Down sleeping bag question

[JasonT]

I have had a Marmot Sierra down sleeping bag hanging in my closet for at least 25 years, and has only been used a couple times. I’m curious if the down will “go bad” over time or does it keep its insulating properties? Not sure if it’s worth hanging on to or if it needs to go in the trash?

 

[BRTreedogs]

As long as if lofts it’s good to go.
If the down is clumped up and won’t loft it won’t insulate well.

Dry it with a couple tennis balls and give it a use

 

[35WhelenAI]

Yep, agree with above. Try the balls and see how it lofts up, if differently at all, from what it is after hanging for 25 years.

Also could proactively wash it with any of the good down wash products on the market, dry it and see what you get.

For what it's worth, I have a 12-year-old REI radiant 20° down bag. I use it two or three weeks a year, I have washed it twice in that time. Most recently after 2025 archery and rifle seasons in Colorado. Not that it had lost any warmth however it is as lofty as it was when new.