DWR refresh: Spray vs. wash-in for rain shell?

Understanding DWR and Its Importance

Your trusty rain shell is your first line of defense against the elements, and a key component of its performance is the Durable Water Repellent (DWR) finish. This invisible coating causes water to bead up and roll off the fabric, preventing it from saturating the outer layer and allowing the garment’s breathable membrane (like Gore-Tex or eVent) to do its job effectively. Over time, dirt, oils, abrasion, and repeated washing degrade the DWR, causing the fabric to ‘wet out’ – meaning it absorbs water, feels heavy, and significantly reduces breathability.

When your rain shell starts to absorb water instead of repelling it, it’s a clear sign that its DWR needs a refresh. But faced with a shelf full of options, a common dilemma arises: should you choose a spray-on or a wash-in treatment? Both methods aim to restore water repellency, but they achieve it in different ways and are better suited for specific scenarios.

Wash-In DWR Treatments: Pros and Cons

Wash-in DWR treatments are applied during a regular wash cycle in your washing machine. The DWR chemicals are dispersed throughout the water and bond to the fabric fibers during the wash, effectively coating both the outer and inner surfaces of the garment.

Pros:

• Even Coverage: This method ensures that the entire garment, including seams and less accessible areas, receives a uniform application of DWR.
• Ease of Use: It’s a straightforward process, much like washing clothes, requiring minimal effort once the garment is in the machine.
• Internal Repellency: For non-lined garments or those with mesh linings, wash-in treatments can also provide some water repellency to the internal fabric, which can be beneficial.

Cons:

• Potential Breathability Impact: The biggest drawback is that wash-in treatments can coat all fabric surfaces, including the inside of the garment and any wicking liners. This can potentially reduce the breathability of the fabric, as it interferes with the membrane’s ability to transfer moisture vapor away from the body. This is particularly noticeable on garments with breathable linings.
• Less Targeted: If only specific areas (like shoulders or elbows) are wetting out, a wash-in treatment might be overkill and less efficient.

Spray-On DWR Treatments: Precision and Performance

Spray-on DWR treatments are applied directly to the outer surface of the clean, wet, or dry garment. This method allows for targeted application and often comes in a pump or aerosol bottle.

Pros:

• Maintains Breathability: By only treating the outer fabric, spray-on DWR preserves the breathability of the inner lining and the membrane, ensuring your jacket continues to vent sweat effectively. This is crucial for high-performance shells.
• Targeted Application: You can focus the treatment on areas that experience the most wear and tear, such as shoulders, cuffs, and the front of the jacket, without treating areas that don’t need it.
• Versatility: Suitable for garments with various types of linings, especially those designed to wick moisture away from the skin.

Cons:

• Uneven Coverage Risk: Achieving perfectly even coverage can be challenging, leading to missed spots if not applied carefully.
• More Labor Intensive: Requires more hands-on effort and attention during application compared to simply adding a product to a wash cycle.
• Potential for Streaks: If not applied and spread properly, spray-on treatments can sometimes leave visible streaks or residue.

Choosing the Right Method for Your Rain Shell

The best method largely depends on the type of rain shell you have and its current condition:

• For High-Performance, Breathable Shells (e.g., Gore-Tex Pro, eVent): A spray-on DWR is generally recommended. This preserves the internal lining’s wicking properties and ensures the membrane’s breathability is not compromised.
• For Basic Rain Jackets or Those with Non-Wicking Linings: A wash-in DWR can be a good, convenient option. If the inner fabric isn’t designed for specific wicking performance, the internal DWR coating won’t significantly hinder its function.
• When Only Specific Areas Wet Out: If your jacket generally performs well but has a few worn spots (e.g., under backpack straps), a spray-on treatment allows you to target these areas efficiently without re-treating the entire garment.
• For Uniform Wet Out Across the Entire Garment: If the entire jacket is absorbing water uniformly, a wash-in treatment can ensure thorough and even restoration across all surfaces. However, consider the breathability implications if it’s a high-performance shell.

Application Best Practices and Maintenance Tips

Regardless of the method you choose, proper preparation and application are key to maximizing the DWR’s effectiveness:

1. Clean First: Always clean your rain shell thoroughly before applying DWR. Use a technical wash designed for outdoor gear, as regular detergents can leave residues that inhibit DWR bonding. Follow the garment’s care instructions.
2. Check Instructions: Read the instructions on your chosen DWR product carefully, as application steps can vary slightly between brands and formulas.
3. Activate (Often): Many DWR treatments require heat activation to properly bond to the fabric. This usually involves tumble drying on a low heat setting or ironing on a low, synthetic setting (check garment labels).
4. Regular Care: A DWR refresh isn’t a one-time fix. Regular cleaning and occasional reapplication (every few months or after heavy use) will extend the life and performance of your rain shell. Sometimes, a simple wash and low-heat tumble dry can reactivate an existing, diminished DWR.

Conclusion

Both spray-on and wash-in DWR treatments are effective tools for restoring your rain shell’s water repellency. The choice ultimately boils down to balancing convenience, your garment’s specific design, and your priorities regarding breathability. For high-performance, breathable shells, spray-on is often the superior choice to maintain optimal function. For simpler jackets or when uniform coverage is paramount, a wash-in treatment can be an excellent, easy solution. By understanding these differences and following proper application techniques, you can ensure your rain shell continues to protect you, trip after trip, no matter the weather.