Is Polyester Water Resistant Or Waterproof? (Explained)

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Yes, polyester material is 100% water-resistant and waterproof though polyester fabric does not exhibit waterproofing qualities due to the way the polyester fabric is manufactured still the polyester fabric is water-resistant.

However, there are ways by which polyester clothing or accessories can be waterproofed.

If you’re a bit more curious, continue to read this article because here we are going to cover every minute technical detail to answer the water-resistant capabilities of polyester fabric.

Is polyester water resistant? (Technically explained)

Please wear a polyester garment and feel its breathability.

If airflow is happening properly then that polyester garment is less water resistant. But, if it is less breathable meaning it has reduced air permeability which in turn makes it better on resisting water.

Please look at this from a wide perspective.

If we just see the polyester in its core, Polyester is a waterproof material because the word polyester means a long chain of polymers consisting of the ester group.

While polyester fabric can be derived using various chemicals but in the current time, PET (Polyethylene Terephthalate) is the most commonly used plastic to manufacture not only the clothing fabric but the majority of plastic bottles.

Now tell me, is your plastic bottle or your coca-cola bottle not waterproof? Obviously, it is completely waterproof.

Is there any other factor? Yes in addition to plastic as the main ingredient in polyester clothing, the material itself is hydrophobic in nature, meaning it fails to mix with water and thus repel it rather than absorbing it.

However, it is not entirely hydrophobic because it demonstrates a bit hygroscopic nature which causes it absorbs a small percentage of water molecules.

The other important factor is that polyester does not absorb moisture but absorbs the oil which makes it the perfect fabric when it comes to water-resistant finishes.

So, it is the polyester fibers and threads in your so-called polyester clothing that are considered waterproof but when the threads are woven together the garments are not waterproof at all but offer great water resistance.

There’s a very common myth that if you increase the polyester thread count the clothing will exhibit better water repellency.

Ok, that plays a role, but other factors like yarn production technology, yarn diameter, twist, hairiness, fiber firmness, polyester fiber cross-section, yarn packing density, the filament in the yarn are also important factors.

A general rule of thumb is: if your polyester clothing is tightly woven and if it is made from microfilament polyester yarn then the dimension of pores between the fibers, inside the yarn decreases. In simple it results in smaller size gaps to give the maximum water resistance.

Because now the water will need high pressure to penetrate these small gaps.

But, you should also be aware that if you buy a tightly woven, thick fabric and lower filament fined polyester cloth then you will compromise the breathability of that entire piece of cloth because of reduced air permeability.

Although, in terms of polyester tents it is good to get one with high yarn density so that the dimensions of the pores reduces to give better wind protection along with rain protection.

Is 100 polyester waterproof?

The 100% polyester material without any mixture is waterproof because it is continuous homogenous material but the 100% polyester fabric is not entirely waterproof.

As I already explained, the pores between the fibers and inside the yarn will decide the waterproofing of it.

So when it comes to 100% polyester fabric, it is obvious that the pure polyester threads are woven together & if they have higher filament fineness will result in increased fabric density and decreased porosity. Meaning the less possibility of water slipping in.

Porosity is the ratio of the total amount of void space in a material to bulk volume occupied by the material

Thus if you want a better water resistance then you should go with 100% polyester that is tightly woven and if the number of filaments in a yarn of a given linear density increases the surface area of all the polyester fiber will increase and in a closely constructed polyester fabric the gaps between the fibers get smaller which will result in greater water repellency.

This is something I don’t think is very practical that’s why if you’re going for 100% polyester-made clothing then you should look for waterproofing coating on it.

Like Patagonia, which mostly uses 100% recycled polyester, also features a water repellent coating like DWR (Durable Water Repellent) to enhance the water resistance.

In fact, in most of their 100% polyester jackets, they also use H2NO or gore-tex waterproofing layers beneath the polyester layer to make it entirely waterproof.

Is spun polyester waterproof?

No, spun polyester is not waterproof instead it is water-resistant.

First of all, the main ingredients behind the spun polyester are not any different from what is used to manufactured normal polyester fabric.

But because spinning the polyester fibers after cutting them into short fiber and merging all the short pieces gives them a soft but smooth texture,

And because of this, the pores are naturally smaller than the normally produced polyester fabric that’s why it offers good water resistance than any other polyester fabric, will not be completely waterproof unless it is treated with coating, membrane, or has given technical finishing.

Is 600d polyester waterproof?

No 600d polyester is not waterproof but it is more water-resistant than 500d polyester or 300d polyester.

I will not waste your time telling you that D means denier and all the basics.

Let’s do the main course.

Denier or ‘D’ is a measurement unit for fabric that is there to measure the linear mass density of fibers, it is the mass in grams per 9000 meters of the fiber.

In general, the higher the number of deniers, the thicker the fabric will be.

Now, if it is 600d polyester then it means it is thicker than the 300d but it is comparably thinner than 1000D.

Now FYI, the thicker the fabric is, the smaller the size of pores between the fibers will be, and thus for 600d polyester water molecules takes more time and need higher pressure to pass through these tiny pores.

So practically, a 600d polyester backpack can be used for some time in mild rain and snow.

But, a waterproofing coating is a must when it comes to using a 600d backpack in heavy rain and high humidity area because the water will penetrate the fabric much sooner in high pressure.

Can you waterproof the polyester fabric?

Yes, the polyester fabric can be waterproof completely by using some practices we are going to tell.

If you’re asking for polyester material then you do not need to use anything because polyester is derived from waterproof plastic.

How Waterproofing Of Fabric Tested: The water repellent properties of the coated fabrics were evaluated by measuring water vapor permeability, spray test,contact angle, hydrostatic pressure and rain test

Source: ijirt.org

So, let’s talk about the possibility of making polyester fabric completely waterproof.

How to waterproof the polyester fabric?

There are various ways by which a polyester fabric can be waterproof.

As we know from our previous discussion that the polyester material is waterproof but the polyester fabric is water-resistant and not consider waterproof because of the pores between the fibers.

So, here we have to treat it with a waterproofing membrane to close the gaps between the fiber.

Nonetheless. if your activities do not oblige you to stay in heavy rain for a prolonged time then you can go with polyester fabric that has DWR (Durable Water Repellent) coating on it. In a sense, DWR boosts the water-resistant ability of polyester garments.

PVC (polyvinyl chloride) and PU are some of the most popular chemicals to waterproof the polyester fabric but the main problem is that you’ll end up with a fabric that performs very little to no breathability.

That is why a PVC waterproofing polyester is good to use in tents and other materials that demand a great level of waterproofing and do not care for breathability.

But, PU (polyurethane) coated polyester clothing is best in terms of waterproofing polyester fabric yet allows airflow (can be seen in activewear and outdoor clothing).

However, to make the outerwear like jackets entirely waterproof and at the same time allow proper breathability and sweat to escape, nowadays, outdoor clothing companies like Patagonia, Arc’teryx. Columbia and North face use technical fabrics like Gore-Tex, OutDry, H2NO, Omni-Tech, etc as a waterproofing membrane with polyester for rigorous outdoor activities in heavy rain and snow.

Does polyester blend plays any role in water resistance?

Yes, the polyester blend is water-resistant but this is because of polyester itself and not the blended fibers like cotton.

However, the water-resistance capabilities of polyester can be enhanced if it is blended with other good water resistance fibers like wool or nylon.

The major benefit of buying poly blend garments is its super-absorbency, meaning polyester microfibers can absorb over 7 times their weight in water.

And when blended with natural fibers like cotton it increases the drying time.

According to research, polyester dries one-third time quicker than ordinary fiber.

Conclusion

I hope now you have a clear understanding of polyester and its water-resistance and waterproofing capabilities and possibilities.

So next time when you see 100% polyester or poly blend in any garment then you can be pretty confident that it will have good water resistance compared to other natural fabrics but the polyester shirt, jacket, or backpack will not be entirely waterproof unless it has TPU, PVC coating or has waterproofed fabric like Gore-Tex.

However, polyester material, threads, or fibers are waterproof in nature but when they are woven together leave tiny holes between the fibers which allow the water to penetrate from these air gaps.

Though the smaller the size of pores between the fibers and inside the yarn, the more water-resistant the polyester fabric will be.

Read Also: Can polyester keep you warm?

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