Is Resin Flammable? [Epoxy, Polyester]

Whether you are into arts and crafts, or making furniture or flooring, you probably use some form of resin. 

It’s a very versatile substance that is a staple when it comes to all kinds of art - molding, casting, jewelry making, woodcrafting, etc. Odds are that if you like to spend your time doing all of these kinds of activities, you probably have containers of resin lying around your home or studio.

Is All Resin Flammable

But have you ever stopped and considered how much of a fire hazard is resin? 

With all these containers full of resin stored around your property, you need to know what kind of danger they pose if a fire were to break out.

Understanding resin will allow you to make informed decisions on how you handle and store this adaptable and useful substance, potentially saving you a lot of hassle and stress.

Here is all the information you need to understand what resin is and how dangerous it could be if exposed to flames and heat. 

What Is Resin?

Resin is a material that can be used for many different purposes but is most commonly used for arts and crafts projects, and constructing and fixing furniture. 

There are different types of resin including epoxy resin, casting resin, and polyester resin. Each has different chemical formulas with different properties, making each one unique and perfect for different uses, but the most used and popular types of resin is epoxy and polyester resin.

The difference between the two is that epoxy is more resistant to wearing and cracking, while polyester is more fragile. 

Due to its use in crafts and furniture construction, both resins are easily available to purchase so people can use them to aid in creating products for their small businesses and hobbies.

This means that both epoxy and polyester resin can be easily found in homes, stores and studios across the United States - but which one is the bigger danger to you?

Is Epoxy Resin Flammable?

Epoxy resin is considered a flammable polymer unless it has been cured with fire-resistant chemicals. Then, epoxy resin is actually considered non-flammable and is unlikely to catch fire. 

You may have seen epoxy resin start to smoke when it is curing, and this leads people to believe that epoxy resin is highly flammable when the opposite is true - this ‘smoke’ is just actually evaporating gasses rather than gases emitted from combustion.

Epoxy resin does reach high temperatures during its curing process but not enough for the resin to ignite and catch fire. Curing epoxy resin is no more on fire than boiling water.

Once the epoxy resin has finished its curing process, it is actually non flammable. 

When epoxy resin is used as an adhesive and is used to bond wood, the wood itself can catch fire when exposed to a flame - but it won’t burn hotter or quicker due to the application of epoxy resin.

Also, applying epoxy resin to wooden furniture will not make the wood fire resistant. Wood will still burn if exposed to flame, and so will the epoxy resin - but neither will combust spontaneously by itself.

However, it still can catch fire if heated up enough - but this requires intense heat. Epoxy resin will not combust all by itself and would need a lot of exposure to heat and flame in order to catch fire, just like pretty much everything else.

The epoxy resin can melt in temperatures as low as 150 degrees Fahrenheit, but this will not help the wood burn more fiercely. 

Epoxy resin, once cured, is relatively safe and no more dangerous than wood. 

Is Polyester Resin Flammable?

Polyester resin is flammable before it is cured, and even after curing.

This is because polyester resin has a low flashpoint of around 90 degrees Fahrenheit, classing it as a flammable material. For a substance or liquid to be classed as flammable, it requires a flashpoint of below 100 degrees Fahrenheit.

The rule of thumb regarding flashpoints is that the lower the flashpoint, the easier it is to ignite the substance, and so the more cautious you must be when handling said substance. 

As polyester resin has a flashpoint below 100 degrees Fahrenheit, this means it can ignite easily at ambient temperatures and requires you to be vigilant and careful when handling polyester resin. 

So to sum it up, yes - polyester resin is indeed flammable. 

How To Handle Polyester Resin

There are many safety precautions you should have in place when working with polyester resin, and not all of them have to do with preventing a fire.

Polyester resin is very toxic in its liquid form, so you should always wear protective eyewear like goggles and protective clothing like gloves when handling polyester resin.

Keep the room you are working in well ventilated to prevent you from inhaling any toxic fumes as well, especially during the curing process. 

As for avoiding a fire involving polyester resin, you should not work with polyester resin anywhere where there is an open flame or smoke. This may come into contact with the vapor produced by polyester resin and ignite them.

When you are not working with polyester resin, make sure that you keep the resin in a closed container and store them in a cool dark place away from heat or direct sunlight. 

If polyester resin is involved in a fire, the best thing you can do is evacuate the premises and call 911. Trained firefighters will arrive on the scene and extinguish the fire without you having to put yourself in danger.

If you do have a fire extinguisher at hand, specially a Class B fire extinguisher, then you can use that to try and put out the fire yourself but do not put yourself into any unnecessary danger.

Class B fire extinguishers contain carbon dioxide to smother the flames and cut off its oxygen supply, thus extinguishing a fire involving polyester resin. 

However, as long as you handle polyester resin with care and do not use or store it around any open flames or heat sources, then a fire should not break out. 


So - is resin flammable?

It all depends on the resin and what state it is in. Uncured resins are indeed flammable and need to be handled with caution and care. 

However, once epoxy resin is cured, it is no longer flammable and is instead fire resistant. This does not mean that epoxy resin cannot catch fire - if you apply epoxy resin to a wooden bench and set the bench on fire, the whole thing will burn.

However, this is because wood is a flammable material and will burn when exposed to flames and heat. 

Cured polyester resin, however, has a flashpoint around 90 degrees Fahrenheit and so, it can ignite at ambient temperatures. This makes polyester resin a flammable substance. Polyester resin should be handled with care, and not used nor stored around any flames or heat sources.

If a fire does break out involving polyester resin, evacuate and call your fire department, or use a Class B fire extinguisher to extinguish the fire. 

With all this in mind, you can now use this information to choose the right resin for you and know how to properly store it to save yourself any stress and hassle involving resins and fire.