. This guide covers only the mixing: what to check first, the ratio, the steps, and how to tell it’s ready.
🧰 Recommended Kit for This Project
- Let’s Resin 34 oz Epoxy Resin Kit: the kit I’ve used for my own pours. 1:1 by volume, with cups and stir sticks.
- Nitrile gloves: my kit had none.
- Safety glasses: no eye protection in the box either.
Before you open the bottles
Uncured epoxy can make your skin allergic to it with repeated contact, so wear nitrile gloves and eye protection every time you mix. Work with real cross-ventilation. If you’re indoors without it, mixing a larger batch, using a torch or heat gun, or you can smell the resin, wear a NIOSH-approved half-face respirator with organic-vapor cartridges. The resin PPE guide covers what to buy.
Warm the room. Aim for 70–80°F (21–27°C) and humidity of 60% or lower, then check your label, because makers differ: Let’s Resin asks for 75–85°F. Moisture from damp air or wet tools can turn resin cloudy, so make sure cups, sticks and molds are dry.
Warm cold bottles. If the bottles feel cold, stand them, capped, in warm (not hot) water for about 15 minutes, then dry them before you open them. ArtResin does this for its 32 oz kit. Cold resin is thick and full of tiny bubbles; warm resin mixes more easily. It also cures faster, so you’ll have less working time.
What you need:
- Resin and hardener from the same kit
- Graduated mixing cups (two or three) with clear lines
- A flat wooden or silicone stir stick
- A timer
- Gloves and eye protection
- Paper towels and a shallow tray for leftovers
Not sure how much to mix? Work it out first with the resin calculator.
Check your ratio, and measure by volume
The ratio on your label is the one number you can’t change. Most beginner craft epoxies are 1:1 by volume, and some casting resins are 2:1.
| Ratio | How to measure | Where you’ll see it |
|---|---|---|
| 1:1 by volume | Fill two identical cups to the same line | Most beginner and coating kits |
| 2:1 by volume | Two parts resin to one part hardener | Some casting and deep-pour resins |
Volume isn’t weight. Resin and hardener have different densities, so a 1:1 volume ratio is not 1:1 on a scale (ArtResin). Use graduated cups unless your label gives a weight ratio; if it does, weigh to that number.
Don’t add extra hardener to make it cure faster or harder. It throws off the ratio and leaves the resin soft or sticky (ArtResin).
How to mix epoxy resin, step by step
- Set everything out first. Gloves and glasses on, cups, stick and timer within reach, before you open a bottle.
- Measure Part A. Pour the resin to your line in a graduated cup.
- Measure Part B. Pour the hardener to the matching line for your ratio, then combine the two in your mixing cup.
- Stir slowly for at least 3 minutes, or your label’s time, scraping the sides and bottom as you go. It can look mixed after a minute; keep going. Let’s Resin and ArtResin both ask for at least 3 minutes. Stirring fast whips in air.
- Switch cups (worth the extra minute). Pour the mix into a second clean cup and stir for 1 to 2 more minutes. Resin left on the first cup’s walls may not be fully mixed; ArtResin calls it the number one cause of soft, sticky spots. Resin Obsession suggests the same fresh-cup step if you’re unsure.
- Let it rest. Let’s Resin suggests letting mixed resin sit for 5 minutes so bubbles can rise. Don’t wait much longer: its working time is 40–50 minutes.
- Pour without scraping. Leave the last streaks on the cup wall behind (ArtResin).
Mix in batches you can use. The more resin you mix in one cup, the more heat it makes and the faster it sets: Let’s Resin warns a big batch can “flash cure” in minutes. Warmth speeds it up too; WEST SYSTEM’s rule of thumb is that working time roughly halves for every 18°F (10°C) warmer. For bigger projects, mix several smaller batches.
How to tell it’s mixed
- No streaks or swirls. Lift the stick: the resin should run off evenly, with no clear ribbons that look different from the rest.
- A cloud of tiny bubbles is normal straight after stirring. Most rise while the cup rests.
- Warm is normal. The reaction makes heat, so the cup may feel warm. Too hot to hold, or smoking, is a problem: see what to do when resin gets too hot.
From my bench: On my ornament top coat I mixed 1 oz of each part from the Let’s Resin kit, measured to the same line in the kit’s cups, and stirred with a wooden stick. The cup came out cloudy with fine bubbles, which looked worrying but is normal; most of them rose before I poured. Laminating boats taught me the same lesson with polyester resin: measure exactly, and never “fix” a batch by adding more of one part.
How much to mix, and when to mix more
Use the resin calculator for the amount, then add a little extra: some always stays on the cup and stick.
Check your label’s limit per pour, too. Let’s Resin says not to pour more than 200 ml (about 7 oz) into a casting mold at once, or thinner than 3 mm (about 1/8 in). For deeper molds it recommends layers, 3 to 5 hours apart. If you run short, mix a fresh, correctly measured batch; never top up a cup with extra resin or hardener. Epoxy pouring for beginners covers pouring a second layer.
Mixing mistakes that cause sticky or soft resin
| What you see | Likely mixing cause | Next time |
|---|---|---|
| Soft or sticky all over | Wrong ratio, or a cold room | Measure to the label; keep the room at 70–80°F |
| Sticky patches in an otherwise hard piece | Unmixed resin from the cup walls | Scrape while you stir, not while you pour; switch cups |
| Cloudy or milky | Cold resin, or moisture | Warm the bottles; keep humidity at 60% or lower; dry your tools |
| Lots of tiny bubbles | Stirring fast, or cold resin | Stir slowly; warm the bottles; let the cup rest |
Already have a soft or sticky piece? A cold room slows a cure; if yours was below about 65°F (18°C), move the piece somewhere at 75–80°F for another 24–48 hours before you give up. Then see why is my resin sticky and how to fix resin that didn’t cure. For bubbles after the pour, see how to get bubbles out of resin. Not sure your kit is the right type for your project? See casting vs coating resin.
Most craft epoxies are usable in about 72 hours and reach full hardness in about 7 days; anything that will hold food or drink waits the full 7 days. Check your label, and see how long resin takes to cure.
Cleanup and leftovers
Wipe your stick and tools before the resin sets. If resin gets on your skin, wipe it off, use a waterless hand cleaner (soap and warm water for hardener), then wash with soap and warm water. Never use solvents on skin.
Mixed epoxy left in a cup keeps heating up and can melt the plastic or start a fire. Spread leftovers in a wide, shallow tray, away from anything that can burn, and let them harden (WEST SYSTEM). Never pour resin down the drain (ArtResin). Liquid resin or hardener you won’t use: ask your local solid-waste or environmental agency about household hazardous waste collection (EPA).
Frequently Asked Questions
What ratio do I mix epoxy resin?
Whatever your label says. Most beginner craft epoxies are 1:1 by volume, and some casting resins are 2:1. Don’t adjust it: changing the ratio leaves resin soft or sticky.
Can I measure epoxy resin by weight?
Only with the weight ratio your maker publishes. Resin and hardener have different densities, so equal weights aren’t equal volumes. If your label gives a volume ratio, use graduated cups.
How long should I stir epoxy resin?
At least 3 minutes, or your label’s time, stirring slowly and scraping the sides and bottom. Let’s Resin and ArtResin both ask for 3 minutes. If you’re unsure, pour it into a clean cup and stir for 1 to 2 more minutes.
Can I add more hardener to make resin cure faster?
No. Extra hardener throws off the ratio and leaves the resin soft or sticky. To help a slow cure, keep the room within your label’s range; if you add heat, use a heat lamp or curing box at 85°F or below, never an oven.
Why is my mixed resin warm or cloudy?
Warm is normal: the reaction makes heat, and a bigger batch gets hotter. Too hot to hold, or smoking, is a problem. Cloudy usually means cold resin full of tiny bubbles, or moisture: warm the bottles, stir slowly, keep humidity at 60% or lower and dry your tools.
Sources
- ArtResin: How to mix resin and hardener: equal parts by volume, 3 full minutes, scrape while mixing but not while pouring, extra hardener, weight vs volume
- ArtResin: Why give resin a warm water bath?: capped bottles, about 15 minutes, dry them off; warm resin cures faster
- ArtResin: Does humidity affect epoxy resin?: moisture and wet tools cause cloudy resin
- ArtResin FAQ: never pour resin down the drain
- Let’s Resin: Know more about epoxy resin: 1:1 by volume, stir at least 3 minutes, 75–85°F, 40–50 minutes working time, 200 ml per pour, rest 5 minutes
- Resin Obsession: Super clear resin mixing instructions: a fresh container and 1½–2 more minutes if unsure
- Epoxyworks (WEST SYSTEM): Controlling exotherm: pot life halves for every 18°F warmer; bigger batches set faster
- WEST SYSTEM: Uncontrolled cure: leftover mixed epoxy in a shallow tray
- WEST SYSTEM: Health effects from overexposure to epoxy: skin sensitization
- US EPA: Household hazardous waste
Keep Learning on ResinAffairs.com
Put your mixing skills to work. Here’s where to go next:
- ☕ How to Make Epoxy Resin Coasters → — the classic first project, with a full supply list and troubleshooting.
- 🧩 Best Resin Molds for Beginners → — silicone vs. plastic vs. DIY molds, and which one to buy for each project.
- 🥤 Resin Tumblers for Beginners → — how to coat your first epoxy tumbler on a turner without drips.
- 🩹 Common Resin Problems and How to Fix Them → — fixes for stickiness, bubbles, soft spots and cracks on any resin project.
- 🪣 Epoxy Pouring for Beginners: Step-by-Step → — pour technique, bubble removal, and the mistakes that cause the most redo pours.
- How long does resin take to cure →
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