GORE-TEX is made of a special mix of materials that you heat and cool to react with agent That process produces PTFE, material like Teflon, that you later stretch and tie with polymers to form ePTFE, a strong and thin waterproof layer that attaches to outer fabric. The heart of GORE-TEX is a thin membrane from expanded PTFE, like the nonstick material in frying pans.
The waterproof grade of fabric depends directly on its skill to last water under pressure during controlled laboratory tests. With higher resistance against pressed water, you rate it more highly. You measure the height at that water passes the material in millimeters (and that becomes the waterproof rating).
How GORE-TEX Works and Its Waterproof Ratings
For instance, if water penetrates at 15,000 mm, the garment recieves a rating of 15,000 mm waterproof.
Waterproofness ratings range from 5K to 45K and refer to the amount of water in one-inch column that should pass the fabric. Rating above 20,000 mm usually counts as sufficient protection against light to heavy rain. All GORE-TEX clothes are 28,000 mm.
During severe tests, GORE-TEX layers show a stable waterproof level of 28,000 mm hydrostatic pressure, which suffices to stay dry in many coarse situations.
GTX Pro, C-Knit and Paclite all have the same waterproof rating, measured by hydrostatic pressure at 28,000 mm. GORE-TEX does not use numerical ratings as other brands, but simply guarantees dryness, mostly because of marketing reasons. Breathability is rated typical between 15,000 and 25,000 g/m²/24h, where GORE-TEX Pro reach up to 25,000 g/m²/24h for intensive activities.
Not every GORE-TEX product is waterproof however. Only those with a black diamond come with the promise to stay dry. GORE-TEX INFINIUM products changed the situation, because they do not guarantee lasting waterproofness as the original series.
Many waterproof and windproof materials, like GORE-TEX INFINIUM, do not give precise values for waterproof and breathability ratings. The marketing that GORE-TEX is waterproof and breathable at the same time is a bit misleading, it does both, but not at the same time. Multi-layer materials with ePTFE are not only better than rubber raincoats in breathability, but also are entirely waterproof.
Technically GORE-TEX does not wear out, but the membrane stays tender. Excessive rubbing of the tied fabric can cause loss of waterproofness over time. Most brands like eVent, GORE-TEX or own gear clothes fall between 20,000 mm and 30,000 mm, a good base for reliable outdoor protection.
The GORE-TEX patent ended, so almost every outdoor clothingbrand now has its version of the technology.
