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Waterproofing Reactivation Calculator

Find out if your jacket's DWR coating needs reactivation or replacement.

ℹ

For reference only. Always follow your garment's care label. Results are estimates based on typical DWR degradation patterns.

How old is the jacket?

When did you last wash the jacket? Enter 0 if recently washed.

When did you last tumble dry or iron to reactivate DWR?

Splash water on the jacket and observe

2yr × 10 days = 20 total days · wear score 30/100

RESULT

30/100

Reactivate

Reactivate DWR with heat

1Wash jacket with specialist cleaner (Nikwax Tech Wash or Grangers)
2Tumble dry on low heat for 20 min, OR iron on low through a cloth
3Test by splashing water — it should bead up and roll off

DWR care quick reference

ScenarioActionProducts
After every washTumble dry low 20 min—
Water not beadingReactivate with heatNikwax, Grangers
Fabric wetting outWash-in DWR treatmentTX.Direct, Grangers
Heavy use, old jacketSpray-on DWRTX.Direct Spray
Delamination visibleReplace jacket—
Also useful: Altitude Sickness Risk → · Backpack Weight Calculator →

Based on Gore-Tex care guidelines · Nikwax & Grangers recommendations

DWR explained

What is DWR and why does it degrade?

DWR (Durable Water Repellency) is a chemical coating bonded to the outer fabric fibres of waterproof jackets. It causes water to bead up and roll off rather than soaking into the weave. Without DWR, the outer fabric wets out — it becomes waterlogged, heavy, and dramatically less breathable.

The membrane vs. the DWR

The membrane (Gore-Tex, eVent, etc.) is what actually keeps water from penetrating. DWR is a separate coating on the outer fabric. When DWR fails, rain still can't penetrate, but the wet outer fabric blocks moisture vapour from escaping — you feel clammy even though you're not wet through.

Why heat reactivates DWR

DWR polymers are thermoplastic — heat causes them to stand upright and bond more effectively to fabric fibres. Body oils, detergent residue, and dirt flatten and contaminate the DWR. Washing removes contamination; heat restores the polymer structure.

When DWR can't be restored

  • After many wash cycles, the chemical bond to fabric fibres weakens permanently
  • Heavy abrasion (backpack straps, shoulder areas) physically removes DWR
  • Above ~5–8 years with regular use, re-treatment rarely restores full performance
  • Delamination (bubbling/peeling inner layer) means the membrane itself is failing

This calculator gives estimates. Always do the splash test: pour water on the jacket. Good DWR = water beads and rolls in 1–2 seconds. Failing DWR = water spreads and soaks in.

Frequently asked questions

What is DWR and why does it matter?

DWR (Durable Water Repellency) is a coating applied to the outer fabric of waterproof jackets. It causes water to bead up and roll off. When it fails, the fabric wets out — absorbing water and reducing breathability significantly even if the membrane underneath still keeps water out.

How do I reactivate DWR at home?

Wash the jacket with a specialist cleaner like Nikwax Tech Wash or Grangers Performance Wash — never use regular detergent. Then tumble dry on low heat for 20 minutes, or iron on low through a cloth. Heat reactivates the DWR polymer. Test by splashing water — it should bead and roll off instantly.

How often should I wash my Gore-Tex jacket?

Wash when visibly dirty or when DWR performance drops. Regular washing with specialist products maintains performance — body oils and dirt contaminate DWR faster than washing does. Most hikers wash 2–4 times per season. Always activate DWR with heat after washing.

What is the difference between wash-in and spray-on DWR?

Wash-in DWR (like Nikwax TX.Direct Wash-In) penetrates into the fabric and treats the whole garment including seams. Spray-on DWR is applied externally and is best for spot treatment or for jackets where wash-in could affect insulation loft. Both require heat activation. Wash-in tends to last longer but spray-on is easier to apply precisely.

When should I replace instead of re-treating?

Replace when you see delamination (bubbling or peeling of the inner fabric), when DWR treatments no longer restore beading after multiple attempts, or when the jacket is 5–8+ years old with heavy use. Some brands offer garment repair and professional re-DWR services as a cost-effective alternative to replacement.

Can I use a tumble dryer for an insulated jacket?

Yes — low heat tumble drying is safe and recommended for insulated jackets. Add two or three clean tennis balls to help restore down or synthetic loft. Never iron an insulated jacket — the fill material can melt or compress permanently. Ensure the jacket is completely dry before storing to prevent mould in down fill.