Loosen all zippers and draw cords on your sleeping bag. Fill your bath/large basin with lukewarm water and add Nikwax down wash as per the specific instructions on the bottle, and ensure the Nikwax mixture is evenly dispersed throughout the tub. Carefully submerge your sleeping bag in the tub/basin.
For an extremely dirty sleeping bag, first focus on dirt spots with a clean soft-bristle toothbrush (using gentle, circular movements to remove tough stains) and Nikwax down cleaner. Leave to soak for an hour, after which you can drain the water and replace the tub with fresh water. Remove excess soap by gently massaging it (take care not to wring or squeeze, this will damage the down). Repeat this step until all soap is gone and the water is clear.
Drain all water from the basin/tub and gently massage the sleeping bag to remove excess water. Take care to support the bottom of your sleeping bag when removing it from the tub/basin as down is heavier when wet which can cause seams to stretch and tear unnecessarily if not supported adequately. Lay your down sleeping bag on a flat, smooth surface to air dry for a few minutes and take care to once again ‘massage’ the down to ensure it is evenly dispersed throughout the sleeping bag. Tumble dry on a low heat for no more than 15minutes at a time. Be sure to add two regular tennis balls to your dryer to assist with the even dispersing of the down. Take your sleeping bag out of the tumble dryer after 15 minutes and re-check that the down filling is evenly dispersed. Repeat until dry (this may take several hours, ensuring you’re occupied for almost a day) and leave your sleeping bag open during the night in a protected area to ensure it is 100% dry.