I've got a pretty good understanding of how GoreTex works.
I understand that the outside chemical coating effectivly holds water off the outer layer (using little chemical spikes).
But I can't quite seem to find out what the coating on the outside (when new) is? What's it's name or chemical symbols, etc?
the reason I'm asking (and is also a secondary question) is, do the standard replacement products (all of which are not made by GoreTex themselves) contain the same chemical, exactly?
The chemical coating on the outside when new is what is commonly known as DWR and chemically known as a Fluoropolymer. Fluoropolymer is a fluorocarbon based polymer with multiple strong carbon–fluorine bonds. It is characterized by a high resistance to solvents, acids, and bases.
This is the same chemical treatment used on all water resistant fabrics.
Gore-Tex uses this coating to prevent the outer layer of fabric from becoming saturated with water. This saturation, called 'wetting out,' can reduce the garment's breathability (moisture transport through the breathable membrane) and let water through.
As the DWR wears off over time, re-treatment is recommended when necessary.
Gore-Tex materials are usually based on thermomechanically expanded polytetrafluoroethylene and other fluoropolymer products. They are widely used in a variety of chemical applications, such as high-performance fabrics, medical implants, filter media, wire and cable insulation, gaskets and sealants. However, the most famous use of Gore-Tex fabrics is protective, but breathable, rainwear.
The simplest raincoat is a two-layer sandwich. The outer layer is usually woven nylon or polyester to provide strength. The inner layer is polyurethane (abbreviation: PU), which provides waterproof performance at the cost of breathability.
Early Gore-Tex fabrics replaced the inner layer of PU with a thin, porous fluoropolymer film (Teflon) coating that was glued to the fabric. This film has approximately 9 billion holes per square inch (approximately 1.4 billion holes per square centimeter). Each hole is about 1/2 million the size of a water droplet, which makes liquid water impenetrable, but still allows more volatile water vapor molecules to pass through.
The outer Gore-Tex fabric is coated on the outside with a durable water-repellent (DWR) treatment. DWR prevents the main outer layer from getting wet, which reduces the breathability of the entire fabric. However, DWR is not responsible for the waterproofing of the jacket. If there is no DWR, the outer layer will be soaked, and there will be no air permeability, and the sweat produced by the wearer inside will not evaporate, resulting in moisture inside. This may give a feeling of leaking fabric, but this is not the case. Abrasion and washing will reduce the performance of Gore-Tex fabrics because it will wear out this durable water repellent (DWR) treatment. DWR can be recovered by tumble drying or ironing at low temperature
Gore requires all clothes made of their materials to be taped at the seams to prevent the clothes from leaking. Gore's sister product, Windstopper, is similar to Gore-Tex in terms of wind and breathability. It can stretch but is not waterproof. The Gore naming system does not imply a specific technology or material, but a specific set of performance characteristics
