Rating Rain JacketsObviously the most important things about rain jackets are how well they keep out water and how well they get water vapor out of the jacket. People have devised some pretty cool tests in textile laboratories to quantify how waterproof rain jackets are, or how much vapor they transmit. However, life rarely mimics a laboratory. The fact that you, a human being, are putting on a rain jacket and living your life means that you should take all the rating with a grain of salt.
Waterproof RatingsThe most ubiquitous laboratory test for waterproofness is the Hydrostatic Head Test (HH). This test involves placing an empty tube against the fabric to be tested. Water is then added to the tube slowly. The more water is added, the more pressure is applied to the fabric. The rating is the height (in millimeters) of the water inside the tube when it finally penetrates the fabric. The higher the number, the more waterproof the fabric.
|0-10,000mm||This is a weak rating. Clothing in this category can be called water resistant or weather resistant, but it isn’t usually referred to as “waterproof.”|
|10,000-20,000mm||10,000mm is the threshhold for waterproofness. Clothing in this range is waterproof in moderate conditions. These are ideal for casual sporting.|
|20,000-30,000mm||Clothing with ratings in this category offers the highest degree of protection. These are ideal for use in extreme conditions, or when staying very dry is of utmost importance.|
Breathability RatingsThere are a number of breathability ratings available, but the most common is g/m2/24h, which refers to the mass of water vapor that can pass through a square meter of the material in 24 hours. A high score means more vapor from perspiration can escape the jacket. The more water vapor transmission, the more suitable the fabric is for strenuous activity. Of course, washing your waterproof helps maintain breathability and waterproofness over time.
|0-10,000 g/m2/24h||Best suited for light to low-moderate activity. Sitting, standing, easy walks, and easy skiing.|
|10,000-15,000 g/m2/24h||Moderate to high-moderate activity. Hiking, difficult skiing, extended travel.|
|15,000+ g/m2/24h||Able to handle high levels of activity or humidity. Clearing trails, snow-shoveling, tropical travel.|