You may be planning to sew your own coat and wondering is wool waterproof and would it be a good fabric choice. Wool has been deemed a wonder fabric for many years due to its many helpful characteristics. It is also important to know how to care for a fabric like this one.
Wool fabric is water-repellent but not necessarily waterproof. Natural wool fibers can be considered waterproof because of their lanolin content, but this quality is somewhat altered by the manufacturing process.
Although wool is water repellent, water molecules do still become trapped within its fibers. This process is actually helpful to you even though it may seem contradictory. In this article, we will break down the head-scratching properties of wool, the manufacturing process, how you can waterproof wool, and how to best care for the fabric.
When Is a Fabric Considered Waterproof?
When measuring a fabric’s protection against the effects of water, there are three levels to take into consideration. These levels are water-resistant, water-repellent, and waterproof. Many fabrics fall into the two former categories, and there are very few fabrics that are considered truly waterproof.
Water-resistant fabric can resist water to a degree. Oftentimes a fabric is water-resistant if the fibers are woven tightly together, causing the water to run off the fabric. If more pressure is applied, then the water will pass through the fabric.
This means that water can’t easily pass through the fabric. Water-repellent fabric contains a hydrophobic coating that can repel water, keeping it off of your skin.
This means that water will not be able to pass through the fabric. Usually, garments that are considered waterproof have been treated with a DWR (durable water repellent) and they may even have an additional layer of material for protection.
Is Wool Water-Repellent?
Taking these levels of water protection into consideration, where does wool fit in? Wool is water-repellent because of its natural hydrophobic coating, lanolin. Lanolin is a natural oil or wax produced from the glands of sheep or other animals that bear wool. This oil conditions their wool and also acts as protection from the rain since it repels water.
Wool was the popular choice of clothing amongst old Irish fishermen. Wives would knit sweaters (called ganseys), jumpers, and mittens from raw wool. The raw wool used back then still contained large amounts of lanolin which made these garments essentially waterproof. In addition to the lanolin content, the wool offered fishermen many other protective qualities that are still present in manufactured wool today.
Contrary to how you may picture them, the outer layer of wool fibers is shaped kind of like fish scales that shed water. The shape of these fibers, along with the lanolin content in wool, allows the wool to repel water. While this is true, one of the most puzzling qualities of wool is that it still contains some water inside its fibers, which actually help to keep you warmer.
Wool absorbs moisture, but it doesn’t absorb it. Adsorption happens when water molecules are trapped within the fibers of wool. This is different from absorption where water molecules pass through the fabric, making the fabric (and you) wet. Wool can hold up to 30% of its weight in water, and because it’s trapped inside the fibers, you don’t feel wet. This process of adsorption is pretty complex, but in short form, wool keeps an equilibrium between itself and the outside air in the same way as insulation in a building.
Wool can also generate heat. The water that is adsorbed condenses and releases heat. This is called hygroscopic insulation, and it’s why wool is able to keep you warm and dry even with water molecules trapped inside its fibers. Some even say wool can delay hypothermia for this reason.
All of these qualities work together to make wool water-repellent. The way it reacts with water is different from most water-repellent fabrics that only repel water on the surface of the fabric. No wonder wool is often called the wonder fabric.
Like many fabrics, the way in which wool is manufactured can alter some of these characteristics. The wool that was so successful for fishermen was raw and still contained a large amount of lanolin, making it more or less waterproof. The manufacturing process today removes a portion of lanolin through the cleaning process where wool is passed through various alkaline baths. This process is important so that dirt and sand are removed from the wool, but it does slightly decrease its ability to repel water.
The way that wool is woven will also change its level of water repellency. Wool that is woven very tightly will usually be more water-repellent than loosely knitted garments. The fewer and tighter the openings, the harder it is for water to pass through.
Can You Wear a Wool Coat in the Rain?
You can wear a wool coat in the rain. Wool fibers can soak up 30% of their weight in water without water passing through, meaning you should not feel wet. Wool is going to suck up some water molecules inside its fibers in order to reach equilibrium with the outside air, but it will actually keep you warmer through hygroscopic insulation.
You do need to be careful with wool containing a lot of water inside its fibers, though. Wool does lose about one-third of its strength in this state, so you should lay out your coat to dry rather than hanging it since this could create creases or holes.
There are limitations to the water-repellency of your garment if your fabric is woven with other synthetic fibers or if the weave is very loose. Also, remember that the water-repellency of your garment depends on how much lanolin is still present. This can be hard to determine.
How to Waterproof Wool Fabric
If you want to make your wool waterproof, you can add lanolin back into its fibers. You will want to make sure to get pure lanolin since that’s what was in your wool originally. Lanolin is available online and in many drugstores.
You will need:
- Lanolin wax
- Wool wash or laundry soap
- Fill a container (large enough for your garment) with warm water and add soap to loosen up the wool fibers.
- Determine the weight of your wool garment. (Yes, go ahead and step on the scale with your garment and subtract your weight from the total.)
- In a separate bowl, add ½ tablespoon of lanolin per pound of wool. Now add one cup of hot water and mix it until the lanolin is melted.
- Add the lanolin mixture to the large tub and mix all liquids.
- Fully submerge your garment in the lanolin mixture. Make sure there is enough water to cover your garment. Add more warm water if it is necessary.
- Let your garment soak for fifteen to twenty minutes.
- Carefully remove your garment (remember it is weaker when wet) and lay it flat to dry. Do not hang or wring your wool.
Before working with lanolin, you should ensure that you aren’t allergic by applying a small amount to your skin. Lanolin can cause allergic reactions in some people and could be extremely uncomfortable if your skin becomes irritated by your garment.You should also know that applying lanolin may slightly change the surface texture of your garment.
Is Boiled Wool Waterproof?
Boiling knitted wool shrinks it, pulling the fibers in close to each other. This can make wool more water-repellent than it already is. Shrinking wool will also help it retain heat for this same reason.
We discussed fishermen and their use of wool earlier. Fishermen used to wear boiled mittens because it pulled the fibers in closer, reducing the small spaces where water could pass through. But is boiled wool waterproof?
Since a fabric that is considered waterproof must not allow any water to pass through the fabric, even boiled wool would be considered water-repellent rather than waterproof. But oftentimes, that is all you need.
How to Care for Wool
There are a couple of ways that wool can be damaged. Keep these in mind when you’re looking for a storage place or handling your wool.
Direct heat can be very damaging for wool. It can change the shape of a garment because it alters the protein structures within the wool. Wool shouldn’t be ironed for this reason. It should be steamed instead.
If wool is exposed to bright light for a long period of time, it can become discolored. Garment bags can be helpful if your storage area is in the sun.
Insects are the biggest danger for wool. To keep insects from eating away at your garments, keep mothballs or cedar wherever you store your wool items.
Wool is naturally antimicrobial and stain resistant so you shouldn’t have to wash it as often. But when you do, use a detergent specifically for wool, choose a gentle cycle (some machines may even have a wool cycle), and only wash it in cold temperatures to avoid shrinking. Air dry your wool by laying the fabric out flat in its original shape. Placing your wool in the dryer may shrink it. You can also hand-wash your wool in a tub of water with wool washing liquid, but do not wring it as that can damage the fibers.
While wool is not waterproof, it is water-repellent due to its natural lanolin content and its scale-shaped fibers. It is possible to return wool to its original waterproof-like state by adding back the lanolin that was removed during the manufacturing process. Regardless, its ability to keep you warm by generating heat and adsorbing water helps make this fabric an excellent inclement weather choice.
Comment below if any of these qualities of wool surprised you. Also, let us know if you have ever added lanolin back into a wool coat, and tell us how it went. Be sure to share this article if you found it helpful. Thanks for reading!