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As users of backpacks in various aspects of our lives, we understand the importance of keeping belongings dry and protected. A water-repellent backpack is essential whether it’s a sudden downpour on the way to school, a splash during a commute, or unexpected weather during travel.
While some backpacks offer built-in water resistance, the key to long-term protection, regardless of the backpack’s purpose, is a Durable Water Repellent (DWR) coating. This invisible shield causes water to bead up and roll off the fabric, preventing it from soaking through.
But with numerous DWR options available, the question becomes: what is the best DWR coating for backpacks? This comprehensive guide will delve into the world of DWR, explaining its function, the factors to consider when choosing one, and how to maintain it properly, ensuring your belongings stay safe and dry.
Understanding Durable Water Repellent (DWR) Coatings
At its core, a DWR coating is a chemical treatment applied to the fabric of a backpack (or any outdoor gear) that creates a hydrophobic surface. This doesn’t make the fabric inherently waterproof; it reduces its surface tension. Water droplets must maintain their rounded shape and roll off instead of spreading out and soaking in.
DWR often works with a waterproof membrane, especially in higher-end backpacks for outdoor activities or travel. This membrane is the main barrier, preventing water from penetrating the pack. However, if the outer fabric becomes saturated (“wetting out”), the membrane’s breathability is compromised, potentially leading to a clammy feeling and condensation buildup. DWR’s primary role is to prevent this from wetting out and ensure the membrane’s effectiveness and overall comfort.
It’s important to remember that the longevity and effectiveness of the DWR finish are affected by factors like abrasion, dirt, and even everyday oils from our hands. Over time, these elements degrade the coating, reducing its water-repelling capabilities.
Different Types of DWR Coatings
Historically, many DWR coatings contained perfluorinated chemicals (PFCs), specifically long-chain PFCs like PFOA and PFOS. These chemicals proved incredibly effective at repelling water and oil. However, they are also persistent environmental pollutants linked to various health concerns. Consequently, the industry is actively transitioning away from these long-chain PFCs.
Currently, most manufacturers utilize shorter-chain PFCs (C6 DWR) or completely PFC-free alternatives. While C6 DWRs are considered less harmful than their long-chain predecessors, they still present environmental concerns.
PFC-free DWRs, often based on silicone or hydrocarbon formulations, are gaining popularity as a more environmentally responsible choice. However, their long-term durability compared to older PFC options is still an area of ongoing development. When selecting the best waterproof backpack spray, carefully consider the chemical composition.
Choosing the Best DWR Coating for Your Backpack
When selecting a DWR coating for backpacks, consider these key factors:
Environmental Impact
Prioritize PFC-free or C6 DWRs to minimize your environmental footprint. Look for products with certifications such as bluesign® or Oeko-Tex®, which signify adherence to stringent environmental and safety standards.
Furthermore, investigate the manufacturer’s overall sustainability practices. Some companies are transparent about their manufacturing processes, water usage, and efforts to reduce waste, providing a more holistic view of their environmental commitment.
Durability
Consider how long the coating is expected to last before requiring reapplication. Some DWR treatments are formulated for more frequent use and need more regular application, while others are designed for longer-lasting protection. Carefully review product reviews and manufacturer specifications.
Consider the type of abrasion your backpack typically experiences. If you frequently scrape your pack against rocks or rough surfaces, a more abrasion-resistant DWR, even if it requires slightly more frequent reapplication, might be a better choice than a super-long-lasting but less robust option.
Application Method
DWR coatings are available in various forms, primarily spray-on and wash-in:
- Spray-on: These are convenient for treating specific areas or quick touch-ups. They allow targeted application but might not provide uniform coverage as wash-in options.
- Wash-in: These require washing the entire backpack, guaranteeing even coverage. They are generally more effective for restoring overall water repellency but may impact the breathability of the backpack if not rinsed thoroughly.
Compatibility
Ensure the DWR treatment is compatible with your backpack’s fabric. Most treatments suit nylon and polyester, but some may not be ideal for certain coated fabrics. Always consult the manufacturer’s instructions. Consider the fabric water repellent properties of your backpack’s material.
If your backpack has multiple fabric types, consider testing the DWR on a small, inconspicuous area first to ensure it doesn’t cause discoloration or damage before treating the entire bag.
Intended Use
While all DWR coatings aim to repel water, some are better suited for specific activities. A heavy-duty DWR might be overkill for a school backpack water repellent, while a travel backpack might require a more robust solution.
Consider also the climate in which you’ll be using the backpack. A less intense DWR might suffice if you live in an area with frequent, light rain. However, a more water-resistant and durable option is crucial if you face heavy downpours or snow.
Breathability
If you have a backpack that needs to be breathable, find a DWR that won’t negatively affect it. Some DWR treatments, especially older formulations or improperly applied wash-in treatments, can clog the fabric’s pores, reducing its ability to allow moisture vapor to escape, leading to discomfort.
Look for DWR products that specifically mention maintaining or enhancing breathability. These formulations are often designed with smaller molecules less likely to clog the fabric’s pores.
DWR: Relevance and Criteria Across Backpack Types
This table outlines the relevance and key criteria for Durable Water Repellent (DWR) finishes across various backpack types, from everyday use to specialized activities. Understanding these factors helps determine the appropriate water protection and durability level needed for each specific application.
| Backpack type | Explanation |
| School backpacks | Relevance: High. DWR protects contents like books and electronics from rain and spills. Key criteria include good water repellency for light precipitation, high abrasion resistance to withstand daily wear and tear, a non-toxic formulation for safety, ease of cleaning and maintenance, and affordability. |
| Work backpacks | Relevance: Moderate to High. DWR helps protect electronics and documents from unexpected weather during commutes. Important factors are reliable water repellency for moderate rain, a professional aesthetic that complements business attire, durability to withstand daily use and occasional travel, and simple maintenance. |
| Commuter backpacks | Relevance: High. DWR is essential for shielding contents from unpredictable weather during commutes, including heavy rain and splashes. Prioritized criteria are high water repellency, durability to withstand frequent use and exposure to the elements, and breathability to manage moisture during active commutes. Reflective elements are a valuable addition for safety. |
| Travel backpacks | Relevance: High. DWR protects belongings from diverse weather conditions encountered during travel. Key considerations include high water repellency for prolonged exposure to rain and snow, robust durability and abrasion resistance to handle rough handling, long-lasting performance to maintain effectiveness over multiple trips, and a lightweight design. |
| Hiking backpacks | Relevance: Very High. DWR is critical for safeguarding gear in challenging outdoor environments. Essential criteria are exceptional water repellency to handle heavy rain, snow, and stream crossings, superior durability and abrasion resistance against rough terrain, long-lasting performance in harsh conditions, and breathability to prevent internal condensation. |
| Everyday carry (EDC) backpacks | Relevance: Moderate to High. DWR provides valuable protection for everyday essentials against varying weather conditions. The focus is on a balance of water repellency, durability for daily use, maintaining the backpack’s style without compromise from the DWR treatment, and easy care and maintenance. |
| Sports backpacks | Relevance: Moderate to High (sport-dependent). Depending on the sport, DWR protects gear from sweat, rain, or water splashes. The main requirements include good water repellency, fast-drying capabilities, abrasion resistance to withstand activity-related wear, breathability to manage moisture, and a lightweight construction. |
Applying and Maintaining DWR on Your Backpack
Re-waterproofing a backpack is an important part of backpack care, extending its lifespan and functionality. Here’s a step-by-step guide:
- Cleaning: Before applying any DWR treatment, thoroughly clean your backpack. Dirt, oil, and other residues can prevent the DWR from properly bonding with the fabric. Use a mild detergent designed for technical fabrics or general use, and follow the manufacturer’s washing instructions. Avoid fabric softeners or bleach, as these can damage the fabric and the DWR coating.
- Application:
- Spray-on: Hang the backpack in a well-ventilated area. Apply the spray evenly, holding the can approximately 6-8 inches away. Overlap each spray pass slightly to ensure complete coverage. Allow it to dry completely according to the product’s instructions.
- Wash-in: Follow the product instructions meticulously. Typically, you’ll add the DWR treatment to the washing machine during the rinse cycle. Use the correct amount of treatment for the backpack’s size.
- Drying: Some DWR treatments require heat activation to fully bond with the fabric. Check the product instructions. You might need to tumble dry the backpack on low heat or use a hairdryer to activate the DWR.
- Maintenance: Regularly clean your backpack to prevent the buildup of dirt and oils. Reapply DWR as needed, typically after several washes or when the fabric begins to absorb water rather than repel it.
Signs Your Backpack Needs a DWR Refresh
Several telltale signs indicate that your backpack’s DWR coating is deteriorating. Water no longer beads up and rolls off the surface but soaks into the fabric. The backpack feels noticeably heavier when wet, and the fabric takes longer to dry.
You might also experience reduced breathability, leading to a damp feeling inside the pack. If you observe any of these signs, it’s time to reapply a DWR treatment to restore backpack water resistance.
Conclusion
A well-maintained DWR coating is essential for keeping any backpack – whether for school, work, travel, or outdoor adventures – and its contents dry and protected. By understanding the different types of DWR available, choosing the appropriate product, and applying it correctly, we can significantly extend the life of our backpacks and ensure their functionality in various conditions.
While the quest for the perfect balance between performance, durability, and environmental responsibility continues, prioritizing PFC-free options and regular maintenance will help us minimize our impact while maximizing the usefulness of our backpacks.