The Science of Curing Resin — and What the Gold Coast Weather Taught Me

How curing resin actually works

Most people assume resin works the way paint or glue does — you pour it, walk away, and come back to something set. It isn't that simple. Curing resin happens through a chemical reaction between two parts, resin and hardener, and that reaction is exothermic, it gives off heat as it happens, rather than needing heat added to it. The resin and hardener molecules are bonding together into a new, solid structure, and that bonding process releases energy as it goes, which you can sometimes feel as warmth if you touch the side of a curing piece. It's a reaction, not a drying process, and reactions are sensitive to their environment in a way most people don't expect.

Why temperature runs the whole show

Because curing is a chemical reaction, the temperature around the resin speeds it up or slows it down, sometimes dramatically. I found this out properly this past winter. Gold Coast nights were sitting around 20°C or below, mild by most standards, mine included until I lived it, and it added several hours onto my cure time. A difference of just a few degrees was enough to shorten that by a surprising amount.

Summer brings the opposite problem. Resin can't be allowed to run too hot either, and without air conditioning running constantly, it's just as easy to overheat a cure in January as it is to under-heat one in July.

The swirl I couldn't explain at first

Something I noticed early on: a strange swirl effect would sometimes show up in my top flood coat layer specifically. Not cloudy, still clear to see through, just an odd, visible pattern sitting in that top layer. After some digging, the most likely explanation is that in cold conditions, part of the resin component can start to crystallise slightly before it's fully cured, which shows up as swirls or waves. It's worth knowing about a related, more common issue too, amine blush, a hazy or cloudy film that can form on a curing surface, usually tied to the same temperature and humidity swings.

My fix: a resin box

If you can already hold a steady temperature across your whole studio or workshop, you probably don't need this at all. I can't, so I built what I call my resin box instead, an idea I came across from other resin artists doing something similar and adapted for my own studio. It's a styrofoam insulated box I can drop either an ice pack or a heating pad into depending on the season, with a temperature sensor that sends an alert to my phone if it drifts outside the range I want. Controlling a small, enclosed space like this is a lot cheaper than heating or cooling an entire room, and for a small business watching costs, that difference matters. Either way, it's not a set-and-forget process. Most people assume you pour resin, check back in six to eight hours, and find it set. That's not how it actually works, at least not reliably. It's a process of constant checking.

What I've learned about base layers, viscosity, and bubbles

On a larger piece, it's crucial to let the base layer get properly tacky-hard before building on it. I once poured the second layer over it, thinking it was tacky enough. It wasn't nearly hard enough. The flowers I placed on top started to rise almost straight away, and pushing them back down just dragged more bubbles in with them. One bad judgement call on timing turned into a much bigger clean-up job than it needed to be.

Since then I've also found the resin's viscosity matters for the base layer specifically. A 2:1 mix is thicker and tackier than a 3:1, and it sets quicker, which holds flowers in place better on that first layer. The middle layers are still doing exactly the job they're meant to, especially on a deep pour — each layer simply suits a different purpose. I use the same clear resin on the bottom and flood coats, the thicker mix earns its keep at the bottom and clarity at the top.

That base layer mistake also taught me how genuinely difficult bubbles are to shift once a piece has been left overnight. So the real goal before walking away from any layer is getting rid of as many surface bubbles as possible while the resin's still workable. A few small ones here and there is normal, honestly almost impossible to avoid completely, but chasing the big ones down before you leave it saves a lot of grief the next morning.

Bubbles are the age-old problem in resin work more generally, and prevention starts well before you pour. I auto-mix on a slow speed for a good five minutes, scraping the sides of the cup as I go, then pour at the side of the mould rather than in the middle or directly onto the flowers. From there it's a matter of checking constantly rather than walking away. Bubbles sitting on the surface are easy to catch and remove while the resin's still workable. Even once a layer has set, a bubble that's not too deep can often still be fixed, poke it to release the trapped air pocket, then let the heat from the next layer you pour help smooth it back out.

The mould matters more than people expect

Getting the mould right is another thing that catches people out. I learned this the hard way with a cheaper mould, one that even had wooden supports around the sides, and it still bent under the pressure once the resin was in. Since then I've moved to properly reusable moulds that don't warp no matter how many pours they go through. HDPE moulds are another solid option, though they're a fair bit harder to get your piece out of once it's set.

Why I'm sharing this

Resin is still a newer part of what I do, and sharing what I've learned will help someone through the same guesswork, whether that's a bride curious about the process or someone starting out on their own resin journey.

If all this feels like a lot, let someone do it for you. Check out our resin options, or get in touch.