Frequently Asked Questions, Epoxy Knowledge & Training

This page collects the most common questions we get asked about epoxy: what it is, how it works, where it's used, and what you need to know before you start. Whether you're a curious hobbyist or a tradesperson exploring a new skill, you'll find straight, practical answers here. Want to take it further? Our workshops and trainings in Marbella give you the hands-on experience to put it all to use.

1. The basics: what actually is epoxy?

What exactly is epoxy?

Epoxy isn't paint, and it isn't just glue, it's a system of two liquids (resin and hardener) that, the moment you mix them, start a chemical reaction. That reaction turns the mixture into a rock-hard, glass-clear material. It's not a drying process like paint; it's a genuine transformation.

Why do you hear so many different things about epoxy?

Because "epoxy" is really an umbrella term for dozens of different formulations, each built for a different job: boat building, flooring, jewellery, worktops, industrial adhesives. What works for a river table won't automatically work for a boat hull, which is exactly why there's so much confusion floating around online.

What's the difference between epoxy, polyester and polyurethane resin?

Polyester is cheaper and faster, but more brittle and doesn't bond as well. Polyurethane is more flexible and often cures faster, but isn't as clear. Epoxy generally beats both on strength, adhesion and clarity, which is exactly why it's become so popular, from boat building to art.

What are the main types of epoxy you'll come across?

• Deep-pour (thick layers, river tables)

• Tabletop/coating resin (thin, glossy layers)

• Flooring epoxy (wear-resistant, often with fillers)

• Marine epoxy (waterproof, flexible, more UV-resistant)

• Art/casting resin (for jewellery and small objects, often UV-stable)

• Food-safe epoxy (for cutting boards, serving trays, note: only once fully cured, and not every brand is tested for it)

• Heat-resistant epoxy (for applications that need to handle high temperatures)

• Electronics potting resin (for insulating electronic components)

How do you actually mix epoxy correctly?

Two things are essential: the exact weight ratio (on a precise scale, not eyeballed) and thorough mixing, including the sides and bottom of your cup, where unmixed material likes to hide. A widely used technique is the "two-cup method": mix in cup one, then pour into a clean second cup and mix again. This stops unmixed epoxy clinging to the wall of the first cup from later causing sticky patches.

Can I speed up curing by adding extra hardener?

No, and this is one of the most stubborn myths out there. The resin-to-hardener ratio is fixed for a proper chemical reaction. Adding more hardener won't speed anything up; it'll just leave the epoxy soft, or stop it curing altogether.

What does "2K" mean on an epoxy label?

2K stands for "2-component": a system where you mix resin and hardener yourself in the correct ratio (as opposed to 1K products, which are ready-to-use and cure on their own, like some UV resins).

Why should I mix resin and hardener by weight, not by volume?

Because resin and hardener often have different densities. Equal volumes of each won't automatically give you the correct weight ratio. That's why an accurate scale is essential, get it wrong by too much and the epoxy may not cure at all.

How long can you store epoxy before using it?

Unopened, stored cool and dry (roughly 10–30°C), epoxy will often keep for years. Once opened, it's important to reseal the containers tightly straight away, the hardener in particular reacts with oxygen in the air and can become unusable. Older epoxy may also yellow slightly; that's purely cosmetic and doesn't affect curing properties.

Why does epoxy cure so slowly when it's cold?

Below roughly 15–20°C the chemical reaction slows down significantly, and a waxy film can form on the surface (sometimes called "amine blush"). That film needs to be removed, usually by cleaning and lightly sanding, before you continue working or apply another coat. Consistent temperature and humidity throughout the whole cure gives the best result.

2. Decorative epoxy: marble and stone imitation

Can epoxy really look like natural stone or marble?

Yes, and that's exactly our specialty at Epoxyworkshop.es. With the right pigments, pouring technique and layering, you get a marble or stone look that comes surprisingly close to the real thing, on floors, walls and worktops alike.

How long before a decorative epoxy floor is ready to use?

Cure times vary, but expect a few days before you can walk on it, and often a bit longer before the surface is fully chemically cured and load-bearing.

Can epoxy be used on walls and worktops too, or is it just for floors?

All three work well, it's the same technique, but the prep and pouring method differ depending on the surface and orientation (horizontal versus vertical calls for a different viscosity).

Why do you so often see tiny bubbles in other people's work, and how do you avoid them?

Bubbles form during mixing or pouring. The trick is to mix gently, stir slowly, and go over the surface with a heat gun or torch right after pouring to release any trapped air.

3. Floors, worktops & interior surfaces

What does an epoxy floor or worktop roughly cost?

The price depends heavily on surface area, thickness, the finish you want, and whether it's new build or a renovation. A simple, flat-colour floor sits at the lower end of the market; as soon as decorative work like a marble or stone look comes in, or extra scratch-resistant top coats, the price shifts toward the premium segment. Either way, think of it as an investment that pays for itself in lifespan: a well-applied epoxy floor often lasts ten to twenty years.

How long does an epoxy floor or worktop actually last?

With correct preparation and application: a very long time, often ten years or more, needing only the occasional fresh top coat if the surface loses its shine.

Is an epoxy floor scratch- or heat-resistant?

Epoxy generally holds up well against scratches and everyday household heat, but extreme heat (like a hot pan placed directly on the surface) can cause localised damage, so a trivet is still a sensible idea.

Can you apply epoxy yourself, or does it always need a professional?

Smaller DIY projects are certainly doable, but larger surfaces (floors, worktops) demand precision in prep, temperature and pour speed. Mistakes are hard to fix afterwards, which is exactly why tradespeople who've mastered it can charge properly for it.

What's a realistic price for a professional epoxy floor in Spain?

There's a wide range here. A simple, single-colour professional epoxy floor starts around €800 for 12 m² (roughly €65–70/m²) as a Spanish benchmark. As soon as design comes into play, a marble or stone look, say, or extra protective layers like a scratch-resistant top coat, the price climbs fast: think closer to €150/m². That price gap comes down to craftsmanship: anyone can lay down a flat-colour floor, but pulling off a convincing marble look is a specialism, and that specialism is exactly what this workshop is about.

Can an epoxy floor or worktop really handle any amount of heat?

Not unlimited amounts. Epoxy has what's called a glass transition temperature (Tg): above that point, the material can temporarily soften. For normal household use this is rarely an issue, but for structurally high temperatures (a floor that sits in direct sun a lot, or heavy industrial use) it's worth factoring in when choosing your product.

Can an epoxy floor go over underfloor heating?

Yes, but not while it's being applied and curing, keep the underfloor heating off or on a low setting then, otherwise the extra heat speeds up curing too much and cuts your working time short.

Why do you sometimes see joints in an epoxy floor?

On larger surfaces, expansion joints are often built in to prevent cracking, the material needs a little room to "move" with temperature swings. These joints are usually left open or finished with a flexible sealant rather than epoxy itself.

4. Wood & furniture (tables, river tables, bar tops)

What's a river table, and how is it made?

A river table combines a wooden slab with a "river" of cast resin, usually clear or coloured, that fills the gap between two pieces of wood. The result looks like a flowing river running through the timber.

How thick can you pour an epoxy layer without problems?

That depends on the product: standard tabletop epoxy is usually limited to a few centimetres per layer, while specialist deep-pour epoxy can be poured much thicker in one go without overheating.

Why do you sometimes need to pour epoxy on a wooden table in layers?

To prevent overheating: too thick a pour at once can generate so much heat while curing that it bubbles, cracks, or yellows. Pouring layer by layer keeps the process under control.

Can epoxy-coated furniture stay outdoors?

With a good UV-resistant top coat, yes, but plain epoxy on its own will yellow in the sun over time. Just like with boats: protect the outer surface with an extra layer.

5. Jewellery & small work (casting resin, art)

Is cured epoxy safe to wear as jewellery?

Yes, once fully cured, epoxy is inert and safe for skin contact. The risk lies in the wet, uncured stage; that's where you do need to be careful.

Can I use epoxy for a chopping board or anything that touches food?

Fully cured epoxy is generally considered food-safe, but always check the specification of the product you're using, not every brand is tested or suitable for that.

Why does my jewellery piece stay tacky after curing?

Usually down to an incorrect resin-to-hardener ratio, or mixing too quickly or carelessly. A thin fresh coat on top can sometimes rescue it, but the underlying cause is almost always in the mixing process.

How thick can I pour for jewellery, tables, or large encapsulations?

This varies a lot by application: for jewellery, trays and small objects you're usually working with layers up to 5 mm–1 cm (for a quick, clear cure); for tables that can go up to 1–10 cm depending on the number of layers; for large encapsulations of whole objects, sometimes up to 10–16 cm with specialist deep-pour systems. Always check the specific product's data sheet, pouring more than the system is rated for is one of the most common mistakes.

Can I embed fresh flowers or insects in epoxy?

Yes, but they need to be properly dried and sealed first. Moisture trapped inside can cause discoloration or oxidation within the resin months later.

Can I save leftover mixed epoxy for later?

Not really once it's mixed, the chemical reaction has already started. You can sometimes store unopened, unmixed components in the freezer to extend shelf life; just make sure to let them come back up to room temperature before use.

6. Safety & health

Is epoxy toxic or dangerous to work with?

In its wet form, epoxy contains substances that can cause irritation and, with repeated contact, allergic reactions. Once fully cured, it's inert and safe. So the real focus should be on the working process itself.

Can you develop an allergy to epoxy?

Yes, it's called sensitization: the more often your skin comes into contact with uncured epoxy, the higher the chance your body eventually starts reacting to it. That's why gloves and a clean way of working aren't overkill, even for seasoned professionals.

What protective gear do you need when working with epoxy?

Think nitrile or vinyl gloves (ordinary rubber lets epoxy through within seconds), good ventilation, and for longer or larger-scale work, a suitable respirator mask.

Is it worth wearing a mask even when it's not strictly required?

Several specialist suppliers say the same thing: there's usually no legal requirement, but if you're asking yourself whether you need a mask, you're probably someone who prefers to play it safe anyway, so the answer is simply: yes, wear it.

Can you work with epoxy during pregnancy or breastfeeding?

Caution is warranted here. Several specialist sources recommend avoiding contact with uncured epoxy (and similar resins) during pregnancy and breastfeeding, and keeping the material out of reach of children too. If in doubt, or if symptoms persist after exposure, it's sensible to consult a doctor.

Does epoxy smell strong, and is that harmful?

Some products barely smell, others more so, it depends on the formulation. A well-ventilated space is a good idea regardless of how strong the odour is.

What do the hazard symbols on an epoxy container mean?

Within the EU, labels on uncured epoxy often carry these GHS symbols: irritant/sensitizer (can cause temporary irritation on contact or inhalation), corrosive (can cause skin burns), and hazardous to aquatic life (in uncured form). Note: these symbols apply to the liquids in the container, once properly cured, the end result is inert. When in doubt, always check the product's safety data sheet (SDS); not every brand is the same.

Is every epoxy on the market equally safe?

No. Some epoxy systems carry heavier hazard labels (long-term health hazard, or even toxic) because they're suspected of carcinogenic or mutagenic properties. Responsible suppliers deliberately exclude that kind of product from their range, a good question to ask whoever you're buying materials from.

What protective equipment do you need exactly, and when?

A handy rule of thumb:

Session type

Minimum PPE

Short session, well-ventilated space

Nitrile gloves + safety glasses

Longer session or less ventilation

Half-face respirator (correct vapour filters) + gloves + safety glasses + skin-covering clothing

Spraying epoxy

Full-face respirator + gloves + full-coverage clothing

7. For tradespeople: what's in it for your business?

I'm a painter/plasterer/kitchen installer, why would I bother learning epoxy?

Because right now, you're probably referring clients elsewhere the moment they ask for a marble worktop or a decorative floor. That revenue goes to someone else. With the right skill, that job, and the money that comes with it, stays with you.

How much extra can an epoxy skill add to my business?

That varies by market and region, of course, but decorative epoxy finishes generally sit in the premium segment, you're not selling a standard job, you're selling a specialism with far less competition.

Do you need a diploma or certificate to work professionally with epoxy?

There's no legally required diploma, but clients, especially at the higher end, value demonstrable training and experience. That's exactly what our workshop in Marbella is built around: hands-on experience you can put to use, and show off, straight away.

Can I take a private lesson on just one specific topic, instead of the full workshop?

Yes, that's negotiable, get in touch via epoxyworkshop.es so we can see what fits what you already know and what you still want to learn.

8. The workshop itself: practical questions

How long is the workshop at Epoxyworkshop.es?

There are two packages: a 2-day Professional Training and a 3-day Intensive Pro Training (which also covers Ocean Art and Geode Art). Check epoxyworkshop.es for current content and pricing.

What language is the workshop taught in?

The workshop is taught in English. We also speak Dutch, French and German (and pick up a bit of Spanish every day), so don't hesitate if English isn't your first language.

Can the workshop take place at my own location?

With enough participants, that's possible, for a mileage fee. Get in touch to discuss the options.

Is the workshop suitable if I'm not a tradesperson, just interested?

Absolutely, alongside the professional trainings, there's also the low-threshold Epoxy Art Experience for anyone who wants to get a taste of the technique.

9. Troubleshooting

My epoxy is getting hot and starting to smoke, what's happening?

That's called a "flash cure": the chemical reaction between resin and hardener generates heat, and if you've mixed too large a batch, that heat can't escape fast enough. The result is a mixture that keeps getting hotter and can even melt the mixing cup. Fix it immediately by moving the cup outside or pouring water over it. Prevent it by never mixing more than you can use within the working time, and on warm days, working in a wide, shallow container so heat can escape more easily.

My epoxy stays tacky, even after days, how do I fix it?

The most common cause is an incorrect resin-to-hardener ratio, or insufficient mixing (the sides and bottom of the cup are easily missed). A thin fresh coat on top can sometimes still save it.

I see tiny pinholes after sanding, how do I prevent that?

Pinholes usually come from trapped air bubbles that only become visible after sanding. Careful mixing, stirring slowly, and de-gassing with a heat gun or torch right after pouring all help prevent this.

Why doesn't my epoxy stick properly to the substrate?

Usually down to inadequate prep: grease, dust or moisture on the surface disrupts adhesion. Thorough cleaning, and light sanding where needed, is the foundation of a successful result.

10. Gluing, laminating & special applications

Can epoxy be used as glue?

Absolutely, epoxy makes an excellent adhesive that bonds to a huge range of materials and is very strong. Because plain mixed epoxy is often too thin to fill a glue joint, it's usually thickened with a filler, cotton fiber for woodworking, for example, or another thickening agent for other materials.

What exactly is laminating with epoxy?

Laminating means applying epoxy to fiberglass, aramid or carbon fabric, so the resin soaks through ("impregnates") the weave and, together, they form a strong, hard laminate. This is used to coat objects or, if thick enough, as a standalone structural material, think boat or surfboard building.

How do I know if I've used enough epoxy when laminating?

White, dull patches in the weave mean too little resin; shiny, wet patches mean too much. A laminating squeegee helps you spread the epoxy so the weave pattern stays just visible, that's the sign of the right amount.

Can epoxy repair rotten window frames or timber?

Yes, this is one of its classic uses. Liquid epoxy soaks deep into weakened wood and hardens it from the inside out, after which you can sand and finish it as if nothing had happened. For larger holes, this is often combined with an epoxy filler.

Is epoxy suitable for waterproofing a shower, hot tub, or caravan floor?

Yes to all three, provided you use the right type and prepare the surface properly. For vertical surfaces (shower walls) you need a thicker, non-sag epoxy; for a floor or caravan base, a system that settles well into gaps and cracks.

Can epoxy be used to bond plastic or PE/PP?

That's tricky, polyethylene and polypropylene are notorious for the fact that almost nothing sticks to them, epoxy included. Special pre-treatments or other adhesive types exist for this; it's one of the few materials where "plain" epoxy isn't the answer.

11. Boats & waterproofing (marine epoxy)

Can epoxy really make a boat waterproof?

Yes, epoxy soaks into the wood, hardens the fibers and forms a sealed layer that keeps water out. It's exactly why epoxy has such a solid reputation in boat building: from stitch-and-glue kayaks to classic wooden yachts.

Do I need "marine epoxy" specifically, or will regular epoxy do?

Marine epoxy is specifically formulated to withstand salt water, temperature swings and UV, and is often somewhat more flexible so it can move with the hull. Regular epoxy can work fine in dry, sheltered applications, but for a hull that sits in the water, marine-grade is genuinely the safer choice.

How many coats of epoxy does a hull need?

Usually 2 to 3 coats are recommended, with enough cure time between each. Applying too thin is the most common mistake, it leaves the protection porous.

Can epoxy repair wood rot?

Definitely, it's one of epoxy's real strengths: it penetrates weakened wood, hardens it from within, and can then be sanded and finished as if nothing had happened.

Why does epoxy on a boat yellow over time?

UV light slowly breaks down the molecules in epoxy, causing a yellow tint. That's why an outdoor application almost always calls for a UV-resistant top coat (varnish or coating) over the epoxy itself.

Have a question that's not covered here? Come and ask it in person, that's what the workshop is for. Visit epoxyworkshop.es for dates, pricing and availability.