When sourcing cotton outdoor fabric, you must prioritize weather resistance and durability. Look for a fabric weight between 300-600 GSM for heavy-duty applications like awnings or upholstery. Ensure the fabric has undergone mercerization to improve strength and dye affinity. Crucially, verify the Water Repellency (AATCC 22) rating and UV Resistance (UPF 50+) to ensure the cotton fibers do not degrade under prolonged sun exposure. For commercial use, a Martindale abrasion test result of ≥20,000 rubs is recommended.