So you spent a LOT of money on a high spec waterproof, the fabric is waterproof to several meters and treated with water repellancy and has a super-breathable construction but after a few outings it seems that performance isnt quite as you had imagined. Maybe you're still damp when working hard, sometimes sleeves wet out or the knees seem to leak perhaps ? Usually this is NOT because the garment isnt working correctly but CAN be because we are expecting it to do the impossible or the manufacturers figures are difficult to interpret...

I've covered some of this in an earlier article but an interesting email from a customer triggered me to re-visit this issue in a bit more depth as it affects many outdoors people and can be quite distressing when you feel a garment isnt working properly yet the manufacturer says differently.

Mark said: "I've found over the years with ALL so called waterproof clothing that once the DWR finish has degraded, no matter what you do ( Techwash and reproof etc etc) they're NEVER really proof anymore. I've had EVERYTHING from Haglof to Paramo, Musto,  Rab and its always the same. My gear gets a bashing as I have it not only for leisure but work also ( garden and landscaping) and breathability is also a big issue. No matter what the claims of the manufacturer- during work I'm really damp and clammy from sweat ( or in the case of my older gear) rain. A client of mine who is a great outdoors person says the same of her gear- after a year or so the proofness is gone. "

Mark has touched on several important points which are closely related and often confused:

1. DWR ( Durable Water Repellancy) - makes surface water ball up and roll off of the garment. This is the most obvious feature of a new wayterproof garment and is at its most impressive when you first use it in the rain, but this is a bit like the wax on your car and will gradually wear away.

2. Waterproofness - prevents water penetrating through the fabric to the wearer. Note that zips, collars, cuffs and other openings are rarely properly waterproofable so will present routes for water to enter the garment and are therefore excluded by manufacturers when they state a garment is waterproof. Waterproofness is measured by the height in meters of a column of water that will not pass though under the normal gravitational effect.  Most outdoor sport garments have hydrostatic heads of at least 5m, which is plenty for the majority of situations. However a 75Kg person seated puts and equivalent hydrostatic pressure of approx 2m to the fabric but kneeling can give pressures as high as 11m so under this condition it is possible for water to penetrate a perfectly functioning waterproof ! ( source: http://www.rustore.info/en/rustore/index.html)

3. Breathability - the ability of the fabric to pass water vapour from inside to outside to avoid build up of condensation. Measured as the volume of water in litres that can passed through one square meter of the fabric from the inside out in a 24 hour period. Bear in mind the measurement technique for this can have a dramatic effect on the result - vapour left to 'evaporate' upwards though the fabric is the most realistic test  The Upright Cup Test JIS L 1099 A1 but will result in lower figures than water vapour under even very modest gravitational pressure being 'pressed through' and will lead to higher water transmission rates, anything from 20-150% higher can be obtained with the The Inverted Cup Test JIS L 1099 B1 method which make for better headlines but dont necessarily give an accurate figure for practical use. There is even a test that simulates the heat of the human body The Sweating Hot Plate Test ISO 11092 which oddly is also flawed. The best thing for the consumer is to ensure that they are comparing like with like so that genuine comparisions between vapour transmission rates of various fabrics is genuinely comparable. Source: http://www.asfgroup.com/pages/components.html

4. Maintenance - looking after your garment to give it the longest possible lifespan with the highest possible performance

5. Performance expectations - being realistic about what a notionally 'perfect' garment could achieve will help bring perspective to just how marvellous modern fabrics really are.

Montane and RAB are brands we retail and both currently recommend regular treating with Nikwax TX direct to maintain the proofing of these type of garments. These comments also apply to many other brands with high performance fabrics for which DWR forms an integral part of the engineering.

DWR

The DWR issue that Mark hints at is that there are processes that are possible in a factory that are simply not practical at home so there is inevitably some compromise for home-applied products. That said, usually the performance after treatment is virtually identical although may not last quite as long as the factory applied DWR finish. I would suggest you treat the garment before the factory finish is depleted, also ensure that the key areas ( shoulders, under-arms and sides) are regularly treated long before they show signs of wetting out and the garment kept as clean as possible to avoid dirt abrasion prematurely depleting the surface treatments. Also ensure you store your garments on hangers to dry rather than keeping them squashed in your pack, possibly still damp. Together this should give you a much higher performance DWR for considerably longer.

Waterproofness

Its also worth pointing out that in the case of advanced fabrics like eVent and Entrant DT that these will remain totally waterproof even if there is no DWR. The issue is that without DWR the surface will wet-out and that in turn will prevent the breathability of the fabric working to its full capacity as there will be limited pores for moisture to escape through to the outside. In turn this can lead to a build up of condensation or vapour which is often mistaken as the fabric no longer being waterproof ( with cheaper garments that rely entirely on the DWR treatment providing the waterproofing may well be the case, but not with the branded fabics we are discussing here.) The key thing is that provided there is a reasonable amount of fabric that is not wetted out, and even the most basic of DWR treatments applied properly will give this effect, then the fabric itself can continue to breath and a build up of excess internal moisture should be avoided.  Another point is that a wetted out surface will feel colder on the inside of the garment, this too can be easily mistaken for a a leak and is indeed unpleasant.

Breathability

Another less openly discussed issue is that regardless of what fabric, no matter how breathable, all present a resistance to the flow of vapour, therefore if your work rate produces vapour in excess of the transmission rate of the fabic you will build up trapped vapour and start to become clammy. As an extreme example, even if one were completly naked but in a high humidity situation, even at low work rates it may not be possible to stay completely dry, so inevitably there are physical limits that simply cant be overcome in all situations. This is where the wicking properties of a good base layer are very important as that will provide a dry skin surface which will be considerably more comfy, even in extreme situations. Most people notice the wetting out issues on their forearms, usually in summer while wearing tees because there is no base layer to provide the wicking function. The other key place people tend to report is the back where a pack rests and therefore restricts airflow and garment breathability. Packs with raised or mesh backs are very helpful but will still have some detrimental effect.

Personally I wear long sleeve base layers all year and a very lightweight pack that hardly presses on my back and while the surface of my base layer does get slightly damp it is never uncomfortably wet.  When I want short sleeves I just roll up my sleeves, but this gives approach me the scope to get extra warmth from longer sleeves, or protect my arms from the sun and to ensure I stay comfy even in the worst of downpours while wearing any additional layers too.

Performance Expectations

Assuming you have read this far, you will now appreciate that the ultimate perfect 100% breathable 100% waterproof jacket will still get clammy under certain circumstances. Since technology hasnt quite perfected a fabric that reaches perfection there is a compromise that we must all respect. It is to do with the balance of whether it is better and more comfortable wearing our full waterproof layer or whether our rate of work and the ambient temperature and humidity is such that to do so presents limited advantages.

Summary

In a nutshell, all protective clothing has its limits and is therefore a tool to enable us to improve our well-being and performance in adverse conditions  and no single garment will ever manage to solve all the combinations of needs that we will throw at it. That said, some garments are MUCH better than others at meeting these challenges but to accurately compare one garment to another is not always as straight forward as it might first appear.