sligowalkingclub

Chateau de Montbrun, Limousin, France

How to re-waterproof your Goretex jacket.

Info put  together for SWC by Stephen Clarke, who successfully re-waterproofed  his own GoreTex jacket. These methods also work for other breathable jacket materials, such as Lowe-Alpine’s Ceramic (or ordinary) Triple Point jackets. I got these methods off the internet and they seem to be tried and tested methods which work well.

Simple method 1, if your jacket is relatively new and not very dirty, SPRAY with NIKWAX  TX.DIRECT SPRAY-ON REPROOFING (£12 from Millet’s in Enniskillen or Call of the Wild). Follow instructions on the spray product, which essentially are as follows. Hang your garment from a hanger. Spray evenly and carefully. Spray it with the hood up. Allow to air dry. For better results, SPRAY it again. Spraying a garment manually is an inexact art. You don't want it to leak anywhere, so repeating the procedure increases the likelihood of thoroughly coating the whole thing. Air dry again. You don't have to worry about any harmful fumes: the product is water-based and about as eco-friendly as you can get. Pros are its simplicity and just one product. Cons are the difficulty of getting every inch evenly covered, and it’s not so effective spraying onto a dirty jacket.

Two-stage method 2, involving washing/soaking processes.

Pick up some NIKWAX Tech Wash nondetergent soap (£8?), and a bottle of NIKWAX TX.Direct wash-in reproofing, £11 from Millet’s in Enniskillen or a bit more from Call of the Wild. These products are not that cheap, but nor was your jacket and if it doesn’t keep the rain out it is pretty useless. You use the non-detergent soap in place of ordinary detergents which interfere with the waterproofing qualities of your jacket (biological washing powder is especially bad for GoreTex products and so are fabric conditioners). Follow instructions on these products, which essentially involves the following. Do a low temp (30 degrees) machine wash with NIKWAX Tech Wash, and ideally if you’re doing this machine wash rather than a hand wash, you should remove all trace of washing powder and fabric softener from the machine beforehand.The next stage, which can be done whilst the jacket is still damp from the first wash, involves steeping the jacket in a bowl mixed with a solution of the NIKWAX TX.Direct wash-in reproofing, stirring for good coverage, and then rinsing out and air-drying.

You will get excellent results that way, and leaving to air-dry is safer than tumble-drying on too high a temperature, which could destroy a lot of your jacket’s properties, but if you think you can be a very careful expert, you can slightly enhance the water-proofing by following an extra tumble-drying procedure.

MACHINE DRY on low heat. This step sets the finish. It takes the place of ironing (everyone should be afraid of ironing their GoreTex because the risk of damage is too high). A brief five minute tumble-dry on low heat for a GoreTex jacket can revive the waterproofing properties at any subsequent time, but if you are using your jacket regularly you might need to use method 1, or method 2, once or twice a year for best results.

Pros are that you get a completely rejuvenated jacket with all-over waterproofing. Cons are you have to buy two products, you have to take care following washing instructions and you do end up water-proofing the inside as well as the outside of your jacket, which apparently reduces its breathability. Some of us doubt about how much our jackets actually do breathe under Irish weather conditions even when they’re brand new.

For people interested in the science and technology behind these treatments I also found the following account on the internet from an article in Bayside Bushwalking Club's newsletter.

“Like many walkers, I chose a Gore-Tex jacket because it transfers moisture vapour, letting perspiration vapour escape before it condenses in the jacket making it as wet inside as outside. In the field however I have observed that while these jackets generally work very well, sometimes walkers complain that they get wet inside the coat because it did not breathe as expected. Curious about this I looked into what makes a Gore-Tex jacket work and what might cause it to misbehave. The demands placed on the jacket are high as strenuous activity can cause more than 1 litre per hour of perspiration which will overload any "breathable" fabric.

The Gore-Tex jacket is often a three layer garment having a ragged outer layer of Taslanised nylon or polyester, a waterproof middle layer of Gore-Tex and an inner protective Tricot layer.

Gore-Tex achieves it's breathable - waterproof qualities by virtue of having millions of small holes in an expanded Teflon (EPTFE) membrane. Moisture vapour passes from the warm air inside the jacket to the outside, even if the outside is under water. Water and wind is completely blocked and it resists water pressure of about 450 KPa (65 psi). The transfer is called Moisture Vapour Transfer (MVT) and requires that the air inside be warmer than outside and the Tricot layer inside aids the process by dispersing moisture from sweat that is then convened to vapour by body warmth. Gore-Tex functions better with fewer layers of clothing under the jacket and the more layers the poorer the breathability of your clothing system, so dress light, but warm.

When heavy rain flows in a sheet on the outside of any fabric it causes a temperature drop and vapour on the inside condenses. In a rain jacket this gives a clammy feeling. To minimise this the outer material is treated with a Durable Water Repellent (DWR) which is a Fluoropolymer applied under heat and pressure during manufacture. The DWR works by attaching tiny fluoropolymer "spikes" to the fibres of the fabric (where they stand on end like nails through dowel). The spikes are so close together that in effect the surface tension of the water holds it out from the fibre and it falls off. The DWR is not a plastic coating and does not block the gaps between the threads of the outer fabric or the Gore Tex membrane. Water can still pass between fibres of the outer fabric but it cannot saturate it so avoiding "sheeting" and the temperature drop that would cause condensation inside the garment.

From this it can be seen that the role of the DWR is vital to the performance of a Gore-Tex jacket and it must be kept clean and in good condition. Over time the DWR wears flat and requires rejuvenation or it may be contaminated and require cleaning. Some common contaminants that degrade the performance of the DWR are:

Smoke particles which are small enough to mask the DWR

Detergent which lowers the surface tension of water and masks the DWR.

Dirt

Oil. Gore-Tex is also affected by oil.

Fabric softeners which coat the material.

Salt water does not affect Gore-Tex but if it builds up in the jacket, like in any other breathable fabric it stores moisture giving a clammy feeling. The DWR is rejuvenated by heat but occasionally it must be re-applied when water drops no longer bead on the surface of a freshly cleaned garment. The clean garment should be treated with a Fluoropolymer water repellent. Silicone water repellents are not recommended as they are oil based. Be careful not to choose a waterproofing agent because this makes the garment non-breathable. A commonly available Fluoropolymer treatment is Grangers Superpruf spray but others are available (in UK and Ireland the NIKWAX range). These requirements are reflected in the cleaning instructions for a Gore-Tex garment that typically say:

Hand or machine wash warm with powdered detergent. No special soaps or detergents necessary. Use pre-wash stain treatment where required. Rinse well to remove all detergent (easier said than done).

DO NOT bleach or use fabric softener

Tumble dry or drip dry.

Steam iron on a warm setting to enhance water repellency.

P Drycleaning recommended. Request water repellent finish after drycleaning. (Drycleaners understand this symbol, Pereloethelyne).

Gore-Tex is not damaged by ironing, but take care not to melt the outer fabric (easier said than done) and test the iron on an inside hem and only iron when clean and dry.

A jacket needs cleaning it is smells of smoke, is dirty or sweat stained and complete removal of detergent is essential. Use heat after the cleaning process and re-apply the DWR when water no longer beads off the surface and use a Fluoropolymer, not Silicone to restore the DWR.”