Is PET Polyester Waterproof?

You might be wondering if PET polyester is waterproof. Well, the answer to this question is not as straightforward as you might expect. PET polyester is a commonly used material in various industries, but its waterproof capabilities can vary depending on various factors. In this article, we will explore the waterproofing properties of PET polyester and provide you with the information you need to know. So, let’s dive in and uncover the truth about whether PET polyester is truly waterproof.

What is PET Polyester?


PET polyester is a type of polyester fabric that is known for its durability, versatility, and resistance to wrinkles. PET stands for polyethylene terephthalate, which is a type of plastic made from renewable resources such as recycled plastic bottles. This fabric is commonly used in various applications, including clothing, home furnishings, and outdoor gear.


PET polyester has several properties that make it a popular choice for waterproofing applications. Firstly, it is highly resistant to tears and abrasion, making it suitable for outdoor use where the fabric may come into contact with rough surfaces. Additionally, PET polyester is known for its excellent strength-to-weight ratio, making it lightweight yet durable. Furthermore, this fabric is quick-drying, which makes it ideal for outdoor activities where moisture management is crucial.

Waterproofing in Textiles

Importance of Waterproofing

Waterproofing is an essential feature in textile materials, particularly those used in outdoor and water-related activities. The ability of a fabric to repel water and prevent it from penetrating the fibers is crucial in providing comfort and protection to the wearer. Waterproof textiles help to keep the wearer dry and comfortable, preventing the ingress of water, which can cause discomfort, skin irritations, and even hypothermia in extreme conditions.

Methods of Waterproofing

There are several methods of waterproofing textiles, each with its own advantages and limitations. These methods include chemical treatments, coatings, lamination, and the use of waterproof membranes. Chemical treatments involve applying a water-repellent finish to the fabric surface, while coatings involve adding a layer of a waterproof material onto the fabric. Lamination combines two or more layers of fabric, with a waterproof membrane sandwiched in between. Lastly, the use of waterproof membranes involves incorporating a thin, breathable, and waterproof layer into the fabric structure.

PET Polyester and Water Resistance

Understanding PET Polyester

PET polyester is inherently hydrophobic, meaning that it naturally repels water. This property is due to the chemical structure of the fabric, which allows water molecules to bead up and roll off the surface. As a result, PET polyester fabrics exhibit strong water resistance without the need for additional treatments or coatings. This makes PET polyester a popular choice for outdoor and performance clothing where water repellency is desired.

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Water Absorption

While PET polyester is highly water-resistant, it is important to note that it is not completely waterproof. When exposed to prolonged or heavy rain, water may eventually penetrate the fabric and cause it to become damp. However, the water absorption rate of PET polyester is relatively low compared to other fabrics, meaning that it will dry quickly once the source of moisture is removed.

Resistance to Water

PET polyester fabrics are known for their resistance to water, which means they can effectively repel water and prevent it from entering the fabric. This resistance is especially useful in rainy or wet conditions, as it helps to keep the wearer dry and comfortable. The water resistance of PET polyester fabrics can be enhanced through the use of additional waterproofing technologies, such as coatings or laminations.


While PET polyester offers excellent water resistance, it does have certain limitations. In extreme conditions, such as heavy rain or prolonged exposure to water, it may eventually become saturated and lose some of its water repellency. Additionally, PET polyester fabrics can become less effective in repelling water over time with repeated washing and wear. Therefore, it is important to regularly maintain and reproof PET polyester garments to ensure their continued water resistance.

Factors Affecting PET Polyester Waterproofness


The construction of PET polyester fabrics plays a significant role in their waterproofness. Fabrics with a tight weave or knit structure are generally more water-resistant than those with a looser construction. This is because a tight structure minimizes the gaps between yarns, reducing the chances of water penetration. Fabrics with a higher thread count or denser fabric construction also tend to be more resistant to water.


The finishing process applied to PET polyester fabrics can impact their waterproofness. Water-repellent finishes, such as Durable Water Repellency (DWR) treatments, can be applied to the fabric surface to enhance its ability to repel water. These treatments modify the surface tension of the fabric, causing water to bead up and roll off rather than being absorbed. Finishing techniques such as calendering or brushing can also improve the water resistance of PET polyester fabrics.


The dyeing process used on PET polyester fabrics can affect their water resistance. Some dyes and dyeing methods can reduce the fabric’s ability to repel water. This is because certain dyes can fill in the gaps between fibers, making the fabric less hydrophobic. Careful consideration should be taken when selecting dyes and dyeing methods for PET polyester fabrics to maintain their water repellency.


Coating is another method used to enhance the waterproofness of PET polyester fabrics. A waterproof coating is applied to the fabric surface, forming a barrier that prevents water from penetrating the fabric. The type and thickness of the coating can vary, with some coatings providing a breathable layer that allows moisture vapor to escape while preventing water from entering.


Lamination involves bonding a waterproof membrane between two layers of fabric, creating a multi-layered composite material. This process enhances the waterproofness of PET polyester fabrics by providing an additional barrier against water penetration. Laminated fabrics are often used in high-performance outdoor apparel where maximum water resistance is required.

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PET Polyester Waterproofing Technologies

Water Repellent Finishes

Water repellent finishes, such as Durable Water Repellency (DWR) treatments, are commonly used to enhance the water resistance of PET polyester fabrics. These finishes modify the fabric surface, reducing its surface tension and allowing water to bead up and roll off. Water repellent finishes can be applied during the finishing process or as a post-treatment to ensure the fabric maintains its water repellency over time.

Polyurethane Coating

Polyurethane coatings are often used to add a waterproof layer to PET polyester fabrics. These coatings can be applied in various thicknesses, depending on the desired level of water resistance. Polyurethane coatings are lightweight, flexible, and breathable, allowing moisture vapor to escape while preventing water from entering the fabric.

Laminated Polyesters

Laminated PET polyester fabrics consist of multiple layers bonded together, with a waterproof membrane sandwiched in between. This construction enhances the fabric’s overall waterproofness, making it highly resistant to water penetration. Laminated polyesters are commonly used in rainwear, outdoor gear, and other applications that require maximum water resistance.

Membrane Technology

Membrane technology involves incorporating a thin, breathable, and waterproof layer into the fabric structure. These membranes are typically made from materials such as polyurethane or ePTFE (expanded polytetrafluoroethylene). They allow moisture vapor to escape while preventing water from entering the fabric. Membrane technology is commonly used in high-performance outdoor apparel, where breathability and water resistance are both essential.

Uses and Applications

Outdoor Apparel

PET polyester fabrics with water resistance properties are commonly used in outdoor apparel, such as jackets, pants, and base layers. These fabrics help to keep the wearer dry and comfortable, even in wet and challenging conditions. Outdoor enthusiasts, hikers, and mountaineers often rely on PET polyester garments for their water repellency and durability.

Sleeping Bags and Tents

PET polyester fabrics are also widely used in the production of sleeping bags and tents. The water resistance of these fabrics helps to keep the interior dry, providing a comfortable and protected sleeping environment. PET polyester sleeping bags and tents are popular choices for camping, hiking, and other outdoor activities.

Upholstery and Home Furnishing

PET polyester fabrics with water resistance properties are commonly used in upholstery and home furnishing applications. These fabrics can withstand spills and moisture, making them suitable for furniture, cushions, and curtains in areas prone to moisture or high traffic. The water repellency of PET polyester fabrics in home furnishings helps to maintain their appearance and prolong their lifespan.


One of the primary applications of PET polyester fabrics is in the production of rainwear, such as raincoats and rain pants. The water resistance of PET polyester ensures that the wearer remains dry even in heavy rainfall. These garments are designed to repel water and prevent it from soaking into the fabric, providing protection and comfort in wet weather conditions.


PET polyester fabrics are commonly used in sportswear, including athletic tops, bottoms, and outerwear. The water resistance of these fabrics is particularly beneficial for activities such as running, hiking, and cycling, where moisture management is essential. PET polyester sportswear helps to keep the wearer dry and comfortable, enhancing their performance and overall experience.

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Outdoor Gear

PET polyester fabrics with water resistance properties are also utilized in various outdoor gear, such as backpacks, duffel bags, and tents. The water repellency of these fabrics helps to protect the gear inside from moisture and water damage. PET polyester outdoor gear is designed to withstand the elements and provide reliable performance in outdoor adventures.

Care and Maintenance


To maintain the water resistance of PET polyester fabrics, it is important to follow proper cleaning procedures. Most PET polyester garments can be machine washed in cold or warm water with a mild detergent. It is recommended to avoid using fabric softeners, bleach, or harsh chemicals, as they can negatively impact the fabric’s water repellency. After washing, PET polyester garments should be air-dried to maintain their shape and water repellency.


Over time, the water resistance of PET polyester fabrics may diminish due to wear, washing, or exposure to environmental factors. To restore the water repellency, reproofing treatments can be applied to the fabric surface. These treatments are available in the form of sprays, wash-in solutions, or aerosols. It is important to follow the manufacturer’s instructions when applying reproofing treatments to ensure optimal results.

Special Instructions

Some PET polyester fabrics may have specific care instructions due to additional treatments, coatings, or laminations. It is important to carefully read and follow the care instructions provided by the manufacturer to maintain the fabric’s water resistance and overall performance. Ignoring or neglecting these instructions can lead to the deterioration of the fabric’s water repellency and other properties.

PET Polyester vs. Other Waterproof Fabrics


Nylon is another popular fabric used for waterproof applications. While both PET polyester and nylon offer water resistance, there are some differences between the two. Nylon tends to be lighter in weight and more breathable than PET polyester. However, PET polyester is known for its superior durability and resistance to abrasion. Additionally, PET polyester fabrics are often more cost-effective compared to nylon.


Polypropylene is another synthetic fabric that can exhibit water resistance properties. However, polypropylene is generally not as durable or strong as PET polyester. Polypropylene fabrics are often used in applications where lightweight and moisture management are the main priorities.

Polyurethane Film

Polyurethane film is a waterproof material that is commonly used as a coating on fabrics. This film provides a barrier against water penetration, making it highly effective in waterproofing applications. While PET polyester can be coated with polyurethane to enhance its water resistance, the use of polyurethane film as a standalone material is often limited to specific applications where maximum waterproofness is required.


Gore-Tex is a popular brand of waterproof and breathable membranes used in outdoor apparel and gear. While PET polyester fabrics can be laminated with a Gore-Tex membrane to achieve exceptional water resistance and breathability, Gore-Tex fabrics are often more expensive. PET polyester offers a more cost-effective option for those seeking water resistance without the premium price tag.


In conclusion, PET polyester is a highly versatile fabric that offers excellent water resistance properties. Its inherent hydrophobic nature, combined with various waterproofing technologies, makes it a popular choice in numerous applications. PET polyester fabrics with water resistance properties are commonly used in outdoor apparel, sleeping bags, tents, upholstery, rainwear, sportswear, and outdoor gear. With proper care and maintenance, PET polyester fabrics can maintain their water repellency for an extended period, ensuring comfort, protection, and reliability for the wearer.