Is Polyurethane Paint Flammable?

When it comes to finishing a surface, you need to consider several factors such as the flammability of the paint. Especially if you plan on painting a fireplace or the kitchen.

So you may be wondering – is Polyurethane paint flammable? Here is the answer to that.

Polyurethane paint is flammable because the material used in making the paint is organic. This means that polyurethane will catch fire if exposed to a naked fire or extreme heat.

However, polyurethane can be protected by building structures around the poly finish to prevent fire damages.

So how do you protect poly from catching fire? Is dried poly coating flammable? And does poly make wood more flammable?

There is more to know about polyurethane and its flammability. Luckily, this post digs right into the topic. So keep reading to find out more.

How Flammable Is Polyurethane?

Polyurethane is highly flammable. When exposed to a heat source of about 105 degrees Fahrenheit, most poly finishes will vaporize and ignite. The poly finish will burn and produce a host of toxic substances like carbon monoxide when exposed to a sufficient heat source.

Polyurethane is as flammable as other organic materials like cotton due to the organic composition of the finish. Most polyurethane finishes have a flashpoint between 100 degrees Fahrenheit and 120 degrees Fahrenheit.

On average, polyurethane has a flashpoint of about 105 degrees Fahrenheit. This means the polyurethane will ignite if exposed to a heat source of 105 degrees Fahrenheit which is not that high when compared to other finishes.

Water-based latex paint for instance has a flashpoint of 200 degrees Fahrenheit. That means the paint has to be exposed to a heat source of over 200 degrees Fahrenheit before it can ignite and burn. When you compare this to the 105 degrees Fahrenheit flashpoint of polyurethane, you can see how flammable polyurethane is.

Polyurethane is regarded as a very flammable material. This is because the finish has a high level of organic materials in its composition and organic materials ignite easily.

Poly will start to burn when exposed to heat over 105 degrees Fahrenheit. If the heat source is maintained, the vapor being produced will ignite causing the poly to revert to its liquid form. When this happens, toxic fumes and compounds like carbon monoxide will be released into the air causing a mix of unpleasant smells and toxicity.

But if polyurethane is flammable, does this mean polyurethane coating is also flammable? Let’s find out.

Related Read: Can Latex Paint Catch Fire?

Is Polyurethane Coating Flammable?

Polyurethane in a liquid state is very flammable, but is polyurethane coating flammable?

Polyurethane coatings are flammable but the flammability reduces as the coating dries. This is because the solvent and chemicals causing the high level of flammability are being evaporated.

Polyurethane coatings are still flammable especially when the coating is still drying or curing. A fresh coating of polyurethane finish is still as flammable as liquid poly because the solvent and chemicals in the coating haven’t been evaporated yet.

However, when the poly coating has dried, the level of flammability reduces and the coating is considered safe.

The flammability of polyurethane coating especially fresh poly coating is why painters take caution to apply extra layers of protective coats on the poly coating. This is to prevent it from burning especially if the poly coating was applied close to a heat source strong enough to ignite the poly.

Polyurethane coatings after being applied on a surface are still flammable. Though the flammability is not as high as liquid poly, the finish can still ignite if exposed to a heat source that is strong enough.

In building and construction, the use of poly is sometimes regulated by fire codes and regulations. Professional painters also advocate for the use of fire suppression systems when poly is used.

Another thing to know is if polyurethane is still flammable when dry. Let’s take a closer look at that.

Is Dried Polyurethane Flammable?

Dried polyurethane is flammable but not as flammable as liquid polyurethane because the chemicals and solvents in the polyurethane have been evaporated.

The main reason why polyurethane is highly flammable is because of the organic and chemical composition of the finish. Poly is made from a combination of various organic and chemical compounds like polyol (alcohol).

The presence of these chemicals and compounds in the poly makes it highly flammable in its liquid state. But once the poly has dried completely or cured, the flammability of the poly is reduced drastically because the chemicals and solvents causing a high level of flammability have been evaporated.

However, the fact that the solvent and chemicals have been evaporated doesn’t mean that the poly isn’t still flammable. Poly when dry mirrors the qualities of plastic. When exposed to sufficient heat, the poly finish even when dried will begin to produce toxic fumes. If the heat source is maintained at the current temperature, the poly can ignite and will start to burn.

Related Read: Does Polyurethane Expire?

Does Polyurethane Make Wood More Flammable?

If polyurethane is flammable, does that mean that it can burn the wood that it is painted on? No.

Polyurethane doesn’t make wood more flammable than it already is. This is because the wood and the polyurethane finish have different flashpoints and auto-ignition levels. Wood will only burn if exposed to a naked flame but poly can burn if there is sufficient heat.

Most people believe that painting their wood with a poly coating makes the wood more flammable. This is a myth about polyurethane. Poly doesn’t make the wood more flammable because wood and poly have different flashpoints. The flashpoint of a material is the lowest temperature that which the material can ignite and then start to burn.

Wood doesn’t burn unless it is exposed to a naked flame. Even if the heat is increased in the room, the wood wouldn’t burst into flames. The wood will only burn if the polyurethane bursts into flames and poly rarely burst into flame.

The poly can melt and produce fumes in the air but this isn’t enough to make the wood underneath burn. You might just notice burn marks and scars on the wood but it wouldn’t catch fire unless the poly finish on it is in flames for an extended period.

For finished wood to burst into flames, the wood had to be exposed to a naked flame for an extended period. The finish on the wood might start to melt and produce fumes but the wood underneath wouldn’t burn unless the poly on it is burning.

In most cases, the poly would have finished burning before the wood even catches fire. This is because the poly coating is usually just a few inches thick so it would burn quickly if it catches fire.

Is Polyurethane Plastic Flammable?

Polyurethane plastic is highly flammable because of the chemical composition of the material. The low density, porosity, and chemical nature of polyurethane plastic make it highly flammable.

Polyurethane plastic is often referred to as polyurethane foam. Plastic refers to the plastic polymers that are included in the chemical composition of the poly. Alongside the plastic polymers like diisocyanates (TDI and MDI), polyol (alcohol) is also included in the composition of polyurethane plastic.

This high level of chemical content and alcohol coupled with the characteristics of the polyurethane plastic material makes it very flammable. Most plastic polyurethane products have the same flashpoint as liquid polyurethane.

Plastic polyurethane is used in various fields asides from painting. The material is used in the creation of furniture, carpets, interiors, and beddings. Poly plastic is very common due to its flexibility, water resistance, and durability. Plastic poly can be molded or structured to fit virtually any need for it.

But users of plastic poly know to always add a protective layer or build a protective structure around the material to prevent it from fire damages – especially if the plastic poly is used near a heat source or naked flame.

To protect polyurethane, a thermal barrier is usually installed near or around the poly. The thermal barrier can be made from different materials like plaster, masonry, concrete, or fire-resistant boards.

In some cases, the poly can be protected by adding a fire-resistant protective coating on the poly plastic after it has dried. The choice of the thermal barrier or protective structure depends on the building codes in the area and the cost.

Another thing that you should know is what happens when polyurethane burns as well as how to stop polyurethane fires. So keep reading.

Related Read: Is Polyurethane Waterproof?

What Happens When Polyurethane Burns?

When polyurethane burns, the poly goes through a process known as thermal degradation. Thermal degradation causes the poly material to produce fumes in the air that can be ignited. The poly material also forms carbon monoxide, hydrogen cyanide, and other toxic compounds upon combustion. But how the poly reacts while burning depends on the temperature.

When polyurethane burns, the poly releases fumes, and compounds but the compounds being released depend on the temperature at which the poly is being burned. If the poly is being burned at a low temperature, the poly releases hydrogen cyanide. If the poly is being burned at a high temperature, it would release nitrogen dioxide.

These fumes and compounds being released while the poly is being burned are toxic and very dangerouss. If inhaled, the compounds or smoke can cause damages to your body.

Polyurethane is a polymer and like other polymers, polyurethane undergoes thermal degradation when burning. Thermal degradation occurs when the poly is exposed to elevated temperatures. Thermal degradation is the breakdown of the materials and chemicals used in making the poly into smoke, gasses, and fumes.

When thermal degradation begins, the poly starts to burn and release smoke. This smoke being released contains toxic compounds like hydrogen cyanide and nitrogen dioxide that shouldn’t be inhaled. This is why firefighters use protective masks while dealing with poly fires.

But using protective masks is just the beginning while dealing with polyurethane fires. Let’s check out how to fight polyurethane fires safely.

How To Fight Polyurethane Fires?

No one plans to have a fire outbreak especially not a fire outbreak from polyurethane. But in the event of one, follow the tips below to battle the poly fire.

Use A Protective Mask

The first thing to do is to put on a protective face mask. You should ensure it’s a standard-issued face mask or breathing protection.

The last thing you want while battling poly fire is to inhale the toxic smoke being produced by the poly. If the fire is strong enough, the smoke being produced will severely damage you.

Use A Dry Powder Fire Extinguisher

To extinguish the fire, you should use a dry powder fire extinguisher. Don’t pour water on it because it most likely wouldn’t work.

The fire from poly is fueled by chemical compounds. Using water to extinguish such fire wouldn’t work as well as a dry powder fire extinguisher.

If you don’t have a dry powder fire extinguisher, you can stop the fire by pouring dry sand on the burning poly.

Aim For The Base Of The Fire

While using the fire extinguisher, you should aim for the base of the fire and not the top. When you extinguish the base, the fire stops.

The dry powder extinguisher will separate the chemical material at the base from the oxygen in the air through a thin layer of dust or dry powder.

Allow Proper Ventilation

When poly burns, it releases toxic compounds in the smoke. You should open all windows and doors while battling the fire to allow for proper ventilation. This prevents a build-up of toxic fumes in the affected room.

Final Words

Overall, polyurethane is a highly flammable substance. You should be careful while handling the poly to prevent accidents and fire outbreaks.

You should also protect poly coatings and layers after applying the poly by erecting fire barriers around the poly. This helps to prevent any outbreak of poly fire but in the event of a poly fire, follow the tips above to extinguish the fire.

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