Epoxy words explained: a plain-English glossary for first-timers

Buying epoxy

• Epoxy kit — two bottles sold together: Part A (the resin) and Part B (the hardener). Nothing happens until you mix them; once mixed, the clock starts. Kit sizes are almost always the two bottles combined, so a “1 gallon kit” is usually half a gallon of each. Every calculator here asks for that combined size and tells you how many kits to buy.
• Mix ratio — how much of each part to use, printed on the kit. 1:1 means equal amounts; 2:1 means two parts resin to one part hardener. Some labels give the ratio by volume (measuring cups), some by weight (a scale), and they are different numbers because the two parts don’t weigh the same. Never “adjust” it — extra hardener doesn’t cure faster, it just stays soft. The mix ratio calculator converts one to the other; 1:1 epoxy by weight shows it in grams.
• Deep-pour epoxy — a slow, runny epoxy made for thick pours: river tables, castings, deep molds. Use it for anything thicker than about 1/4 in (6 mm) in one go. It releases its heat slowly, which is why it can be poured thick — and why it takes days to harden.
• Tabletop (coating) epoxy — a faster, thicker epoxy made to be poured about 1/8 in (3 mm) at a time over a surface: tables, bars, counters, paintings. Poured much thicker, it can overheat. Deep pour vs tabletop epoxy explains how to choose.
• Data sheet (TDS) — the technical data sheet: the maker’s document with the exact mix ratio, maximum pour depth, working time, recoat window and cure times. It is usually a PDF linked from the product page. When a calculator’s typical figure and your data sheet disagree, the data sheet wins.
• Waste allowance — extra resin you plan for but never see on the finished piece: the film left in the bucket and on the stir stick, small leaks, drips. Around 10–15% is common for pours; the table-top calculators here count edge drips separately and add a smaller allowance on top.

Pouring words

• Pour / lift / layer — one batch of mixed epoxy poured in one go. A thick river table is often poured in two or three lifts (layers), each allowed to firm up before the next goes on. The river table calculator works out how many lifts your depth needs.
• Max pour depth — the thickest single layer the maker says the epoxy can take without overheating, e.g. “up to 1/4 in per coat” or “2–3 in per pour”. Deeper than that, split it into lifts. Some deep-pour resins also have a minimum depth and cure slowly or stay soft if poured thinner.
• Flood coat — the clear, glassy top layer: epoxy poured over the whole surface and allowed to level itself, usually about 1/8 in thick. The 6 ft dining table example works one through.
• Seal coat — a thin first coat brushed or scraped into bare wood before the flood coat. It closes the pores so air escaping from the wood doesn’t leave bubbles in the finish. It takes very little epoxy — roughly 1–2 fl oz per square foot, more on thirsty wood.
• Self-leveling — epoxy that flattens itself out into a smooth, even coat when poured at its intended thickness. Most coating epoxies level at about 1/8 in; spread much thinner, they can ripple.
• Form (mold) — the box you pour into. For a river table it is usually melamine board with its seams sealed and lined with release tape, so the cured resin lets go. For crafts it is often a silicone mold.
• Live edge — the natural, bark-side edge of a wood slab, left wavy instead of sawn straight. River tables put two live edges facing each other, which is why the river’s width varies and has to be measured in several spots.

Time and temperature

• Working time (pot life) — how long mixed epoxy stays runny enough to pour and spread. Pot life is usually measured in the cup, and it is shorter than working time on the table, because a mass of epoxy in a bucket traps its own heat. Mix only what you can pour promptly.
• Recoat window — the period when the next coat will bond without sanding. TotalBoat, for example, gives at least 3 hours between coats of its TableTop epoxy at 70°F. Miss the window and you usually need to scuff-sand the surface first.
• Cure — the chemical hardening. “Dry to the touch” is not fully cured: a surface can feel hard in a day but take a week to reach full strength. Don’t put weight, heat or wear on it until the label’s full-cure time has passed. The cure time calculator adjusts label times for a cold or warm room.
• Exotherm — the heat epoxy gives off as it cures. In a thin coat it escapes; in a thick pour or a full bucket it builds up and speeds the reaction, which makes still more heat. Too much and the resin can crack, yellow, smoke or foam — which is why depth limits exist.

Measuring words

• fl oz vs oz — fluid ounces (fl oz) measure volume, what a measuring cup holds; ounces (oz) measure weight, what a scale reads. They are not the same for epoxy, because resin is a little heavier than water. Use whichever your label gives. How much a gallon of epoxy weighs shows the conversion.
• Mils — thousandths of an inch, used for floor coatings. 10 mils is 0.01 in (0.25 mm) — about the thickness of two or three sheets of ordinary printer paper, which is roughly 0.1 mm (4 mils) each. Floor coating data sheets give coverage at a mil thickness, often as wet film (just applied) or dry film (after it cures).
• Flakes / broadcast — colored vinyl chips thrown by hand onto a wet floor coat. “Broadcast” just means scattering them; a full broadcast covers the floor until no coating shows, a light broadcast is a sprinkle. The 2-car garage example shows how much each takes.

Where to go next

Pick the calculator for your project and the words above will turn up in its fields and results. Filling a river between two slabs: the river table calculator, with the 6 ft river table as a worked example. Coating a table or desk: the tabletop calculator. Coating a painting: the resin art calculator and the 12 × 12 canvas example. Coating a garage: the garage floor calculator. Anything else: the epoxy resin calculator. For the whole method behind the numbers, read how to calculate epoxy.