How to Mix Epoxy Resin Correctly (Step by Step)
If I had to bet on why a beginner’s piece came out wrong, I’d put my money on the mix before I’d blame anything else. Bubbles, sticky spots, soft patches, cloudiness — a huge share of them start in the cup, in the ninety seconds most people rush through. Mixing looks like the boring part. It’s actually the whole game.
Here’s how I do it, in order, with the reasons behind each step — because once you understand why, you stop cutting the corners that bite you.
First, understand what mixing actually does
Epoxy is two chemicals that only become solid plastic when every molecule of resin meets its share of hardener. Stirring isn’t “blending a color.” You’re physically introducing two liquids to each other so the reaction can complete everywhere, not just in most of the cup.
Miss a pocket and that pocket never cures. That’s the mental model: you’re not mixing paint, you’re making sure no part of the batch gets left out of the reaction.
Warm the bottles, then measure like it counts
Cold resin is thick and gluey, and thick resin both traps air and resists mixing. Ten to fifteen minutes with the closed bottles standing in a bowl of warm water (around 100°F / 38°C) thins everything out and makes the whole job easier. I do this every pour now, winter or not.
Then measure precisely — this is the step that quietly decides everything. Use graduated cups for volume-based resins, or a digital scale for weight-based ones, and follow your specific bottle, because the ratio rules differ more than people expect. “Eyeballing it” is the number one cause of resin that never fully hardens.
Combine, then scrape like you mean it
Pour both parts into one clean mixing cup. Now the part everyone underdoes: scrape. Run your stick around the sides and flat across the bottom of the cup, then up the walls, over and over. Resin clings to the cup, and whatever stays stuck to the wall is hardener (or resin) that never made it into the mix — and it shows up later as a tacky ring or a soft streak.
I learned this the annoying way. Early on I had a batch where the very top cured glassy but the bottom edge against the cup stayed gummy for days. I’d stirred plenty — I just hadn’t scraped. Different motion entirely.
Stir slow, and stir long enough
Slow, deliberate circles. Not whisking, not folding — think stirring honey into tea. Fast stirring whips in air and gives you a bubble problem on top of everything else.
Time it. Three minutes is a fair minimum for a small jewelry batch; bigger batches need longer. It feels like forever standing there, and that’s exactly why people quit at ninety seconds. Set a timer so you’re not guessing.
How to know it’s actually mixed
Here’s the tell most tutorials skip: watch for the schlieren — those wavy, oily-looking streaks swirling in the liquid, like heat shimmer over pavement. While you can see them, the two parts aren’t fully combined. Keep going. When the whole cup turns completely clear and uniform with no streaks at all, that’s done. Not before.
Honestly, this single visual cue fixed more of my early failures than any other tip. Once you’ve seen the streaks vanish, you can’t unsee them.
The trick that saves the most batches: double-cup
When you think you’re done, pour the mixed resin into a second clean cup and stir for another thirty seconds. Any unmixed resin hiding on the walls of the first cup gets left behind there instead of going into your mold.
It sounds fussy. It’s one extra cup. But it’s the closest thing to insurance against soft spots that I know, and it’s what I do for anything I’m selling.
A couple of habits worth keeping
Mind your working time — once it’s mixed, the clock starts, and most resins give you 20–45 minutes before they thicken too far to pour cleanly. And keep your tools consistent: flat wooden sticks (round coffee stirrers don’t scrape corners well), straight-sided graduated cups, nothing damp, since water in the cup hazes the resin.
If you nail the mix, most of the other resin problems simply don’t show up. It really is that central.
Browse my handmade silicone molds for your next pour.
What’s been going wrong for you — tacky spots, bubbles, soft patches? Tell me how you’ve been mixing and I can usually point to the step that’s slipping.
— Nikolai