Epoxy vs resin: what's the difference?
Here's the short version: all epoxy is resin, but not all resin is epoxy. "Resin" is the broad family; epoxy is one member of it — like asking the difference between an apple and fruit.
Resin is the category, not a product
"Resin" is an umbrella term for liquids that cure into a solid plastic. Several different chemistries fall under it, and they behave very differently. The four you'll meet most often are epoxy, polyurethane (PU), UV, and polyester. When someone says "I work with resin," they could mean any of these — which is exactly where the confusion starts.
So comparing "epoxy vs resin" isn't really comparing two options. It's comparing one specific type against the whole group it belongs to. The useful question is which resin — and that's what the rest of this guide answers.
The labeling trap: in a two-part epoxy kit, the bottle marked "resin" is just Part A — the component you mix with the "hardener" (Part B). So "resin" can mean the whole category, or one specific chemistry, or one half of a kit. Context tells you which.
Epoxy resin
Epoxy is the all-rounder and the most popular for casting and coating. It's a two-part system: you mix a resin with a hardener and a chemical reaction cures it solid. Epoxy is prized for high clarity, strong adhesion, and low shrinkage, which is why it dominates table tops, deep pours, river tables, and floor coatings.
- Best for: tables, river tables, floors, clear castings, coatings
- Cure: typically 24–72 hours, by chemical reaction
- Strengths: clarity, bond strength, low shrink, thick single pours
UV resin
UV resin cures in minutes — but only under a UV lamp, and only in thin layers light can reach. That makes it fast and convenient for small work, and impractical for anything thick or opaque.
- Best for: jewelry, small coatings, fast studio production
- Cure: minutes, under a UV light
- Limit: thin layers only — light can't reach deep
Polyurethane (PU) resin
Polyurethane casting resin is fast and tough. It demolds quickly and captures fine detail, which makes it the go-to for molds, prototypes, and high-volume reproduction — but it's typically less clear than epoxy and more sensitive to moisture.
- Best for: molds, prototypes, figurines, reproduction
- Cure: fast — often demolds in 15–30 minutes
- Trade-off: tough and fast, but less optically clear
Polyester resin
Polyester resin is the low-cost workhorse of fiberglass and boat repair. It's strong and cheap, but it shrinks more, smells strongly, and yellows over time — so it's rarely the right choice for clear decorative work.
- Best for: fiberglass, boat & auto repair, industrial laminating
- Trade-off: cheap and strong, but smelly and prone to yellowing
Quick comparison
| Type | Best for | Cure | Clarity |
|---|---|---|---|
| Epoxy | tables, pours, floors | 24–72 hr | excellent |
| UV | jewelry, small work | minutes (lamp) | good (thin) |
| Polyurethane | molds, prototypes | 15–30 min | fair |
| Polyester | fiberglass, repair | fast | fair, yellows |
So which should you use?
Match the resin to the job, not the other way round. For a clear table top or a river table, use a deep-pour epoxy. For jewelry or fast small pieces, UV resin. For molds and reproduction, polyurethane. For fiberglass and structural repair, polyester. Most decorative and functional work that people call "resin art" or "resin furniture" is, in practice, epoxy.
Working out quantities? Once you've picked epoxy, our epoxy calculator tells you exactly how many gallons a table top, deep pour, or river table needs.
Frequently asked questions
Is epoxy the same as resin?
Not exactly. Resin is the broad category of liquids that cure into solid plastic. Epoxy is one type of resin — so all epoxy is resin, but resin also includes UV, polyurethane, and polyester.
Why is the bottle in my epoxy kit labeled "resin"?
Two-part epoxy comes as a resin (Part A) and a hardener (Part B). On the kit, "resin" refers to just Part A — the part you mix with hardener to start the cure.
Which resin is best for a river table?
A deep-pour epoxy. Epoxy gives the clarity and low-shrink cure thick pours need; UV and polyurethane aren't suited to deep, clear castings.