Safe Resin Art

Epoxy resin is a plastic made from two liquid parts, the resin (Part A) and the hardener (Part B), which react chemically and harden once they’re mixed. In that reaction, the resin’s epoxy groups bond with the hardener’s amines to form a three-dimensional network. The result is a solid plastic called a thermoset. The process can’t be reversed: cured epoxy resin can’t be melted or dissolved again.

Source: Safe Resin Art, chapter 2, pages 24 to 25.

Strictly speaking, epoxy resin doesn’t dry; it cures through a chemical reaction. That reaction releases heat, and depending on the system, it can give off fumes, so you need protection even when your piece only seems to be “drying.” How long it takes depends on the resin: roughly 12 to 24 hours for top coat resin, 24 to 48 hours for standard casting resin, 48 to 72 hours for deep pour resin, and 5 to 7 days for ultra deep pour resin. Your technical data sheet (TDS) gives the exact times, and a piece often reaches full strength only after about a week.

Source: Safe Resin Art, chapter 2, pages 30, 33, and 43; chapter 9, page 115.

“Resin” is a catch-all term, and epoxy resin is just one group within it. PU (polyurethane) resin suits heavily used surfaces such as floors and furniture and requires a respirator suitable for isocyanates. UV resin cures under UV light and works only for thin layers and small projects such as jewelry. It’s usually an acrylate, and many acrylates can sensitize the skin. You need protective equipment with all three types of resin.

Source: Safe Resin Art, chapter 2, page 39.

In liquid form and while you work with it, epoxy resin can harm your health; correctly mixed and fully cured, it’s considered chemically stable. In liquid form, many components of the resin and hardener can sensitize the skin and be absorbed through it, and some hardeners are also corrosive; your product’s safety data sheet (SDS) tells you what it contains. While you work and while it cures, volatile components can get into the air, depending on the system, and they can irritate and sensitize your eyes, nose, and airways. A full cure takes days to weeks, so keep a freshly poured piece out of living rooms and bedrooms for at least a week, and remember that hardness or a lack of smell alone doesn’t prove a full cure.

Source: Safe Resin Art, chapter 2, page 41; chapter 3, page 50; chapter 4, page 58; chapter 7, page 97; chapter 10, page 126.

According to the European Chemicals Agency (ECHA), the usual building blocks of epoxy resin are not classified as carcinogenic, but they are classified as skin sensitizers. Whether your product contains substances that are carcinogenic, mutagenic, or toxic to reproduction, known as CMR substances, is stated in the safety data sheet. Be careful with additives: some azo dyes in powder pigments can break down in the body into aromatic amines, some of which can cause cancer. Casting powders containing quartz can contain respirable crystalline silica, which can cause silicosis and lung cancer. For these, I recommend dust extraction and a well-fitting FFP3 mask or, in the US, a P100 respirator.

Source: Safe Resin Art, chapter 8, pages 107 to 108; chapter 9, page 113; glossary, page 219.

By complete documentation: if a product doesn’t come with a complete safety data sheet (SDS), don’t use it. The SDS lists the hazards, first aid, protective equipment, and disposal, and reputable manufacturers provide it without hesitation. Look for REACH-compliant, clearly declared raw materials (in the US, the closest counterpart to REACH is the Toxic Substances Control Act, TSCA), and ask for written confirmation that the hardener is free of nonylphenol, which some 1:1 hardeners contain. Price alone says little about safety, so check the technical and safety data sheets instead.

Source: Safe Resin Art, chapter 9, pages 112 to 114.

The respiratory protection you need depends on your epoxy resin, the additives, and the safety data sheet. For Resin Art, I recommend a half-face or full-face respirator with suitable replaceable filters, for example A2P3, a combination filter for organic vapors and particles: A2 holds back many organic vapors with a boiling point above 149°F (65°C), and P3 filters 99.95% of particles. But A2P3 doesn’t suit every resin, hardener, spray, or solvent; what counts is the safety data sheet and the instructions from the respirator and filter manufacturer. In the US, choose a NIOSH-approved respirator and cartridge combination, often organic vapor (OV) cartridges with P100 filters; OV/P100 and A2P3 are different systems, not interchangeable approvals. A full-face respirator also protects your eyes from irritating vapors.

Source: Safe Resin Art, chapter 4, pages 63 to 64.

No. FFP masks, like N95 masks, filter only particles, not vapors. The chemical vapors from epoxy resin pass right through them, as if through an open window. FFP3 is the highest class of particle masks and filters at least 99% of particles, but when you pour, it gives you a false sense of security. For sanding and handling powders, though, a well-fitting FFP3 mask is useful particle protection; in the US, P100 filters come closest to P3, and an N95 roughly matches FFP2.

Source: Safe Resin Art, chapter 4, page 63; chapter 8, page 107.

With a user seal check, every time you put on your respirator. One common example: cover the filter openings with your hands and inhale gently; the mask should pull slightly toward your face and stay there while you hold your breath. If it doesn’t, reposition the mask, tighten the straps, and repeat the check. Hair, makeup, greasy creams, and beards or stubble along the seal line break the seal, and your manufacturer’s instructions always come first.

Source: Safe Resin Art, chapter 4, page 65.

On a fixed change schedule, not when you notice a smell. How long a gas filter lasts depends on the vapor concentration, temperature, humidity, and your breathing; the filter manufacturer’s guidance is what counts. If you smell vapors even though your mask fits properly, leave the work area right away and change the filter only in clean air. Write the opening date on the filter with a waterproof marker.

Source: Safe Resin Art, chapter 4, pages 66 and 68.

No. Even low-odor epoxy resin can release substances while it cures that cause irritation or harm your health. Your sense of smell isn’t a reliable warning system: many substances are hard to smell or have no odor at all, even in products labeled “low-odor” or “low-VOC.” On top of that, your nose quickly gets used to an odor, even though the concentration in the air stays the same. So always work with good ventilation, a respirator, and according to the safety data sheets.

Source: Safe Resin Art, chapter 4, pages 59 to 60.

No. Even short tasks add to your total exposure. Picture your body as a barrel: every unprotected minute lets a little more drip in, until one day a single drop is enough to make it overflow. What matters isn’t only the amount per day, but the total over weeks, months, and years. And sensitization doesn’t follow a predictable countdown.

Source: Safe Resin Art, chapter 4, page 61.

Stop working right away and get to fresh air. If you feel unwell, get medical advice right away, bring the safety data sheet, and keep the emergency numbers handy, including poison control (in the US, Poison Help at 1-800-222-1222; in the UK, NHS 111). Fumes from epoxy resin can irritate your nose, throat, and eyes and cause coughing, hoarseness, or a scratchy throat. If you smell fumes even with your respirator on, leave the work area and check the filter and the seal only in clean air.

Source: Safe Resin Art, chapter 4, pages 58 and 68; checklist no. 4, page 192.

Use chemical-protective gloves made of nitrile or butyl rubber, tested to EN ISO 374 (or the equivalent in your country), and check them against your product’s safety data sheet. Thin disposable gloves are splash protection only: once one gets resin on it, change it right away. According to GESTIS, latex is not suitable for typical hardeners, thin disposable vinyl gloves protect only briefly, and leather or fabric gloves don’t protect at all. A long cuff is ideal. Double gloving has proven itself: two pairs of nitrile gloves, the outer pair one size larger.

Source: Safe Resin Art, chapter 5, page 74.

Stop working right away and dab the resin off with a clean, dry paper towel without rubbing. Take off contaminated clothing while wearing protective gloves, and rinse the area under running lukewarm, not hot, water for at least 5 minutes, and for at least 15 minutes if hardener is involved or the skin burns. Then wash with mild soap; section 4 of the safety data sheet is what counts. Never use acetone, alcohol, or solvents, since they can carry the resin deeper into your skin. If redness, itching, blisters, or swelling show up afterward, see a doctor.

Source: Safe Resin Art, chapter 5, page 75.

See a doctor, ideally a dermatologist experienced with contact allergies, and bring the safety data sheets for the resin and the hardener. Redness, swelling, itching, or blisters after contact can mean your skin is reacting to epoxy resin; the safety data sheets help your doctor understand the chemical makeup. Don’t wait: according to the German Social Accident Insurance (DGUV), once you’re sensitized to epoxy resin, it lasts for life. The rash heals if you avoid contact, but it comes back quickly with the next exposure. Get a medical assessment before you keep working with epoxy resin.

Source: Safe Resin Art, chapter 3, page 50; chapter 5, pages 72 and 75.

Yes. Many components of the resin and hardener can sensitize the skin, and according to the German Social Accident Insurance (DGUV), this sensitization lasts for life. Here’s how it develops: reactive components penetrate the outer layer of your skin, and your immune system learns to recognize them as foreign, often without you noticing, with no burning or itching. The next time you have contact, your skin can react with redness, swelling, itching, or blisters. Repeated contact increases the risk, but there’s no predictable countdown, and not everyone becomes sensitized. According to the DGUV, epoxy resins are among the most common causes of occupational allergic skin disease.

Source: Safe Resin Art, chapter 1, page 19; chapter 3, page 50; chapter 5, page 72.

For mixing, pouring, and any splash risk, you need chemical splash goggles with an all-round seal or a full-face respirator. That means goggles rated EN 166 “3” or EN ISO 16321, or in the US, ANSI Z87.1 “D3.” Regular prescription glasses, sunglasses, and reading glasses don’t protect you, and safety glasses with side shields are basic protection only, not splash-tight. If you wear glasses, use a spectacle kit for your full-face respirator or goggles that fit over your glasses.

Source: Safe Resin Art, chapter 6, page 80.

Rinse right away with clean, lukewarm running water, without stopping, for at least 15 minutes. Hold the eye wide open, with help if needed, and direct the water from the inner corner of the eye outward; remove contact lenses only if it’s easy, and keep rinsing. Don’t use eye drops, ointments, or home remedies, and afterward go straight to an eye doctor or the emergency room, with the safety data sheet or at least the product name and manufacturer. Post the numbers for your eye doctor, poison control, and the nearest emergency room where you can see them at your workspace before you start.

Source: Safe Resin Art, chapter 6, pages 82 to 84.

No. Epoxy resin doesn’t belong in children’s hands, not for crafts and not for experiments, and my recommendation is clear: no epoxy resin for anyone under 18. While you work with it, volatile components can get into the air, and reactive ingredients can also be absorbed through the skin and lead to sensitization. In Germany, the law, the Youth Employment Protection Act (Jugendarbeitsschutzgesetz, section 22), covers only the workplace: young people may not be employed in work that exposes them to the harmful effects of hazardous substances, with narrow exceptions for vocational training. In Great Britain, employers must assess and control the risks to young workers; in the US, check federal and state child labor laws. For home, there are creative alternatives such as air-dry clay, polymer clay, or nontoxic water-based acrylic paints.

Source: Safe Resin Art, chapter 3, pages 46 and 53.

It can be a risk for you and your baby, so my recommendation is: no epoxy resin while you’re pregnant or breastfeeding. Epoxy resins contain reactive substances that can get into the air while you work and be absorbed through the skin, and some ingredients may be classified as toxic to reproduction (see the safety data sheet). In German workplaces, sections 11 and 12 of the Maternity Protection Act (Mutterschutzgesetz) prohibit work with certain hazardous substances, such as those toxic to reproduction or carcinogenic; US and UK rules differ, so check your local regulations. The law doesn’t apply to you at home, but my recommendation stays the same: give yourself this break and talk to your doctor or midwife.

Source: Safe Resin Art, chapter 3, page 48.

Get individual medical advice first. This applies if you have existing or multiple allergies, chronic skin conditions such as eczema, atopic dermatitis, or psoriasis, chronic airway diseases such as asthma or COPD, or immune system conditions. Many components of the resin and hardener can sensitize the skin; which ones your product contains is stated in the safety data sheet. An assessment from a specialist, such as an allergist or an occupational medicine doctor, is recommended; bring the safety data sheets for the products you plan to use.

Source: Safe Resin Art, chapter 3, page 50.

A living space isn’t suitable as a permanent workspace; ideally, you work in a room that’s separate from where you live. The kitchen, living room and bedroom, damp rooms such as bathrooms or laundry rooms, and children’s rooms are off-limits. A separate, lockable room that you use only for epoxy resin and that is clearly off-limits to children and pets works well. If you use a living space at all, do so only temporarily, with full protective equipment, active ventilation, and for small jobs such as sealing or mixing colors.

Source: Safe Resin Art, chapter 7, pages 88, 90, and 94.

Actively, not passively: a window cracked open usually isn’t enough. Air should flow from your workspace toward the outside, never across the resin toward you. Most effective is extraction near the source that captures vapors before they reach your breathing zone and vents them outdoors. Cross-ventilation, a fan, or airing out every 30 to 60 minutes can help, but they don’t replace the ventilation your products and tasks require.

Source: Safe Resin Art, chapter 7, pages 94 to 95.

Ideally a room temperature of 64°F to 72°F (18°C to 22°C) and 40% to 60% humidity. Resin and hardener should be the same temperature as the room, so let them acclimate for at least 12 hours, ideally 24. Below 64°F (18°C), the resin gets thicker and cures more slowly; above 82°F (28°C), the reaction runs too fast, and more vapors are released. Above 60% humidity, amine blush can form, a waxy film; if your technical data sheet gives other values, follow the data sheet.

Source: Safe Resin Art, chapter 7, page 92.

Liquid resin and hardener can harm pets, too, for example if they leave paw prints in a fresh pour or lick contaminated surfaces. That’s why your workspace should be lockable or clearly off-limits, especially to children and animals. Don’t let pets into the curing area either while the resin is still giving off vapors. Store resin, hardener, and waste in a lockable cabinet so animals can’t knock anything over.

Source: Safe Resin Art, chapter 7, pages 87, 90, and 102; chapter 10, pages 120 and 127.

Work it out from the volume of your mold and the density of the resin. For geometric shapes such as rectangles, circles, or spheres, a free online epoxy resin calculator helps. For silicone molds, fill the mold with water, measure the amount in milliliters, and calculate: resin needed in grams equals water volume in milliliters times density in g/cm³. For example, a mold that holds 3.4 US fl oz (100 ml) of water at a density of 1.10 g/cm³ needs about 3.9 oz (110 g) of mixed resin and hardener. You’ll find the exact density in the technical data sheet, and if you note the volumes of your molds, you’ll plan more precisely next time and mix only what you really need.

Source: Safe Resin Art, chapter 2, page 35; chapter 10, page 124.

The way your technical data sheet says: if it gives a weight ratio, weigh; only if it gives a volume ratio, often 1:1, measure by volume. Resin and hardener have different densities. If you measure a weight ratio by volume, the ratio is off at the molecular level, and many molecules never find a reaction partner. For small projects, you need a scale that reads to about 0.0035 oz (0.1 g); for larger pours, about 0.035 oz (1 g) is fine.

Source: Safe Resin Art, chapter 2, pages 26 to 27.

Use the 3-3 mixing method: stir for three minutes, transfer to a clean cup, and stir for another three minutes. Stir evenly in a spiral and keep scraping the bottom and sides, because unmixed material clings there. Mixing too briefly leads to sticky spots, milky cloudiness, or soft areas. The working time starts the moment resin and hardener meet.

Source: Safe Resin Art, chapter 2, pages 28 to 29.

Pot life is the length of time a freshly mixed batch of epoxy resin stays workable in the mixing cup. It ends when the mix thickens considerably, usually when the original viscosity has doubled, and it’s a technical value measured in the lab, for example with a 3.5 oz (100 g) batch at a constant room temperature. Working time, when you can still shape the resin even after pouring, is usually longer in practice, because the resin reacts more slowly in a thin layer. Start a timer when you mix, and mix only as much as you can use within 15 to 20 minutes.

Source: Safe Resin Art, chapter 2, page 35; checklists no. 1 and 2, pages 189 to 190; glossary, page 218.

As thick as your resin’s technical data sheet allows as its maximum pour depth. As a rough guide: top coat resin 1/32 to 3/16 in (1 to 5 mm), standard casting resin 3/16 to 3/4 in (0.5 to 2 cm), deep pour resin 3/4 to 2 in (2 to 5 cm), and ultra deep pour resin up to about 4 in (10 cm). If you pour a resin made for thin layers much thicker, it can overheat dangerously, because the thicker the layer, the more heat builds up. Several thinner layers release the heat in a more controlled way and cause fewer bubbles, discoloration, and cracks.

Source: Safe Resin Art, chapter 2, pages 32 to 34; chapter 7, page 99.

Because curing is an exothermic reaction: it releases heat, and heat speeds the reaction up even more. The more resin you mix or pour at once, the hotter it gets inside; with large amounts, 212°F (100°C) and higher isn’t unusual, and even at a depth of 2 in (5 cm) in a cup, it can climb above 176°F (80°C) within minutes, depending on the system. Choose a resin that matches your pour depth, and work with small batches and shallow containers. Mix only as much as you can use within 15 to 20 minutes.

Source: Safe Resin Art, chapter 2, pages 30 to 35.

Don’t pick up the cup, and keep everyone away. Warning signs are a cup that suddenly gets very hot, bubbling like boiling water, visible fumes, and a sharp smell. If there’s fire, heavy smoke, or any doubt about your safety, leave the room and call the fire department; don’t stay inside to ventilate. Never put hot or still-reacting resin in the trash; let it cool down completely first.

Source: Safe Resin Art, chapter 2, page 30; chapter 7, page 99.

Usually it’s the wrong mix ratio, mixing too briefly, or a temperature that’s too low. If there’s too much resin, epoxy groups are left without a reaction partner, the surface stays sticky, and time won’t fix it. Poorly mixed areas lead to sticky spots or soft zones, and below 64°F (18°C) resin cures more slowly; some systems no longer react properly below 59°F (15°C). Resin that’s too old can also cure incompletely. Touch sticky resin only with gloves, because uncured resin can still irritate or sensitize your skin.

Source: Safe Resin Art, chapter 2, pages 26 to 29; chapter 7, page 92; chapter 10, page 121.

Let the mix rest for a moment after stirring, and many fine bubbles will rise to the surface on their own. Make sure resin and hardener are at room temperature, because cold components are thick, and air escapes less easily. Pour several thinner layers rather than one thick one; that reduces bubbles noticeably. You can pop surface bubbles right after pouring with a torch or a heat gun, but never near dried flowers, alcohol, sprays, or other flammable materials.

Source: Safe Resin Art, chapter 2, pages 29 and 34; chapter 7, pages 93 and 98.

Warm the closed container in a water bath, because usually the resin has just crystallized, which is a physical change, not a product defect. Like honey in a cold pantry, molecules line up into solid structures, almost always in the resin (Part A), helped along by cold and temperature swings. Set the container about halfway into water at 122°F to 140°F (50°C to 60°C), never submerge it, turn it regularly until everything is clear, and let the resin cool to room temperature before mixing. If the crystals don’t dissolve, don’t use the resin, and ask the manufacturer.

Source: Safe Resin Art, chapter 10, pages 121 to 123.

Sand only once the resin has fully cured; at room temperature, many epoxy resins reach full strength after about a week, some only after several weeks. Your resin’s technical data sheet gives the exact time, and depending on the resin, the final Shore hardness may be reached only after 7 to 30 days. In the first firm stage, you can touch the piece, but sanding and polishing still have to wait. Sanding dust from resin that hasn’t fully cured can still be chemically reactive.

Source: Safe Resin Art, chapter 2, page 41; chapter 8, page 107; chapter 9, page 115.

Yes. Epoxy sanding dust is so fine that it can travel deep into your airways. The German Social Accident Insurance (DGUV) recommends at least P2 or FFP2; I recommend P3 (in the US, P100), plus safety glasses. The dust can still be reactive if the resin wasn’t fully cured, and it often contains pigment residue and additives. Sand with extraction, ideally a dust extractor of dust class M or H (in the US, look for HEPA filtration). Wear nitrile gloves even when you wet-sand, and never pour sanding slurry or resin leftovers down the sink.

Source: Safe Resin Art, chapter 7, page 103; chapter 8, page 107.

As dust, yes: pigment and glitter particles can be inhaled and irritate your airways. Mineral pigments can contain impurities, depending on where they come from. So buy only from suppliers who tell you what’s in their products and provide a safety data sheet. Never weigh or stir in powders without respiratory protection and gloves, not even small amounts.

Source: Safe Resin Art, chapter 8, pages 107 to 108.

The smell is often gone after one or two hours, but the substances stay active much longer. A freshly poured piece gives off vapors even when it already feels solid, so keep it out of living rooms and bedrooms for at least a week. Let it cure somewhere ventilated, because at room temperature many epoxy resins reach full strength only after about a week and can still smell slightly until then. Whether it smells is no measure of safety.

Source: Safe Resin Art, chapter 2, page 41; chapter 4, pages 59 to 60; chapter 7, pages 88 and 102; chapter 9, page 115.

Not across the board. In the EU, strict rules apply to anything that comes into contact with food: it must not release substances in amounts that could harm health. Since 2025, new EU rules on bisphenols have also applied, and they affect many epoxy resins. A “food safe” claim covers only the conditions tested, for example brief contact with cold, dry food; in the US, the FDA doesn’t approve individual craft resins, and “FDA compliant” is the maker’s own claim. For a cutting board, serving board, or tray, the piece must be fully cured, the food-contact layer must not contain pigments or glitter, and if you want to sell it, you need documentation that covers the finished piece, not just the resin. A dining table made of correctly mixed, fully cured epoxy resin is considered chemically stable, but it doesn’t belong in living spaces during the first week after pouring. My recommendation: no hot, fatty, or acidic foods, and no dishwasher.

Source: Safe Resin Art, chapter 2, page 41; chapter 9, page 116; chapter 10, page 126.

No. Resin Art doesn’t belong in the dishwasher. Cured epoxy resin is a thermoset, and many art resins start to soften at surprisingly low temperatures. Heat, moisture, and harsh detergent can turn the surface dull or rough, and the piece can warp. Clean epoxy resin pieces by hand with mild soap and a soft cloth.

Source: Safe Resin Art, chapter 9, pages 115 to 117.

Yes. UV light can make epoxy resin yellow over time, even high-quality, UV-stabilized resin. That’s a natural chemical process, because even the best UV stabilizers have their limits. So keep pieces out of prolonged direct sunlight, ideally on the shady side of the room, and don’t use them permanently outdoors unless they were made for it. Outdoors, epoxy resin needs a UV-resistant sealer.

Source: Safe Resin Art, chapter 2, page 39; chapter 9, pages 115 and 117.

Yes. Clear, curved pieces such as spheres or domes can focus sunlight like a magnifying glass. The focused light can get hot enough to ignite paper or fabric or to scorch wood. So don’t put these pieces on a windowsill or in direct sunlight. And never leave them in a parked car.

Source: Safe Resin Art, chapter 9, page 115.

Dry, frost-free, out of direct sunlight, and ideally at a steady 64°F to 72°F (18°C to 22°C), unless your technical data sheet says otherwise. Close every container right after use, because hardener reacts with moisture in the air, and keep resin and hardener in separate leakproof tubs, locked away, out of reach of children, and apart from food. Write the opening date on every container and check the shelf life on the label or in the technical data sheet; if you’re not sure, do a test pour with about 3.5 oz (100 g). Never transfer resin or hardener into other containers, and certainly not into food packaging.

Source: Safe Resin Art, chapter 10, pages 120 to 121.

Liquid leftovers of resin and hardener are hazardous waste; correctly mixed, fully cured, and cooled epoxy resin can usually go in the regular trash where local rules allow. Take liquids to household hazardous waste collection (US: HHW drop-off site or collection event; UK: household waste recycling centre), never to the trash or down the drain, and bottles with liquid residue go there, too. Mix small leftovers in the correct ratio and let them cure in an open silicone cup somewhere safe and ventilated; don’t do this with larger amounts, which can get very hot. Never seal resin that is still warm or reacting.

Source: Safe Resin Art, chapter 10, pages 126 to 127.

If you sell in the EU under your own name, the General Product Safety Regulation (GPSR) has treated you as the manufacturer since December 13, 2024, however small your business. Before you sell, you carry out an internal risk analysis, including the materials you embed, and keep technical documentation for ten years. Each product needs an identifier such as a batch or serial number, your name, your postal address, and your email address. Occasional, noncommercial hobby sales and original works of art may be exempt, depending on the case, but coasters, trays, or jewelry are very likely covered. The law also requires you to know your suppliers and be able to name them; strongly recommended are working only with products that have a complete safety data sheet and noting which materials went into each piece. In the US, product liability is a matter of state law, and the Consumer Product Safety Commission (CPSC) oversees consumer products; in Great Britain, the General Product Safety Regulations 2005 apply.

Source: Safe Resin Art, chapter 9, page 112.