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How to waterproof a jacket: a step-by-step guide to reproofing

A person in a waterproof jacket looking out to the horizon
Don’t know how to waterproof a jacket? Our tips have you covered (Image credit: Getty)

The good news is that any jacket with a membrane (such as Gore-Tex) should stay waterproof so long as it’s not torn or ripped. The bad news is that these waterproof jackets still need a bit of regular TLC to maintain their performance – a potentially daunting prospect if you don't know how to waterproof a jacket.

Even with the best waterproof jackets, once the jacket’s first line of defence – the Durable Water Repellent (DWR) coating – is compromised, water no longer beads and rolls off the fabric. Instead, the jacket starts to soak up rain – aka ‘wetting out’ – and its breathability suffers (see breathability ratings explained). This leaves you in danger of getting soaked in sweat from the inside, rather than soaked by rain from the outside, and signals the moment when it’s time to invest in specialist cleaning and reproofing products to restore your jacket’s wet-weather performance.

Learn how to use these products in this straight-talking guide on how to waterproof a jacket.

How to waterproof a jacket: step-by-step instructions

1. When to reproof

This depends heavily on use – how dirty is your jacket and how much abrasion has it suffered from backpack straps and rock faces? To test whether it needs reproofing, pour water onto the shoulders and arms of your jacket. If the water beads on the surface there’s no need to take action: if it soaks in (“wets out”) it’s time for a re-proof.

2. Clean your washing machine

The residue of detergent washing powders is kryptonite to DWR (check out our 'What is DWR?' explainer), so it’s important to clean out the powder drawer of your washing machine, and ideally put the machine through a wash cycle with nothing in it to make sure it’s clean.

People trekking in waterproof jackets

DWR treatments make water bead up on the fabric instead of saturating it (Image credit: Getty)

3. Wash your jacket

Choose a specialist cleaner, such as Nikwax Tech Wash or Grangers Performance Wash, pour the recommended dose into the detergent drawer of your washing machine, and set the temperature according to the jacket’s care instructions. A full cycle at 85°F/30°C is normally about right. Don’t be tempted to stuff your entire outdoor wardrobe into the machine – for optimum performance no more than two jackets should be washed at the same time. Make sure to empty the pockets and zip up all zippers of the jacket before washing.

4. Reproof your jacket

There are two options here to waterproof a jacket. Firstly, use a waterproof spray such as Granger’s Performance Repel Plus or Nikwax TX.Direct Spray-On, and apply to a clean, damp jacket from a distance of about 15-20cm. Wipe away any surplus spray after a few minutes.

Alternatively, use a wash-in waterproofing agent, such as Nikwax TX.Direct Wash-In or Grangers Clothing Repel. Pour the recommended dose of the wash-in cleaner into the detergent drawer of your machine and wash again on a full cycle. After washing, hang up the jacket to dry.

To save time, there are two-in-one wash and reproof products, such as Grangers Wash & Repel Clothing 2 in 1.

5. Boost the DWR

To optimise the DWR finish, tumble dry the jacket (if its care instructions allow), or use a hairdryer to apply modest heat to the surface of the fabric. Using an iron on a very low heat has the same positive effect, but make sure there is a tea towel between the iron and the jacket, and keep the temperature on the lowest setting.

6. Check the seams

As a final step, check that the internal taped seams are still intact and in place. If not, use a glue, such as Stormseal Seam Sealer or Stormsure Flexible Repair, to re-attach the seams. If the seam has perished, you can do a DIY repair with 20mm, iron-on seam seal tape, which is specially made for three-layer laminate fabric jackets.