Zud/Naptha/TSP
Zud or Barkeepers Friend cleansers are found in the grocery store, are cheap and both contain oxalic acid as the active ingredient. This organic acid will chemically reduce rust stains and the green verdigris from bronze fittings without damaging the fabric or threads. Paste with water, soak and scrub with a soft brush.Naptha/lighter fluid will remove most grease stains. Rinse with soapy water before a final clear rinseWitch's Brew for sail cleaning. To a 2-gal bucket of water add 1 cup of boat soap, 1/4 cup of TSP powder (Tri-sodiumphosfate), 1/4 cup of Oxalic Acid powder. Apply, scrub with soft brush, rinse with fresh water, apply, scrub again, rinse, rinse, rinse, rinse and let sun dry. (courtesy of Brian Cleverly)