Fabric Coating, FYI     Hydrophilic vs. Microporous Coating  Dry vs. Wet Processing  Waterproof vs. Splash-proof
 

Fabric Coating, FYI
	As the great outdoor enriches people's life and health, the demand on comfortable outdoor wear has reached an all time high.  Clothing for outdoor activities is very different than those wear indoor.  Mostly, outdoor clothing demands for additional functions such as waterproof, windproof, permeability, warmth, durability, softness and being  skin-friendly.  The following is a brief introduction to various coating techniques and processes for your better understanding.
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Hydrophilic vs. Microporous Coating
Waterproof and Permeability Fabric Coating:  A process which applies formulated compound on clothing to form one or multiple membrane layers in order to achieve porous waterproof as well as improves the appearance of the fabric.  It's commonly applied in two distinctive coating types:  Hydrophilic and microporous coating.  In terms of processing, it's also divided into either dry or wet processing method. 　    Hydrophilic Coating （exampled by PU resin compound）：  Utilizing the unique characteristics of "moisture-friendly" functional molecules in the PU polymer chain to achieve its permeability.  Its permeability is less than the microporous coating, by comparison.  At the molecule level, the PU resin polymer attracts and absorbs H2O from the high humidity side of the fabric (the side closer to the skin) and releases H2O on the other side.  Permeability is thus achieve by the absorb-penetrate-release cycle.  The pores in the membrane have the size of 0.01 µm or less so it has the waterproof characteristics as well.  It tends to have a smooth and soft finish, durable against washing, waterproof even under pressured water.  However, it does have a drawback that the membrane expands when wet and thus is susceptible to scratches. 　    Microporous Coating： Microporous coating coats fabrics with  formulated solutions that forms a membrane with micropores.  Each micropore has a diameter of 2 µm or less.  It blocks the penetration of water droplets (e.g., rain, fog, mist) which has diameters about 100 µm but at the same time allows moisture vapor (such as from human skin) to go through.  Microporous coating can be manufactured by either dry or wet processing method.  It has high permeability, is skin-friendly and able to keep fabric soft.  It can also be further processed with fluoride protection to be splash-proof and against wash.  Compared to hydrophilic coating, microporous coating is more complex and generally has a higher processing cost.
Hydrophilic and Microporous Combo Coating： Hydrophilic coating is added to the microporous membrane to take advantage of the best of both world.
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Dry vs. Wet Processing
Dry Processing Method:  Dry processing applies formulated coating solution on the base fabric then dry the solution at various, controlled temperatures.  Coating layer is formed either with pores or poreless.  　    Wet Processing Method： Wet processing is similar to dry processing but instead of drying in a controlled temperature, it was emerged in water then dried.  While in the water, the DMF in PU polymer was replaced by water molecules and left with micropores when dried.  Micropores formed in this process has a honeycomb and interconnected structure with pore in the 0.5 to 2 µm diameter, to be waterproof and breathable.  Wet processing yields stable quality, coating is durable and so far is the best method in coating outdoor clothing.
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Waterproof vs. Splash-proof
After certain coating process, the fabric can be "splash-proof", in withhold waterproof quality under certain water pressure.  In stead of absorbing water droplets, it forms water drops on the coated surface and skids off.  The waterproof coating is relatively simple in processing and generally at a lower cost.  However, waterproof coating is not necessarily breathable.
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