There are no set qualifications that make a certain fabric suitable to be used outdoors rather than indoors. There are, however certain specifications that as a collective group render a textile more suitable to be used on outdoor applications. The textile must be solution dyed, exhibit high lightfastness, and must be mildew resistant. Without these three basic qualities the textile will be unable to withstand nature’s elements.
The solution dye process is when the pigment or dye is added into the spinning solution/polymer before it is forced through the spinneret, dispersing the color evenly throughout the fiber and producing excellent colorfastness and consistency (http://www.contracttextiles.org/index.php?page=s). Since the solution dye process produces such superior colorfastness it plays a crucial role in the integrity of the finished textile will determine what types of fibers can and cannot be used. Natural fibers cannot be solution dyed for obvious reasons; therefore only manufactured fibers can be used. Nylon, acrylic or polypropelene and polyester are all examples of fibers that can be solution dyed.
Lightfastness is just what it seems it is. Lightfastness is a textile’s degree of resistance to exposure to sunlight (http://www.contracttextiles.org/index.php?page=l). In other words the lightfastness term refers to how well a certain textile retains its color when continually exposed to sunlight. Once again it is clear why a textile must be solution dyed to begin with.
Lastly the textile must be mildew resistant. Mildew resistance is a fabric’s ability to resist mold and mildew. Fabric can be chemically treated so that the performance characteristics are not adversely affected if the fabric is exposed to moisture for long periods of time (http://www.contracttextiles.org/index.php?page=m). Another way to achieve mildew resistance is to extrapolate silver’s natural anti-microbial properties and integrate it within fibers to be used in outdoor applications as well as in medical textiles and even your workout garments.