Dirt and sweat impair the breathability of functional materials.
Waterproof and water-repellent are two different things. A membrane or a PU-coating care about the waterproofness, a durable-water-repellent (DWR) impregnation cares for the water-repelling. The DWR prevents the garment of being soaked with rain. Without DWR the pressure of the moisture from the outside would become so high, that water vapor from the inside can not escape any more. The garment loses its breathability, the water vapor cools down and condensates on the inside of the garment. The jacket feels wet and you begin to cold. Thus you mistakenly think that the jacket is „not waterproof any more“ – thereby it is solely endogenous sweat that deposits on the inside of the jacket.
Over time DWR-outfits lose their funktion (e.g. through the straps of a backpack or abrasion through movement). Threating them with warmth (room-temperature is emough) after washing can re-activate them. Regular washing and impregnating restores the function of outdoor-gear lastingly and extends their durability.
Regular washing with a gentle cleanser restores the natural water-repellent features and the breathability of the garment. Please do not use any normal cleansers. These are enriched with tensides that leave debris in the spaces of the membrane and thus reduce the breathability. Also they are hydrophilic and hence the death of any imprenation agent.
The cleanser should be appropriate for the cleaning of „membrane“-clothing and spare chlorofluorocarbons that harm health and environment. At the end of the wash cycle another rinse is advisable, because this removes the last tensides. Even more gentle is washing by hand (inside and outside). Please wash the garment as written in the care instructions. After washing the clothing should drip-dry until it is only moist.
Correct washing prepares the garment ideally for the re-impregnation, which can only work optimum if all dirt and body fat were removed.
Depending on material and use of the garment, the impregnation „bristles“ have gotten so light after several washing cycles, that a re-activation is not possible any more. If waterdrops do not drip off any more it needs a re-impregnation. Imprenation agents are available as wash-in- or spray-on- products. Most of them evolve their function through warming, but room-temperature is enough.
Wash-in-impregnation agents can also be used without washing cycle. In general their benefit is that they apply consistently on the garment. Their disadvantage is that they also apply on the inside of the garment and can impair the breathability.
Spraying on impregnation agents has the benefit, that more stressed parts can be pinpoint and impregnated more intensively. Ideally spray on the still moist, freshly washed clothing so that the agent can permeate deeply into the fibre.