Understanding the Waterproof Rating

Understanding what a waterproof rating means, what the difference between water-resistance and waterproof is and the methods and materials used to achieve protection against water.

Waterproof ratings, or Ingress Protection ratings (IP), are standardized measures that indicate the level of protection an item has against solids (like dust) and liquids (like water). Smartphones have them and waterproof jackets and bags as well.

The rating typically follows the format “IP” followed by two digits or a digit and an “X” (e.g., IPX7). The first digit represents protection against solids, while the second digit represents protection against liquids.

For waterproof backpacks, the focus is primarily on the second digit. Waterproof clothing on the other hand needs to find a balance between waterproof and breathability.

Common Waterproof Ratings

1. IPX6: Protection Against Powerful Water Jets

• Explanation: An IPX6 rating means the backpack can withstand powerful water jets from any direction. It’s great for heavy rain or splashing but not for submersion.
• Example: The Breakwater Supply Fogland Waterproof Backpack and FE Active Cloudbreak 30L are rated IPX6, making them ideal for activities like kayaking or hiking in heavy rain.

2. IPX7: Protection Against Immersion Up to 1 Meter

• Explanation: Backpacks with an IPX7 rating can be submerged in water up to 1 meter (3.3 feet) deep for up to 30 minutes. This rating is suitable for short periods of accidental submersion, such as dropping the bag in a stream.
• Example: The Patagonia Guidewater, Yeti Panga 28L, and Isle Gateway all have IPX7 ratings, ensuring your gear stays dry even if you encounter unexpected water exposure.

3. IPX8: Protection Against Continuous Submersion Beyond 1 Meter

• Explanation: An IPX8 rating indicates that the backpack can handle continuous submersion in water deeper than 1 meter. The manufacturer specifies the exact depth and duration. This is the highest standard for waterproofing.
• Example: The Sea to Summit Big River Backpack and Vitchelo Waterproof Backpack are rated IPX8, making them suitable for prolonged water activities like diving or extended kayaking trips.

Waterproof Fabric Ratings

• 5,000mm – 10,000mm: Suitable for light to moderate rain and brief exposure.
• 10,000mm – 15,000mm: Suitable for heavy rain and snow, but may soak through under pressure.
• 20,000mm and above: Suitable for extreme weather conditions and prolonged exposure to water.

Tents and waterproof jackets will have the waterproofing of their fabric measured using these numbers.

Waterproof Fabric Guide: Membranes vs. Coatings & Seam Sealing

Waterproof breathability is essential for outdoor gear. Let’s break down the key factors:

• Membranes (ePTFE, Polyurethane, Polyester): Often found in high-end gear like GORE-TEX, these offer great breathability and durability. 2L and 3L fabrics are ideal for snow sports, while lighter 2.5L options are suitable for rain protection.
• Coatings: More affordable and waterproof, but less breathable than membranes. Best for casual use or emergency weather protection. DWR (Durable Water Repellent) is the most common of these in waterproof jackets and water-resistant bags, for example. PU (Polyurethane) coating of Nylon is also pretty inexpensive and widely used..
• Seam Sealing: Crucial for preventing leaks, especially in high-exposure areas.

Membranes and coatings have a negative environmental impact because of they often contain PFCs (perfluorocarbons) and run-off that spreads when the materials are washed.

New DWR Methods

Recognizing the need for environmental protection, Patagonia is actively transitioning to PFC-free DWR finishes for all its products by 2025. They promise that their coatings are bio-degradable.

You can find other eco-minded products from brands like Nikwax, Granger’s, and ReviveX.

Maintaining DWR:

Regular washing and tumble drying on low heat to reactivate the DWR coating and maintain its effectiveness is suggested by most companies.

If water stops beading on the fabric, it’s time to reapply a DWR treatment.

Nylon: A Common Waterproof Material

Nylon itself is not inherently waterproof. However, it can be treated or coated to become water-resistant or waterproof. Nylon is widely used for bags and clothing, including some waterproof items, due to its:

• Durability: It is strong and abrasion-resistant.
• Lightweight: Makes it comfortable to wear and carry.
• Versatile: Can be woven into different textures and weights.

Waterproofing Nylon:

To make nylon waterproof, several methods are used:

• PU Coating: A thin layer of polyurethane is applied to the fabric’s surface, creating a barrier against water.
• Silicone Coating: Similar to PU, but silicone provides a softer, more flexible finish.
• DWR: This coating is applied to the fabric’s surface to make water bead up and roll off.
• Laminates: A waterproof membrane is bonded to the nylon fabric for higher performance waterproofing.

RF Sealing

1. Process: High-frequency radio waves are passed through two or more layers of thermoplastic material placed between electrodes.
2. Heating: The radio waves cause the thermoplastic molecules to vibrate, generating heat and melting the material.
3. Bonding: The melted material fuses together under pressure, creating a strong and waterproof seal.

RF sealing is commonly used for:

• Medical products: IV bags, blood bags, surgical drapes
• Industrial products: Inflatable structures, water tanks, protective clothing
• Consumer products: Waterproof bags, rainwear, tents

Advantages of RF sealing:

• Strong and durable seals: The seals created are often stronger than the surrounding material.
• Fast and efficient: The process is quick and can be automated for high-volume production.
• Clean and precise: It leaves no residue or adhesives, making it ideal for aesthetically pleasing products
• Versatile: It can be used with various thermoplastic materials and thicknesses.

Disadvantages of RF sealing:

• Limited to thermoplastics: It only works with specific materials that can melt and re-solidify.
• Equipment cost: RF sealing machines can be expensive.
• Expertise required: Proper operation and maintenance of the equipment require specialized knowledge.

Overall, RF sealing is a highly effective method for creating waterproof seams in specific applications.

Choosing the Right Waterproof Gear

When selecting a waterproof backpack or waterproof jacket, consider the activities you plan to undertake. For occasional exposure to rain or splashes, an IPX6-rated backpack may suffice. However, for more intense water activities, an IPX7 or IPX8 backpack provides better protection for your belongings.

Just because an item is described and sold as “waterproof” doesn’t guarantee that water won’t get in. For our reviews, we’ve proven this during testing of products that claim water protection, but end up failing anyway.

To ensure your gear stays dry in various outdoor activities or during a rainy commute, choosing the right backpack, jacket or pants with an appropriate waterproof rating is crucial. There are backpacks designed with different levels of protection to meet the specific needs of activities like hiking, kayaking, or city commuting.

To make an informed choice, always check the specific waterproof rating of the backpack and select the one that aligns with your intended use, ensuring optimal protection and dryness for your belongings.