This recent thread ( Bandana 48″ x 48″ ) reminded me of another bandana-related challenge — besides sourcing desired-size and quality material: how to speed-up the softening process, rather than waiting on repeated use and washings.
Search of past EDCF threads found one old, brief discussion.
My experience, no matter where I’ve bought — stiff as cardboard, and the 400-grit sandpaper I use in the shop isn’t as rough as a new bandana (I exaggerate only slightly). This, due to the “sizing” used in the manufacturing process. So I’ve resorted to boiling for half-hour or so, despite nagging feeling this might “harm” the fabric (although I see boiling often recommended).
Other recommendations on the web to accelerate softening process, none of which I’ve tried yet: soak or wash in mixture of water and 1/2-cup fabric softener; or use white vinegar (or borax, or salt) in place of the softener. And the more exotic suggestions: substitute one cup non-fat dry milk for soap; add small rocks or tennis balls while tumbling in the dryer. Latter two not considered for even nano-second. Mrs. X would skin me alive. 
Anyone tried one of these methods, with success?