What reproofing can and cannot do
The DWR is a surface treatment on the outer fabric. When it wears, the face fabric saturates — 'wets out' — and the jacket feels cold and clammy and loses most of its breathability, even though the membrane underneath still blocks liquid water. Reproofing renews that surface finish. It is the correct fix for wet-out, and for nothing else.
The boundaries matter. A reproofing treatment does not repair a damaged membrane, rebond lifting seam tape, or fix delamination — Patagonia's repair documentation explicitly lists delaminated items as unrepairable, and no treatment maker claims its product restores a failed barrier. If water genuinely passes through the fabric or seams, that is a repair or warranty question, not a reproofing one.
Clean first — then test whether you need to reproof at all
Nikwax and Grangers instruct cleaning before reproofing; Arc’teryx recommends washing, drying with permitted heat and checking beading before adding DWR. These are the named sources for the sequence, not a claim about every manufacturer.
Cleaning can remove contamination that impairs repellency. If beading returns after the instructed cleaning and drying steps, additional treatment may not be needed. Follow garment and treatment instructions.
Wash-in versus spray-on
The two application types do the same job differently. Wash-in treatments run in the machine and coat the entire garment, inside and out. Spray-on treatments are applied to the outer surface — Nikwax describes its spray-on as the option for clothing with wicking liners, since it keeps the treatment off the liner, and Arc'teryx's DWR guide states spray offers superior performance and the ability to target high-wear areas such as shoulders and cuffs.
Patagonia's wording is the most even-handed: wash-in treatments can be easier because they coat the entire item, but spray-on options are as effective provided you cover all areas carefully. No official source we reviewed supports a universal rule that one type is always correct — the garment's construction and the product's own instructions decide.
Heat, and the exceptions
Many factory finishes and some aftercare treatments are reactivated or cured by gentle heat — Gore's instructions specify a 20-minute tumble dry or protected gentle ironing after application, where the garment label permits. But heat rules are product-specific: RevolutionRace states its spray needs no heat activation, and Nikwax's TX.Direct requires none. The garment label and the treatment bottle are the authorities, in that order.
Two documented exceptions override everything else. Persistent-beading garments such as GORE-TEX SHAKEDRY must never receive DWR at all — they have no textile outer layer and do not need it. And waxed cotton garments are a different care system entirely: Patagonia's guide specifies spot-cleaning only, with no washing, tumble drying, ironing or steaming.