Top buying tips for waterproof clothing
THERE are a number of ways to waterproof a garment but what does ‘waterproof’ actually mean? How waterproof and breathable is a garment and how is it affected by the weather? On cold days or in cold water for example, there can be more condensation between the warm, dry inner body and the cold exterior and – without good insulation between the two – this can cause heavy condensation on the inside. Similarly, on warm muggy days, evaporation is less efficient and the temperature, plus any physical activity, will play a massive part in the effectiveness of any breathable clothing. As a standard for waterproofness, there are laboratory tests that measure the height in millimetres (mm) of water ‘head’ that can be upheld before the water penetrates through a garment. Breathability is measured as the ‘water transition rate’ that can pass through a membrane in grams of water (in vapour form) per square metre of fabric per 24-hour period (g/m2/24hrs or just ‘g’). All good clothing manufacturers will have a label somewhere or specify the lab ‘head tests’ in their literature for their particular materials – beware the manufacturer that does not! Generally a garment that can suspend a metre (1000mm - head) of water, without allowing any to pass through, may be deemed as being ‘waterproof’. But typically, a good average waterproof/breathable product will use material exhibiting a head of 3-4000mm, and a breathability of 3-4000g/m²/24hrs too. A garment with 10 metres (10,000mm head) of water lab test specification, could be expected to be 2.5 times more ‘waterproof’ than 4000mm material. But that does not always apply as weather, wear, choice of under/outer garments, zips, seam taping etc and how well made, can and will have an impact on the performance. On warm muggy days, garments will also be less efficient at evaporation for breathability and excessive sweating can occur beneath too. Simple temperature variances will have an impact on performance and once condensation forms it will not transmit through a waterproof, breathable membrane. Higher specification waterproof and breathable material can be as much as 20,000mm (20 metres) and more and 20,000g/m²/24hrs, but still needs to be well made to be properly effective. Gore-Tex is an example of high spec material and others like the new five-layer Snowbee Geo waders are also in this bracket. Other products like the Prestige breathable waterproofs are extremely reliable and specified at 8000mm waterproof and 4000g breathability, which is still highly efficient and represents superb value. Snowbee incorporate a TPU Vapour-Tec® system that enhances moisture/vapour migration out through the membrane of the garment too.
WHAT TO LOOK OUT FOR
Check the labels and watch for evidence of good manufacture like neat stitching, double-hemmed seams properly taped inside, seams that do not run into pockets which can hold water, plus zips that are protected. A good fit is essential as is room for a sensible synthetic wicking layering system beneath, which helps prevent condensation. Plus, look for cuffs that are close fitting or neoprene, that will stop water running down the sleeves when casting in a jacket. Garments must fit well and have no stress points, which will encourage leaks over time. Waders can be the worst for problems like this if they are ill-fitting. Modern fabrics have come a long way and whilst traditional stalking outfits for example, have been made for many years from a good wool weave, some of today's advanced synthetic materials can be so much lighter and more efficient, and so well treated that they are very resistant to penetration by water and wetting and very breathable too. The material fibres of today can be treated with a number of waterresistant dressings that when weaved together can be hugely advanced in their properties. This coating can break down over time though and if left wet for any length of time can encourage bacteria that can destroy a garment or waterproof membrane. Some can be fully dried and retreated but best to look after it and keep the garment clean and as new for best and most reliable results.
WHAT IS DWR?
Durable water repellent (DWR) refers to an outer coating to fabric that can be added to help the fabric become more water-resistant. Good DWR treated clothing will bead up on the outside when new and less so once starting to wear. This helps prevent saturation of a garment from the outside, regardless of the material properties. Without it, even with a waterproof inner membrane, the outer can still become very heavy and is called ‘wetting out’. Water soaks up on the outer surface, despite a membrane beneath keeping the wearer mostly dry inside. Breathability, however, becomes significantly reduced when this happens. This DWR finish does wear off over time and when it does, re-treatment is recommended using a spray or wash-in product.
Make sure you're prepared for whatever the weather throws at you.