The Nikwax Waterproofing Down Proof can be used on sleeping bags and it will make it somewhat waterproof.|â€¢Adds / renews water repellency and revives breathability|â€¢Maintains insulation, keeping you warm|â€¢Minimises weight gain|1.For sleeping bags immerse item(s) in hand hot water in a bowl or bath tub. |2.Apply by hand, agitate and leave to soak for 5 to 10 minutes. |3.Rinse under running water, drain and gently press the sleeping bag to expel excess water. |4.To dry, and only if care label allows, spin dry 3 times and tumble dry on a high setting until all â€˜clumpsâ€™ have disappeared. |5.Use clean tennis balls or trainers (that wonâ€™t melt) in a clean pillow case to help break up clumps when drying.