Breathable Fabric… How Do You Know if a Fabric is Breathable?
What Makes a Breathable Fabric?
We all know that our skin does not breathe air in and out…so what are we talking about when we say something is breathable?
Breathability refers to the process of moisture vapour (sweat) moving through a fabric to the outside. It’s a fabric’s ability to maintain the balance between the moisture contained in the fabric itself and the air around it. Fabrics that constantly absorb but don’t release humidity are non-breathable.
The reason moisture management is crucial for breathability is because evaporation assists the body to cool.
- Breathability is the way a material dissipates the wearer's body heat
- The most important factors that contribute to breathability is the construction of the fabric, it is not the content! Content matters only when the construction of the fabric yarns allow sufficient air flow.
An example of this is a very heavy cotton knit sweatshirt. It would be very uncomfortable to go running on a hot day without overheating even though many believe cotton to be a breathable fabric.
- 👀 For the purpose of this blog, we will not be dealing with Waterproof Breathable Shell Fabrics. They are quite complicated and require their own article! Watch for our new blog on Breathable Outerwear fabrics coming soon!
Is Polyester a Breathable Fabric?
The answer may surprise you!
It is a common misconception that all Polyester is non breathable. In fact, some of the most breathable, moisture-wicking fabrics are in fact polyester! How can this be?
PET material, another name for Polyester in its raw form is not breathable at all. But Polyester fabric can be constructed in a way that allows breathability.
In the past decade new manufacturing techniques have designed knit and woven fabrics to effectively move moisture along the yarn and through the fabric to allow moisture to escape. Evaporation is a result of air contacting those moist fibers, which not only keeps you dryer, but also cooler. So, when air and moisture move freely it makes the fabric breathable.
The two factors that most affect comfort levels are climate (temperature )and activity of the wearer. We don’t notice how breathable our clothing is when we are sitting around watching TV…but try running on a hot day and you’ll soon discover if your shirt is breathable!
If you love details and want to read about standard testing methods, the Hohenstein test is explained.
Is Nylon a Breathable Fabric?
Nylon is a synthetic material made from polymers, which allows air to pass through its fibers. However, along with other synthetic fabrics it must be constructed (knit or woven)to enhance breathability.
Regardless of fabric content it is the thickness and mechanical construction of the fabric that most affects breathability.
If Nylon is not knit to enhance breathability it will be hot and inefficient!
But, the same is true with any fabric, even linen or cotton.
A light, loosely woven natural fabric would be the hot-weather choice of those who are not highly active. But you would not find anyone wearing heavy, densely knit cotton in the same weather or they would overheat quickly!
What are the Most Breathable Fabrics for Hot Weather?
Here's a breakdown of common fabrics, each with its own features. Keep in mind that these characteristics can vary within each fabric type, and manufacturers may blend fabrics or apply finishes to alter their performance.
- Cotton
Cotton comes in various types and is commonly used for summer clothing that isn't designed for active use. As discussed earlier, even natural fabrics must have a light, looser construction to be comfortable in heat. If you were to wear a heavy cotton knit shirt and start to exercise, you would soon overheat. A lightweight loose cotton shirt would be cooler, but would retain sweat and take a long time to dry. So once again, we must understand that the construction and weight of the garment is key to how breathable it is.
Advantages: Soft, durable, versatile, and easy to care for. Perfect for warm weather when activity level is low
Disadvantages: Absorbs moisture instead of wicking it away, making it less suitable for sweating. Lacks Sun Protection in lighter weights.
- Nylon and Polyester
These synthetic materials are often found in activewear.
Advantages: Moisture-wicking, quick-drying, and resistant to pilling and abrasion. Can be highly sun protective depending on style as well as highly breathable IF specially designed for that purpose. Wrinkle-resistant.
Disadvantages: can retain odors (exceptions are high performance knits with effective antimicrobial treatments such as Chitosan or Silver)
- Rayon
Rayon, also known as viscose or lyocell, is a processed plant-based fabric that is often blended with other materials.
Advantages: Silky feel, moderate breathability, drapes nicely, and dries quickly.
Disadvantages: Doesn't wick moisture as well as synthetics, prone to wrinkles, and many rayon fabrics require dry cleaning.
- Linen
Derived from flax plants, linen is popular for casual summer wear.
Advantages: Very durable, easy to care for, and typically offers excellent breathability due to its large fibers and open weaves.
Disadvantages: Absorbs moisture like cotton, wrinkles easily, and not ideal for sweating.
- Silk
Silk is commonly used in underwear and upscale casual wear.
Advantages: Luxuriously soft, lightweight, and breathable.
Disadvantages: Fragile, not great at wicking moisture, retains odors, and usually requires hand washing.
- Merino Wool
Although often used in winter wear, merino wool can be suitable for summer clothing. Modern versions are soft compared to older wool types.
Advantages: Fairly breathable and available in lightweight styles for summer wear; doesn't hold odors like synthetics.
Disadvantages: Less durable than cotton, nylon, and polyester fabrics.
NOTE: Polartec Power Wool offers all the advantages of 100% Merino but is more durable and dries faster.
So What’s the real story?
There is much misinformation on the internet about breathable fabric.
Many people believe that only natural fabrics are breathable, and that polyester is hot and uncomfortable.
The truth is this...it depends! Natural fabrics are lovely and breathable when they are loosely woven or knit. But, when a person is active or sweating, Cotton or Linen can be very uncomfortable as it does not dry quickly. Also, loosely knit fabrics are not very sun protective, as the harmful rays can get through the openings of the weave.
Polyesters, especially poorly designed fabrics, can be hot and sticky...
However, well designed polyester or nylon knits can enhance moisture movement, dry faster, and offer high sun protection. Many also boast superior antimicrobial treatments for odor control.
Make an educated choice based on what you intend to be doing while wearing the garments you make.
Conclusion...
If you are doing sedentary activities and just want to stay cool, a number of choices are available to you.
If you need added Sun Protection, we recommend
For strenuous activities where you will be sweating and potentially overheating we recommend
Polartec Delta (summertime only, not for winter because it is also a Cooling Fabric)
For all season breathability, we especially love Polartec Power Wool Silkweight.
Ask for Advice!
There are many considerations when choosing breathable fabric. We love to help, which is why we have a Facebook Group. If you ask in our group, be specific about your needs. We will try to make suggestions that will help you make a great choice. We are always happy to chat in the group, where others can learn from the answers! Our Facebook group is Sew Inspired by Discovery Fabrics. Join us!
