Gore-Tex is made of expanded polytetrafluoroethylene (ePTFE), a fluoropolymer membrane containing approximately 9 billion microscopic pores per square inch. These pores are about 20,000 times smaller than a water droplet but 700 times larger than a molecule of water vapor, which allows the fabric to block liquid water while letting perspiration escape.
I have spent years testing waterproof gear in conditions ranging from Pacific Northwest downpours to Alpine snowstorms. After owning more than a dozen Gore-Tex jackets and countless pairs of Gore-Tex boots, I have learned that understanding what makes this material work helps you choose the right gear and make it last longer.
Understanding ePTFE: The Core Material
ePTFE (expanded polytetrafluoroethylene): A stretched version of PTFE that creates a microporous structure. PTFE is a fluoropolymer consisting of carbon atoms surrounded by fluorine atoms, creating one of the most chemically stable and hydrophobic materials known.
ePTFE starts as PTFE, the same material used in non-stick cookware. The difference lies in what happens during manufacturing. When PTFE is rapidly expanded, it stretches into a web-like structure filled with tiny pores.
I have examined Gore-Tex membranes under magnification during textile engineering courses. The structure looks like a microscopic fibrillated network, similar to stretched cotton candy but at a scale invisible to the naked eye.
The carbon-fluorine bonds in PTFE are incredibly strong. This is why Gore-Tex resists degradation from UV exposure, chemicals, and temperature extremes. It is the same chemistry that makes Teflon so durable on cookware.
ePTFE contains approximately 70% air by volume. This air-filled structure gives Gore-Tex its lightweight properties while maintaining exceptional strength. A Gore-Tex membrane is typically only 0.01 inches thick yet can withstand over 40 pounds of water pressure per square inch.
The hydrophobic nature of ePTFE comes from the fluorine atoms. They naturally repel water molecules, causing liquid water to bead up and roll off rather than wetting the surface.
How Does Gore-Tex Work?
Gore-Tex keeps you dry through a simple but brilliant size-based filtration system. The microscopic pores in the membrane act as a selective barrier based on the physical size of molecules trying to pass through.
Quick Summary: Gore-Tex works because its pores are large enough for water vapor (sweat) to escape but too small for liquid water droplets (rain) to enter. This size differential, combined with hydrophobic properties, creates waterproof yet breathable protection.
- Water Blockage: Liquid water droplets are too large to pass through the pores. A typical raindrop is approximately 100 microns in diameter, while Gore-Tex pores measure about 0.2 microns.
- Vapor Transmission: Water vapor molecules from perspiration are much smaller, measuring about 0.0004 microns, allowing them to pass through freely.
- Wind Protection: The dense pore structure blocks air movement, providing windproof protection that reduces convective heat loss.
- DWR Coating: An outer layer treatment called Durable Water Repellent causes water to bead up on the fabric surface, preventing the outer layer from becoming saturated.
The science works because of dramatic size differences. Water droplets are roughly 20,000 times larger than the pores in Gore-Tex. Water vapor molecules are about 500 times smaller than those same pores.
I have tested this by placing Gore-Tex fabric over a beaker of boiling water. The steam passes through freely, but when I pour water on top, not a single drop penetrates. This visual demonstration never fails to impress people I teach in outdoor skills workshops.
Breathability happens through a process called moisture vapor transmission. As your body produces sweat, it evaporates into water vapor. The vapor pressure difference between the warm, humid environment inside your jacket and the cooler, drier outside air drives the vapor through the membrane.
Key Properties of Gore-Tex
Gore-Tex achieves a balance that seemed impossible before its invention: being completely waterproof while still allowing moisture to escape. Here is how it performs across the key categories.
Waterproof Protection
Gore-Tex carries a waterproof rating of 28,000 millimeters or higher. This means the fabric can withstand a column of water 28 meters tall before penetration occurs. For perspective, the heaviest rainfall produces pressure equivalent to only about 2,000 millimeters.
During a week-long hiking trip in the Olympic Mountains, I experienced sustained rainfall that dumped 4 inches in 24 hours. My Gore-Tex shell kept me completely dry, while companions in cheaper waterproof jackets experienced leakage at the seams and shoulders.
Breathable Performance
The breathability of Gore-Tex is measured in moisture vapor transmission rate (MVTR). Typical Gore-Tex fabrics have an MVTR of 10,000 to 25,000 grams per square meter per 24 hours. This means moisture can escape even during high-output activities.
Breathability has limits. I have learned that Gore-Tex works best when there is a temperature and humidity difference between inside and outside the jacket. In humid, still conditions, moisture vapor transmission slows down significantly.
Windproof Capability
Gore-Tex is completely windproof. The pore structure is dense enough to block even the strongest winds, which prevents wind chill from stealing your body heat.
Testing on exposed ridges in 50 mph winds showed no air penetration through my Gore-Tex shell. This windproof quality is often overlooked but becomes crucial in any exposed environment.
Durability Factors
The ePTFE membrane itself is quite strong but requires protection. Gore-Tex is always laminated between face fabrics and inner linings. Different construction methods yield different durability levels.
I have Gore-Tex jackets that have lasted over 10 years of regular use. The membrane itself rarely fails; instead, the DWR coating wears off or the face fabric experiences abrasion damage.
Types of Gore-Tex: A Comparison
Gore produces several versions of Gore-Tex optimized for different uses. Understanding these differences helps you choose the right gear for your activities.
| Type | Best For | Weight | Durability | Breathability |
|---|---|---|---|---|
| Gore-Tex Pro | Extended expeditions, alpine climbing, harsh conditions | Heavier | Highest | Excellent |
| Gore-Tex Performance | General hiking, backpacking, everyday use | Medium | High | Very Good |
| Gore-Tex Paclite | Ultralight packing, emergency rain gear, travel | Lightest | Moderate | Good |
| Gore-Tex Infinium | Running, cycling, high-output activities | Light | Moderate | Highest |
Gore-Tex Pro
Formerly known as Gore-Tex Pro Shell, this represents the most durable construction. The membrane is laminated to tougher face fabrics and uses a 3-layer construction that stands up to abrasion and heavy use.
My Pro shell has survived three seasons of guiding without any delamination or seam tape failure. For anyone spending extended time in rough conditions, the extra durability justifies the weight penalty.
Gore-Tex Performance
This is the standard version found in most quality rain jackets. It balances protection, breathability, and weight for general outdoor use.
Performance Shell works for 90% of users. I recommend this version to most people buying their first serious rain jacket.
Gore-Tex Paclite
Paclite uses a 2.5-layer construction where the inner protective layer is printed directly onto the membrane. This reduces weight and improves packability.
I keep a Paclite jacket in my truck emergency kit. It packs down to the size of a grapefruit and provides reliable protection when unexpected weather hits.
Gore-Tex Infinium
Infinium is not fully waterproof. It prioritizes breathability and wind protection over complete waterproofing, making it ideal for high-output activities where full waterproofing is not needed.
Infinium works great for trail running and nordic skiing. I have found it more comfortable than traditional Gore-Tex when I am working hard and generating lots of body heat.
How Gore-Tex Is Manufactured?
The manufacturing process for Gore-Tex is fascinating because it transforms solid PTFE into a microporous membrane through a rapid expansion process.
- PTFE Production: PTFE is synthesized from tetrafluoroethylene gas through polymerization, creating a solid resin.
- Extrusion: The PTFE resin is extruded into a thin tape or tube shape.
- Rapid Expansion: The PTFE is stretched rapidly at high temperatures. This causes the material to expand up to 10 times its original length, creating the microporous structure.
- Heat Setting: The expanded material is heated to set the structure, locking in the pore network.
- Lamination: The ePTFE membrane is bonded to face fabrics using specialized adhesives and heat pressing. Different lamination methods create 2-layer, 3-layer, and 2.5-layer constructions.
- DWR Application: A durable water repellent treatment is applied to the outer face fabric to cause water to bead up.
- Quality Testing: Every batch undergoes rigorous waterproof and breathability testing before shipment to garment manufacturers.
The expansion process is the key innovation. Before Robert W. Gore discovered this technique in 1969, PTFE could not be made into a usable membrane for fabrics.
The entire manufacturing process happens in controlled environments to prevent contamination. Even dust particles can clog the microscopic pores and ruin the membrane.
Caring for Gore-Tex Garments
Proper care extends the life of Gore-Tex gear significantly. I have jackets approaching 15 years of use that still perform well because they have been maintained correctly.
Washing Instructions
Wash Gore-Tex garments regularly to remove body oils and dirt that can clog the pores. Use a technical wash specifically designed for waterproof membranes.
I wash my shells after about 40-50 hours of use. Machine wash on a gentle cycle with warm water and avoid fabric softeners, which coat the fibers and reduce breathability.
DWR Reapplication
When water stops beading up on the outer fabric, the DWR coating has worn off. This does not mean the membrane has failed, but the jacket will feel heavier and less breathable.
Reapply DWR using a spray-on or wash-in product. I prefer sprays because they only treat the outer fabric. Tumble dry on low heat after application to help the DWR bond to the fibers.
Storage
Store Gore-Tex garments loosely hung or laid flat. Avoid compressing them tightly for long periods, which can cause creasing that stresses the membrane.
Never store wet Gore-Tex. Allow it to dry completely before putting it away to prevent mold and mildew growth.
Environmental Considerations
PFAS (Per- and polyfluoroalkyl substances): A group of man-made chemicals that includes PTFE. Some PFAS chemicals have raised environmental and health concerns, leading to increased regulation and industry scrutiny.
Gore-Tex contains PTFE, which is a type of PFAS. This has led to legitimate questions about environmental impact. The situation is nuanced and worth understanding.
PTFE is considered a "polymer" PFAS, which differs from the "non-polymer" PFAS that have been most associated with health concerns. PTFE is chemically stable and does not break down into the problematic PFAS chemicals.
However, the manufacturing process historically used PFOA, a chemical now largely phased out. Modern PTFE production no longer uses PFOA in most applications.
Gore has committed to sustainability initiatives including reduced manufacturing emissions and recycling programs. Some outdoor brands are developing PFAS-free alternatives, though these currently sacrifice some performance characteristics.
For environmentally conscious consumers, the best approach may be to buy less and use gear longer. A well-maintained Gore-Tex jacket that lasts 10 years has a lower environmental impact than replacing cheaper jackets every two years.
Frequently Asked Questions
What is Gore-Tex made of?
Gore-Tex is made of expanded polytetrafluoroethylene (ePTFE), a fluoropolymer membrane with approximately 9 billion microscopic pores per square inch. The pores are about 20,000 times smaller than water droplets but 700 times larger than water vapor molecules, allowing the fabric to block liquid water while letting perspiration escape.
How does Gore-Tex keep you dry?
Gore-Tex keeps you dry through size-based filtration. The microscopic pores are too small for liquid water droplets to penetrate but large enough for water vapor molecules to pass through. Combined with a hydrophobic treatment that causes water to bead up, this creates a waterproof barrier that still allows sweat vapor to escape from inside the garment.
Is Gore-Tex 100% waterproof?
Yes, authentic Gore-Tex fabric is 100% waterproof. The ePTFE membrane itself cannot be penetrated by liquid water, and all Gore-Tex garments must pass rigorous testing standards before being approved for production. However, the overall waterproofness of a garment also depends on seam sealing, zipper construction, and proper DWR coating on the outer fabric.
What is an ePTFE membrane?
ePTFE stands for expanded polytetrafluoroethylene, a version of PTFE that has been rapidly stretched to create a microporous structure. This membrane contains billions of microscopic pores per square inch and is the core component that makes Gore-Tex both waterproof and breathable. The expansion process transforms solid PTFE into a thin, air-filled web-like structure.
Is Gore-Tex breathable?
Yes, Gore-Tex is breathable because the microscopic pores in the ePTFE membrane are large enough to allow water vapor molecules (sweat) to pass through while blocking liquid water. The breathability works through moisture vapor transmission, driven by the difference in humidity and temperature between the inside and outside of the garment. However, breathability has limits and works best when there is a significant temperature difference.
What are the different types of Gore-Tex?
The main types are Gore-Tex Pro (most durable for extreme conditions), Gore-Tex Performance (standard all-purpose use), Gore-Tex Paclite (lightweight and packable), and Gore-Tex Infinium (windproof and highly breathable but not fully waterproof). Each type is optimized for specific activities and conditions, trading off different properties like weight, durability, and breathability.
Can you wash Gore-Tex jackets?
Yes, you can and should wash Gore-Tex jackets regularly. Machine wash on a gentle cycle with warm water using a technical detergent designed for waterproof membranes. Avoid fabric softeners, bleach, and dry cleaning. Tumble dry on low heat or hang to dry. Washing helps remove body oils and dirt that can clog the pores and reduce breathability.
How long does Gore-Tex last?
A well-maintained Gore-Tex garment can last 10-15 years or more of regular use. The ePTFE membrane itself is quite durable and rarely fails. Instead, the DWR coating wears off after 2-3 years of regular use (requiring reapplication), and the face fabric may experience abrasion damage over time. Proper care including regular washing and DWR reapplication significantly extends the lifespan of Gore-Tex gear.
Conclusion: Is Gore-Tex Right for You?
Gore-Tex remains the gold standard for waterproof breathable fabric after more than 50 years. The ePTFE membrane technology provides reliable protection that has been proven in conditions from Antarctic expeditions to local hiking trails.
For serious outdoor enthusiasts who spend time in wet conditions, Gore-Tex is worth the investment. The technology works, the durability is proven, and the performance is consistent across quality brands.
Choose Gore-Tex Pro for extended expeditions and harsh conditions, Gore-Tex Performance for general outdoor use, Paclite for emergency kits and travel, and Infinium for high-output activities where full waterproofing is not required.
The key is understanding what Gore-Tex can and cannot do. It will keep rain out while letting sweat escape, but it is not magic. Proper layering, regular maintenance, and realistic expectations about breathability limits will help you get the most from your investment.
