If you’re looking for the safest bedding material, wool is easily the best choice. It traps heat well and absorbs moisture well. But what about fire? Is wool fire-resistant?
Yes, wool is naturally fire-resistant to a certain extent. It has a high ignition temperature of 570°C-600°C. Even if it catches fire, wool will self-extinguish when the flame source is removed. Moreover, it can absorb moisture and trap heat, which reduces the spread of fire.
Remember, wool can still burn if exposed to a flame for a sufficient amount of time, especially if it’s not treated with additional flame retardants.
Keep reading to know more about the fire resistance of wool.
How Wool Is Fire Resistant Compared to Other Fibers?
Wool shows the highest fire resistance compared to commonly used fabrics such as cotton, nylon, polyester, and rayon. All these textiles must be treated with a fire retardant to make them resistant to fire.
Wool is different in this case as it’s naturally fire-resistant and doesn’t require any treatment.
Although synthetic fibers are resistant to high temperatures, they start melting at low temperatures. Nylon fabrics melt at 160°C to 260°C whereas polyester will melt and drip at 252°C to 292°C.
Wool doesn’t have any such issues as it can withstand higher temperatures without melting or dripping. Below are the fire-resistant and melting temperatures of wool and other textiles:
| Fiber Type | Ignition Temperature in °C | Melting Temperature in °C | Limiting Oxygen Index (%) |
| Wool | 570-600 | Doesn’t melt | 25.2 |
| Cotton | 255 | Doesn’t melt | 18.4 |
| Rayon | 420 | Doesn’t melt | 19.7 |
| Polyester | 485-560 | 252-292 | 20.6 |
| Nylon | 485-575 | 160-260 | 20.1 |
Key Factors Regarding Flame Resistance of Wool
As you might know, wool is a natural animal fiber collected from sheep, yak, camel, or goats. Therefore, the physical and chemical properties of wool are different from other fabrics.
Here are the key points about the flame resistance of wool −
Protective Cuticle Layer of Sulphur
The fibers of natural wool are produced from keratinized cells. In the center of wool fiber, its elongated cortical cells are protected from harsh environmental conditions by a layer of protective cuticle cells.
As this layer contains a high amount of sulfur, it doesn’t allow the fabric to react easily with environmental oxygen. Hence, wool fibers don’t ignite at high temperatures.
Insulating Layer of Pyrolyzed Materials
All the wool fibers are held together by a crosslinked cell membrane complex. If the temperature starts to rise, this structure changes its form and provides an additional layer of pyrolyzed material.
It works as an insulator that separates both oxygen and heat from the wool fiber. This way, wool doesn’t spread the heat, so the flame is easily extinguished.
Is Wool Fire Retardant?
Wool is considered fire-resistant rather than fire-retardant. There’s a notable difference between the two terms. Below are the definitions:
Fire Resistant
This term is used for materials that naturally resist high temperatures and doesn’t ignite easily upon coming in contact with an open flame. Fire-resistant materials can withstand heat naturally.
They don’t require any special treatment or protective layer. Wool is an excellent example of natural water-resistant fiber.
Fire Retardant
While wool is naturally resistant to fire, some fabrics are man-made from fireproof fibers. Fire-retardant fibers aren’t naturally resistant to high heat.
They are produced from other fire-resistant materials or have a protective coating. Therefore, wool is more of a fire-resistant fabric than fire-retardant.
How Does Wool Resist Fires?
As we’ve discussed, wool’s natural properties like cuticle cells, crosslinked cell membranes, and strong chemical bonds are responsible for its fire resistance.
Here’s how wool resists fire and high heat−
Heat Trap
Natural wool resists fire by trapping the heat inside the fiber. This is why woolen clothing doesn’t catch on fire as easily as cotton clothing.
Wool fiber also conducts heat slowly, which allows the wearer to stay warm even if the outer layer of clothing catches on fire. It’s the reason why winter clothes are wool made.
Fiber Protection
Thanks to the high surface area-to-volume ratio of wool, it resists fire by protecting the fiber from burning. The fabric is made up of individual fibers that are very thin and have a large surface area.
Therefore, the fibers allow it to trap a lot of air, which helps prevent the fire from spreading. Besides, wool fibers are high in nitrogen, which doesn’t easily react with oxygen. So, it requires a lot of oxygen to be able to burn the wool.
Fuel Barrier
Wool fibers effectively resist fire by acting as a fuel barrier. Typically, wool absorbs a lot of moisture from the environment, which makes it difficult to ignite. When that material is exposed to fire, the heat burns it and changes its form.
The burned wool fibers then form a protective layer that protects the rest of the garment from catching on fire.
Is There Any Flash Point of Wool?
Flash Point refers to the lowest temperature at which a flammable material produces vapor on its surface so that it easily ignites when exposed to an open flame.
This concept applies to materials that are volatile and have a liquid form, such as fuels, solvents, and some chemicals. As wool is a fire-resistant fabric, it doesn’t have any fixed flash point at which it starts to vaporize.
However, the flash point of wool is generally around > 1058 °F (> 570°C). Wool has no auto-ignition point, which means it does not ignite automatically. So you can use it without any fire-related safety precautions.
Frequently Asked Questions
1. What happens to wool when burned?
Wool is a protein-based fabric that doesn’t melt when ignited. Instead, it shrinks and releases a strong odor similar to that of burning hair. Finally, it produces a fragile, black, irregular bead that turns into powder.
2. What fabrics are the least flammable?
Among the natural fabrics, wool and silk are the least flammable. Almost all synthetic fabrics can withstand high temperatures. Nylon and polyester are the least flammable synthetic fabrics.
3. Is burning wool toxic?
No, burning wool produces non-toxic smoke. It doesn’t do any serious harm to the human body when inhaled. However, it still contains carbon dioxide and breathing in too much of it will irritate your lungs.
Wrapping Up!
In this write-up, we’ve answered a commonly asked question− is wool flammable? It takes about a thousand degrees Fahrenheit to ignite wool.
So, it doesn’t possess any fire hazards. However, the fire resistance of wool can vary depending on the specific type of wool, its thickness, and any treatments or finishes that have been applied to it.