Nikwax Down Proof 10 oz.

My old sleeping bag had gone flat and clammy after a few seasons, but one cycle with this stuff perked the loft right back up. It goes in the drum just like detergent, no spraying or soaking, and the down doesn't clump afterward. Completely revived a bag I was about to replace.

Washed my down jacket with this and the loft came back better than I expected, no clumping at all. It's a washing machine treatment, which I was nervous about, but the water beaded right off in the rain afterward.

Took my down sleeping bag from sad and flat to fluffy and shower-proof in one machine cycle. Measured out the capfuls easily and the bottle says it treats a duvet, so I’m planning to use it on our comforter next weekend.