Is Polyester Waterproof?

Is Polyester Waterproof

With monsoon being just around the corner, most people are soon going to shop for raincoats, waterproof jackets, backpacks, and whatnot. But when you’re in the market, you will find that there are many waterproof fabrics that make these apparel, such as nylon, polyester, vinyl, rayon, and others.

But are all these fabrics truly waterproof, as they’re advertised to be? What about polyester?

Is polyester waterproof? The answer to it is both yes and no. While in its truest nature, a single strand of polyester is waterproof, when woven together, pure polyester fabric is not 100% waterproof. A better term for these kinds of fabric is “water-resistant”. However, polyester can be made 100% waterproof by adding different kinds of coating to it. 

Are you wondering how the terms “waterproof” and “water-resistant” are different from one another? And how is polyester water-resistant but not waterproof? To better understand the answer to these questions, you’ll first need to learn more about what polyester is.

Don’t worry; in this article, we are going to answer all your doubts and queries about polyester and its capacity to resist water. 


What is Polyester?

Polyester Chemical Group

Polyester or Polyethylene Terephthalate (PET) is an artificial fiber that is made of two ingredients: purified mono-ethylene glycol (MEG) and terephthalic acid (PTA). These ingredients have been derived from the chemical reaction between water, air, and petroleum.

Most people wonder whether polyester is a natural or man-made fiber. Although polyester is known to occur naturally as well, the fiber that is widely used in the clothing and textile industry is synthetic polyester.

In this article, we are going to talk about synthetic polyester fabric.


Waterproof Vs. Water-resistant: what’s the difference?

At the beginning of the article, we mentioned how polyester fibers should aptly be called “water-resistant” instead of “waterproof”. Now, some people might assume that these two are interchangeable terms, but they’re more different than you’d think.

Waterproof fabric is a fabric that provides a complete barrier against water, like a plastic bag. On the other hand, the water-resistant fabric is a tightly woven fabric through which water cannot pass easily.

There is no fabric, be it natural or synthetic, that is fully waterproof in its original form; the ones that are fully waterproof have either been modified or blended to achieve it.

Now, you might think that waterproof clothing would be better than water-resistant clothing. However, if you look at them from a practical standpoint, you’ll find that water-resistant clothes are better.

Fully waterproof fabrics have no room for air to pass, making them less breathable. So, while they will protect you from the water on the outside, you are very likely to sweat on the inside.


Can polyester absorb water?

Polyester, on its own, doesn’t absorb water. For instance, if you leave a polyester thread out in the rain or pour water on it, it will remain unchanged.

However, when these threads are woven together, there are gaps in the weave through which air and water can pass.


Is polyester a good fabric for rain?

Polyester for rain

While polyester cannot block 100% water on its own, it is still water-resistant enough to be considered helpful in the rainy season.

In addition to being water-resistant, it is also durable, wind-resistant, mildew-resistant, tear-resistant, and stain-resistant, which makes it an ideal choice for rainy days.

These qualities of the polyester fabric are the reason why it is the most popular material for raincoats, windbreakers, tents, shower curtains, and bean bag chairs.


Can you make polyester fabric waterproof?

So far, we’ve learned that polyester, in its original form, is highly water-resistant but not fully waterproof. But did you know that these fabrics can be made fully waterproof?

There are several methods to make polyester fully waterproof, and we are going to discuss these methods in the section.

1. Creating high-denier polyester fabric

How many of you have heard of the term “denier” before? It is a unit of measurement used to determine the thickness of fiber (the mass of its threads in gram per 9,000 meters of fiber).

The more closely a fabric is woven, the higher its denier count will be. And as we’ve already discussed, close-knit fabrics have fewer gaps for the water to pass through.

This means that the polyester fabric that has a higher denier will be more water-resistant than a fabric with a lower denier.

2. Layering

Another method of making polyester fully waterproof is by adding multiple layers of fabric to it.

While it is difficult to layer polyester-based clothes like raincoats ad wind-breakers, layering works perfectly on bean bag chairs.

3. Coating

While increasing the denier of polyester fabric and layering can only work in certain conditions, the coating is the most efficient method of making it fully waterproof.

It refers to adding another protective seal or coat on the fabric to increase its water-resistant, making it 100% waterproof.

If you already have a polyester tent or backpack that you want to make fully waterproof, you can purchase silicone sprays to coat them. A little bit of research online will tell you exactly what you should buy.

Additionally, there are also several kinds of polyesters that are made waterproof with special coatings. Let’s take a look at some of these:


Types of polyesters 

Polyurethane Laminate (PUL)

Polyurethane Laminate is a fabric that has a laminated layer fused atop a thin-knit polyester fabric. PUL can be considered stretchable to some extent, is fairly breathable, and is compatible with machine wash.

PUL fabrics are most commonly used in manufacturing shower curtains and sports gear.

PUL Polyester

Thermoplastic Polyurethane (TPU)

Thermoplastic Polyurethane is manufactured by bonding the polyester fabric with a polyurethane membrane. While it is similar to PUL, it has a softer texture and is generally considered to be less durable than the latter.

TPU is used to make survival suits, drysuits, and other safety wear. All garments made from TPU are UV-resistant.

TPU Polyester


PVC-Coated Polyester

Out of all the three coated polyesters mentioned here, PVC-coated polyester displays the highest water resistance and is totally waterproof. In this material, polyvinyl chloride is coated to the back of the polyester fabric, making the final product a little stiff but 100%re waterproof.

As expected, this polyester has the highest denier and is also very durable. PVC-coated polyester is used to make luggage bags, banners, and upholstery.

PVC Coated Polyester


What are polyester blends? Are they waterproof?

Like most of the other fabrics, polyester fabrics are also blended with other fabrics to produce different products. But are any of these blended fabrics waterproof? That’s what we’re going to find out in this section.

Let’s begin by taking a look at some of the most popular poly-blend fabrics:

Poly-spandex blend

Also referred to as “elastane” or “lycra”, spandex is a synthetic fiber that is popular for its elasticity. A blend of polyester and spandex results in fabric that is soft to touch is flexible and durable. In terms of water resistance, these blends can work effectively.

Poly-spandex blend is often used to make activewear. If you happen to have yoga pants, they’re most likely made of the poly-spandex blend.

Poly-cotton blend

While cotton fabrics are known for their comfort, blending them with polyester adds to their durability, making them more tear-resistant.

Poly-cotton blends are also cheaper than pure cotton fabric, which is another reason for their popularity. However, due to the presence of cotton, this blend is not good at water resistance.

Poly-cotton blends are commonly used to make t-shirts, skirts, and pants.


Conclusion: Is polyester waterproof?

In this article, we have learned that polyester is an artificial fiber that has a high capacity for water resistance. However, contrary to popular belief, it is not fully waterproof. When the polyester fibers are woven into a fabric, the gaps between the weaves can allow water to seep in under extreme circumstances.

And although polyester might not be waterproof in its original form, there are many ways of making it waterproof, some of which have been mentioned in this article.

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