What is waterproof ?
So you might ask, what is waterproof ? Waterproof seems like a simple terminology that is relatively self explanatory, in a fashion similar to the word “DEAD”, there are no varying degrees of dead, one dead parrot is no more dead than the next dead parrot, they are both deceased. Waterproof, however is an umbrella(see what I did there?) term, which can range from barely water resistant to 100% waterproof. When talking about waterproof clothing the term “waterproof” can be used to describe fabrics which will resist penetration from water, there are varying degrees of resistance, this is usually denoted by the “hydrostatic head”. This is a scientific process for gauging how much water a fabric can hold out in a 24 hour period. The test is basically a piece of the fabric in question, which has been bracketed onto the bottom of a cylindrical head which is marked with volume indicators, a millimetre will represent a millilitre. So if the fabric can resist say 3000mm then it is said to have a 3000mm hydrostatic head, 3000 would be at the lower end of the scale with 10,000 being considered more water resistant. So, if we believe what the trading standards set as being acceptable levels of water resistance then we can conclude that if it holds out a bit of water for a while then it may be described as waterproof, but that there are varying degrees of “waterproofness”. I try to avoid describing articles as waterproof, even though they may be labelled this, I would give them a description based on their level of water penetration resistance, going from moderately water resistant to being able to hold out all day. There are other standards for indicating levels of water resistant and are generally clearly marked on the labels of Personal Protection Equipment (PPE) which will generally be used in the working environment are denoted with a numbering system which scales from 1-3, 1 being not so water resistant and 3 being very highly water resistant. These numbers are relevant when health and safety is involved, the higher the number the longer an individual can wear their protective equipment in heavier rain or exposure to water. This scale also incorporates a second number scale 1-3 which denotes how much water vapour can be transferred through the fabric, 1 would indicate that little or no vapour will pass whilst 3 will indicate that the water vapour can pass through more easily, thus the garment could be described as “breathable”. Breathable is another one of these terms which has a set of scales or measurements to indicate the levels of breathability. Breathable fabrics are described as Moisture Vapour Permeable(MVP) and their levels of vapour permeability are measured by strict scientific tests and adhere to specifications set out by bodies governing such issues.
Requirements of the individual will differ, factors such as activity level, degree of precipitation and length of exposure must be considered when choosing the correct product to fulfill your requirements. In my experience there is no perfect membrane which will provide all the answers, but a decent compromise can be achieved, here in the North of Ireland and climates which are generally mild but moist/damp, breathable is not the most important factor to consider, if there is a real threat of extreme cold exposure then this is when breathable will become a big factor as sweat must be able to escape from the clothing otherwise the cold can get into insulating layers which could lead to hypothermia and possibly death. In extremes of cold waterproof is a requirement but is not as essential as breathability, in milder wetter weather breathable is desired but will ultimately not make the difference between life and death, in a downpour it is better to keep the rain out than worry about a bit of sweat on your back. With outdoor attire it is best have all the layers in the right order and made from the correct fabrics in order to achieve the most comfortable experience, but if a lot of rain and a bit of cold bother you, then stay indoors.