Is Polyester Waterproof?

by Editorial Staff | Updated on October 1st, 2023

Polyester is renowned for its waterproof characteristics, but the degree of waterproofing depends on several factors. At its core, polyester is a synthetic fiber, inherently possessing a significant level of water resistance due to its tight weaving and density. When we increase the density and the number of threads in the weaving process, the material’s ability to resist water improves markedly.

However, even a fabric made from 100% polyester cannot claim absolute waterproofing. To enhance its waterproof characteristics, polyester often undergoes specific treatments or is combined with other water-repelling materials. Coatings or layers of water repellents, such as rubber or a laminate layer, are applied to the fabric. This additional treatment or coating not only enhances its resistance to water but also fortifies the fabric against various weather elements while maintaining its breathability to a certain extent.

For individuals engaged in outdoor activities, understanding the nuances of waterproof gear is crucial. The market is replete with products claiming to be waterproof, and many of these are made from polyester. Often, consumers trust these claims and invest in polyester-based outdoor apparel expecting complete protection from rain and moisture. It is essential to understand that while polyester offers substantial protection, its effectiveness is contingent on the treatment it has undergone and its density and thread count.

Is Polyester Water-Resistant?

Water resistance in polyester is indeed inherent, but it’s not absolute. The fabric’s thickness and the number of threads used play a pivotal role in determining its level of water resistance. For instance, a tent made from thick polyester can effectively keep rain out, providing a dry interior. Conversely, thin polyester garments, like leggings, might succumb to moisture quickly.

Noteworthy is polyester’s quick-drying characteristic. When it does get wet, it doesn’t retain moisture for long, drying much faster than many other fabrics. This makes it a practical choice for wear in environments where it might get wet, but complete waterproofing isn’t crucial.

Understanding “Daily Waterproof” Polyester

Polyester has garnered a reputation for being “daily waterproof” due to its commendable water resistance. The term refers to the fabric’s ability to handle everyday situations where water resistance is needed, like light rain or snow. Apparel like windbreakers, raincoats, and winter jackets often employ polyester as a primary material for this reason.

Major retailers and brands, including Lands’ End and North Face, offer a range of jackets made from polyester. These products not only offer resistance against moisture but also provide additional benefits. Polyester is celebrated for its durability, windproof nature, stain resistance, and resistance to mildew and tears. Its composition of strong plastic fibers ensures that it can withstand wear and tear, making it a long-lasting material for outdoor gear.

Moreover, maintaining polyester is relatively hassle-free. Its moisture-resistant surface allows for easy cleaning of mud and stains without damaging the fabric’s integrity. However, it’s important to note that polyester has limitations, particularly when exposed to high temperatures. The fabric tends to melt under intense heat, which could be dangerous in certain situations.

Waterproof vs. Water-Resistant Fabrics

Understanding the difference between waterproof and water-resistant fabrics is crucial when selecting materials for specific uses. Waterproof fabric is impermeable to water, meaning it provides a complete barrier against moisture. This characteristic is rarely found in materials in their natural state; most fabrics acquire their waterproof status through the application of special coatings or sealants. However, these treatments often compromise the breathability of the fabric.

In contrast, water-resistant fabrics can repel water to some degree but are not completely impermeable. These materials can handle a certain amount of water but will eventually succumb to saturation under prolonged exposure or heavy pressure. Water-resistant fabrics are often adequate for everyday situations where complete waterproofing is not a necessity.

Decoding Polyester

Polyester, scientifically known as Polyethylene Terephthalate (PET), is a synthetic fiber derived from a chemical reaction involving mono-ethylene glycol (MEG), terephthalic acid (PTA), water, air, and petroleum. Despite the presence of naturally occurring polyester, the synthetic variant dominates the textile and garment industries due to its versatility and durability.

Polyester Varieties

Polyurethane Laminate (PUL)

Polyurethane Laminate (PUL) is a type of polyester variant where a laminate layer is fused onto lightweight polyester fabric. PUL exhibits moderate stretch, and breathable qualities, and is machine washable. Frequently used in creating shower curtains and sports equipment, PUL stands out for being water-resistant and durable while maintaining a degree of softness and flexibility.

Thermoplastic Polyurethane (TPU)

Another variant, Thermoplastic Polyurethane (TPU), is crafted by bonding a polyurethane membrane to polyester fabric. Although TPU shares similarities with PUL, it possesses a softer texture, albeit at the expense of being less durable. Its applications extend to manufacturing survival jackets, drysuits, and protective garments that boast UV protection.

Polyester with PVC Coating

For utmost water resistance and waterproof capabilities, PVC-coated polyester is the premier choice among the polyester variants. In this version, polyester fabric is backed with a coating of polyvinyl chloride (PVC), resulting in a stiff but impeccably waterproof material. Known for its high durability and superior denier, PVC-coated polyester is the go-to material for products like luggage, banners, and upholstery that demand water-proof characteristics.

Polyester in Outdoor Clothing

Given its commendable durability and water-resistant properties, polyester has been widely adopted in the production of outdoor clothing. Its ability to provide insulation without adding unnecessary bulk makes it a favored material among manufacturers of coats and tents. By incorporating additional substances into the polyester blend, its water-resistant qualities can be further enhanced, resulting in a material that is seemingly waterproof at first glance.

In the context of tents, the application of sealants or waterproofing agents on the exterior helps prevent water penetration, providing a dry and comfortable shelter. This feature is particularly useful for tents, as they don’t require frequent washing, thus prolonging the life of the sealant coating.

Waterproof Fabrics

When perusing the outdoor clothing section, one can observe a plethora of garments labeled as either water-resistant, waterproof or even water-repellent. However, understanding the distinctions among these classifications can be perplexing.

Water-Repellent Fabrics

Water-repellent fabrics provide minimal protection against moisture. These are suitable for light rains but may not hold up well under heavy downpours.

Water-Resistant Fabrics

Fabrics like nylon, wool, and polyester fall under this category. They offer substantial resistance to water but aren’t completely waterproof. These are apt for handling severe rain but aren’t designed for submersion in water.

Waterproof Fabrics

Materials like PVC-coated polyester, vinyl, ripstop nylon, PUL, nylon taffeta, oilcloth, and laminated cotton offer complete water protection. These are suitable for extreme conditions involving severe rain, water submersion, and snow, providing comprehensive protection against moisture.

Polyester Shrinkage

While polyester does exhibit shrinkage, it is not due to exposure to water but rather to heat. Washing polyester in hot water or drying it in a hot dryer can cause the material to shrink. However, there are methods available to intentionally shrink polyester without damaging the fabric, providing options for individuals looking to resize their polyester garments. Notably, polyester is resistant to fading, retaining its color for an extended period.

Polyester as water-repellent

While polyester can act as an effective water-repellent, its efficiency is determined by the thickness of the fabric and the density of the threads. Thick polyester, akin to the material used for tents, can effectively repel water, keeping the interior dry. However, thinner variants of polyester may get wet quickly but also dry rapidly.

What Happens When Polyester Gets Wet?

Despite polyester fibers being inherently waterproof due to their plastic composition, the weaving process introduces gaps that can allow water to seep through, making the garment wet. If polyester remains wet for an extended period, it may develop an unpleasant odor. However, its quick-drying property minimizes this risk.

Polyester Jacket Limitations

While a polyester jacket can provide waterproof protection for a limited duration under varying conditions, it is not foolproof. The waterproofing in the fibers doesn’t necessarily translate to the entire garment due to the presence of gaps between woven threads. These gaps can permit water entry, making the wearer damp.

Understanding Waterproof Fabrics

When considering polyester and its water-resistant qualities, it’s imperative to understand the distinction between truly waterproof fabrics and those that are merely water-resistant or water-repellent. Waterproof fabrics offer an absolute barrier, preventing any moisture from seeping through. This kind of impermeability is rarely found in raw materials; most fabrics achieve their waterproof status through specialized treatments, coatings, or the application of waterproof layers or membranes.

Fabrics Suitable for the Rainy Season

For a material to be considered apt for heavy rain, it must be able to repel water effectively, preventing any moisture from penetrating through the fabric. Various fabrics meet these criteria, including:

• TPU and PUL: Both offer waterproof qualities with subtle differences in texture and durability.
• PVC-Coated Polyester and Rubber-Coated Polyester: These provide a rigid but extremely waterproof material.
• Vinyl, Nylon Taffeta, and Oilcloth: All three are recognized for their waterproof properties and are effective in heavy rain situations.

Polyester’s Durability

Polyester boasts significant durability, primarily due to its plastic composition. Depending on its weave and thickness, it can handle varying weights, making it a versatile choice for different uses. Although inherently water-resistant, polyester can be rendered more waterproof through the application of specific coatings, though this tends to increase the cost of the final product due to the complexity of the process.

Does Polyester Absorb Water?

Polyester’s hydrophobic nature means it does not readily absorb water. However, its water absorption capacity depends on its thickness and thread count. When polyester is thin, it can become wet but dries relatively quickly. Manufacturers can increase polyester’s water resistance by augmenting the thread count or applying additional protective layers. However, these modifications only render the fabric water-resistant, not entirely waterproof.

UV Resistance and Flammability

Polyester can absorb UV rays, making it a common choice for UV protection textiles. Nevertheless, for prolonged exposure to sunlight, it’s recommended to use additional UV protection. When it comes to flammability, polyester is not easily ignitable but can melt when exposed to high heat, which can be dangerous.

Nylon vs. Polyester: Waterproof Comparison

Both polyester and nylon are prevalent choices for waterproof garments and accessories. These synthetic materials are appreciated for their durability, resistance to wrinkles and stains, elasticity, and ability to retain their shape. However, polyester has a slight edge over nylon in terms of water repellency. While nylon is softer and stretchier, polyester provides better water resistance. For applications where water repellency is crucial, treated nylon or a blend of nylon and other materials may be used.

Conclusion

In understanding the waterproof capabilities of polyester, it’s vital to acknowledge the variables that influence its effectiveness in repelling water, such as thread count, density, and additional treatments or coatings. While polyester is inherently water-resistant and durable, it is not infallible or entirely waterproof in every form or weave. For those seeking materials for specific uses, like outdoor apparel for heavy rain or garments for water sports, considering the type of polyester, its treatment, and its combination with other materials is crucial for making an informed decision. Always evaluate the specific requirements of the activity and the level of water exposure before selecting polyester-based products to ensure optimal protection and performance.

Editorial Staff

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