How to make resin art
Buy the right resin for the depth you are pouring, weigh both parts rather than eyeballing them, and leave it alone once it is poured. Almost every first-batch failure is one of those three.
Pick the system by depth first — a coating epoxy for anything up to 1/8 in in one go, a casting epoxy for pours up to 2 in. Weigh the resin and hardener rather than measuring by eye, stir slowly for three full minutes scraping the sides and the stick, pour, pass a torch over the surface to release the bubbles, then leave it completely alone in a warm dry room overnight.
Resin art is two liquids that do nothing at all until they meet each other, and then do something irreversible. Epoxy is a resin and a hardener that react in fixed proportion to build one solid piece of plastic — not a glue that dries, not a varnish that evaporates, but a chemical reaction with a beginning and an end. That is why there is no undo, no thinning it down and no adding a bit more of something later.
It is also why the single most useful thing a beginner can know has nothing to do with technique. There are three products sold under the word "resin" and they are not interchangeable: a coating epoxy is meant to be poured 1/8 in at a time, a casting epoxy goes to 2 in in one lift, and UV resin sets under a lamp in layers of 1–3 mm. Buy the wrong one for your project and no amount of care will save it.
Everything below is worked out from the same figures the epoxy calculator runs on, so the numbers on this page and the numbers it gives you cannot disagree. If you already know what you are making, start there — it will tell you what to mix, how to split it and how many pours it takes.
What a first project actually takes
Volumes include 10% for what stays in the cup and on the stick, which is not padding — a coating epoxy gives you 20 minutes of working time, so running short halfway through a pour leaves a line you cannot sand out. The resin and hardener columns use each system's own ratio: 1:1 for table top, 2:1 for deep pour.
Which resin to buy first
The glossy coating one. Built to be poured thin over a surface and self-level into a hard, clear film — bar tops, counters, artwork, tumblers. It is fast, and the speed is the point: a coat is dust-free in a few hours instead of a few days. That figure is the most you may pour in one coat. Build thickness with several, letting each firm up first. Start here if you are coating something flat — a board, a panel, a tumbler.
The slow one, and the reason river tables are possible at all. Formulated to react gently enough that a two-inch mass can shed its own heat, which also means a working time measured in hours and a cure measured in days. Thinner, so it releases bubbles on its own. Start here if you are filling a mold rather than covering a surface — coasters, paperweights, anything with a shape of its own.
A different product wearing the same word. One part, no hardener, no measuring — it stays liquid in the bottle indefinitely and sets in under a minute beneath a 365 or 405 nm lamp. Wonderful for tiny work and useless for anything thicker than a coin. The layer limit is optical rather than thermal: the resin absorbs the light that cures it, so a thick pour skins on top and stays liquid underneath permanently. Wonderful for pendants and charms, wrong for anything the size of a coaster.
What decides whether it works
Epoxy cures by a reaction that gives off heat, and the heat speeds the reaction up. In a thin film that warmth escapes into the room; in a deep mass it cannot, so the pour climbs to a temperature it was never designed to reach — it cracks, yellows, smokes, distorts the mold and can scorch what it is standing on. Table top / coating epoxy stops at 1/8 in per coat and deep pour / casting epoxy goes to 2 in, roughly a tenfold difference. This is the one number in this craft where being over is a hazard rather than a disappointment.
The ratio is not a recipe you can lean on. Epoxy and hardener react in fixed proportion, so anything left over after the reaction has finished has nothing to bond to and simply stays in the piece as a soft, sticky contaminant. Extra hardener does not speed the cure up and extra resin does not make it harder — both give you the same result, which is a surface that never stops being tacky.
Resin runs about 1.1 g/ml and hardener about 1, so 2:1 by volume is 2.20:1 by weight. Take the by-volume number to a scale and you put in roughly 7% too much hardener — comfortably enough to leave the piece tacky forever. Brands quote it both ways, sometimes on the same label, and getting it the wrong way round is the commonest cause of a first pour that never sets.
Nothing you stir into resin takes part in the reaction. Every particle of pigment, glitter or powder is inert filler that the curing resin has to build a solid network around, so there is a load past which there is simply not enough resin between the particles. It does not fail loudly — the pour just stays faintly soft, and the usual response is to wait another week for something that is already finished. In practice that means about 6% by weight for mica powder and liquid pigment — and a great deal less than that is usually enough, because half a per cent is already a solid colour. Glow in the dark powder is the exception at 10–20%: a coarse inert crystal rather than a fine platelet, and it has to be that heavily loaded or it barely glows.
Cold resin is thick, holds its bubbles and cures slowly; warm resin is thin, releases bubbles and races. Around 21–24 °C is the usual working window. Standing the bottles in warm water for ten minutes before mixing is the standard trick for a stubborn winter pour — but warm the bottles, not the mixed batch, because heat applied after mixing shortens the working time you have left.
Dust, hair and a draught are all permanent. Resin stays open and sticky for hours, so anything that lands on it during that time is now part of the piece. Cover the pour with a box or a bin lid the moment the bubbles are out, and do not pour in the same room you just sanded in.
Your first pour, step by step
Once the two parts meet you have 20–40 minutes with a coating epoxy and a few hours with a casting one, and the clock does not stop for a missing stir stick. Level the surface with a spirit level, tape the underside of any edge you do not want resin running down, lay out the cups, the sticks, the gloves and the torch, and only then start measuring.
A kitchen scale reading to 1 g turns this from a gamble into a repeatable thing. Mix about 10% more than the calculation says: a mixing cup keeps a film on its sides you cannot get out, and you cannot go back for more mid-pour without leaving a visible join.
Unmixed resin clinging to the side of the cup is unmixed resin in the finished piece. Scrape the walls and the bottom repeatedly, turn the stick over and scrape that too, and stir slowly — whipping it in fast is how you fold air into the batch you are about to spend twenty minutes torching out.
The double-cup method is the single biggest improvement most people make. Whatever is left unmixed on the walls of the first cup stays in the first cup. It costs one extra cup and it eliminates the sticky-patch failure almost entirely.
Pass a heat gun or a small torch a few inches above the surface in a sweeping motion — the warmth thins the resin and the bubbles rise and pop. Do not hold it in one place, and do not go near a silicone mold with a naked flame. Then cover the piece, because from that moment onwards your only job is to keep dust off it.
It can be handled after about 24 hours with a coating epoxy and 48 with a casting one, and reaches full hardness at 72 hours and 7 days respectively. Touching it to check is how fingerprints become permanent. Demolding early is how a piece warps.
Resin is expensive per piece in a way that surprises people who came from candles or bath bombs — a single river table can be several hundred pounds of material before anything else. Work out the material cost per piece before you set a price, not after your first order.
Work out your own first pour
Pick a shape, enter the dimensions and the depth, and it gives you what to mix, how it splits into resin and hardener in millilitres and grams, and how many separate pours the depth needs for the resin you are using.
Open the epoxy calculator →Print the pour-depth card
Maximum pour depth and cure windows by resin type — the number that cracks a casting. Free.
Estimates, not advice. Every figure on this page is computed from published reference values and standard measures, so your own inputs, equipment and conditions will move it. Nothing here is professional advice — talk to a qualified professional before acting on it.