Revive Synthetic Sleeping Bag?

They’ve given their all.

Have you ever washed them ?

(most likely too old but you never know…)

Yes, washed and hung dry.

Tumble drying on a low setting has the best chance of reviving your old synthetic bags. Usually achieves something, though they will never be as warm as they were when new. BUT BEWARE! tumble drying on too hot of a setting will kill them permanently, so keep it warm but not hot.

Paul-Thanks. I will try that.  Does synthetic insulation loft of old vs new have any relevance?

I’ve mentioned elsewhere that I’ve seen old synthetic insulation regain much or all of its loft after washing and lots of tumbling in the dryer.  My old Holofill MYOG vest (Frostline I think) from the 1970s regained almost all of its loft, I was quite surprised.

there was another thread recently about this

I believe dryer balls (like tennis balls) were also suggested

If you can measure loft, the thickness is pretty close to proportional to warmth

Elliott- Was the tumbling without heat? Did you include any tennis balls during this?

Brad – I recall I tumble dried on low heat, then kept tumbling w/o heat for some length of time, don’t recall how long.  I put a few tennis balls in there, too (now I have real wool dryer balls).  Recently I’ve been tumbling down garments in the dryer with dryer balls but w/o heat to help restore loft, works pretty well.

Big structural and density differences between “state of the art” 1970s synthetic insulation and more recent stuff. In my experience and others, the old insulation was heavier but lasted much longer.

I have an early 1980s North Face synthetic bag in the back of my truck that’s still plenty warm today – but weighs about 5 pounds. Yet my early 2000s North Face synthetic bag of supposedly comparable warmth and roughly 3 pounds isn’t even usable as a couch comforter now, because it’s lost so much loft.

Nothing to lose by washing and drying with tennis balls.

YMMV.

— Rex

Weird because I seem to recall reading somewhere that tennis balls was a bad idea with synthetics.

As I understood it, tennis balls are good for down because it helps break up the down clumps that form when down is washed.  On the other hand, tennis balls only serve to hammer the synthetic fibers, causing more damage and loft degradation.

Now I’m wishing I could find where I read that.

hmmm…  that makes sense

not necessarily the authority: https://www.rei.com/learn/expert-advice/caring-sleeping-bag.html

In the instructions for washing down and synthetic bags:

“When a down bag is nearly dry, add two or three clean tennis balls (or a lightweight pair of clean sneakers) to the dryer. This will help break up any clumps of down as it spins and will help restore the loft.”

So that would imply not to use dryer balls on synthetic.  Maybe it just doesn’t matter.

With wet down you get clumps you have to break up.  With synthetic you have bats that are sewn to the face fabric so there are no clumps to break up.

https://outdoors.campmor.com/how-to-wash-sleeping-bag/ and https://protips.dickssportinggoods.com/sports-and-activities/camping-and-hiking/how-to-clean-your-sleeping-bag say to use tennis balls for both down and synthetic

https://www.backpacker.com/gear/how-do-i-clean-my-sleeping-bag the same as REI

what you would need to do is controlled experiment, some synthetic bags use tennis balls, some not.  over many years see if there’s a difference in loft.  Nobody’s going to do that : )

Never thought about tennis balls w/synthetics, maybe I shouldn’t be using them.  Seems to me they sort of gently beat the insulation to help fluff it up, but maybe that breaks the insulation down.  And it’s a good point that older synthetic insulation was much tougher (and heavier) than modern synthetic insulation, which really can’t take the beating by the tennis balls.   So I’m thinking maybe no dryer balls when I get around to washing my vests and other gear made with modern insulation.

BTW I have two vintage REI 550 FP down winter bags from around 1979 that weigh about 5 lbs each, rated to -20 degF if I recall.  They are stored lightly stuffed in large breathable sacks.  They still seem to loft up good as new.  Down is amazing in this respect, even my vintage 1973 Camp 7 down jacket lofts up like new (I washed it once or twice over the decades).  Alas it barely fits me any more, my wife and kids mostly get use it.