Over stuffing bags

[MuleyFever]

What is the advantage to adding fill to a bag rather than just buying a warmer bag? I often see the option to add down when looking at bags but what's the point of buying a 30 deg bag and adding fill if you can just buy a 20 deg bag?

 

[BluMtn]

I still believe a liner would do more good that adding more fill. Does not take up as much room.

 

[Kevin_t]

Actually overstuffing can add a little in some bags , but really it keeps down from moving in the baffles and cold spots probably more than anything . Some, like Western Mountaineering are naturally overstuffed so overstuffing further may have a negligible effect . Some who skimp on down may see better results when overstuffed


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[MuleyFever]

But at that point why not just go with a warmer bag? That's my question. Why pay to overstuff a 20 deg bag rather that just buy the 10?

 

[Kevin_t]

True unless you like the cut of the 20 degree better than the 10 degree . Or if your mindset is you don’t want to feel like you are overkill like carrying a 10 degree bag in early archery . It’s actually sort of crazy the mindset ... some people want the smallest pack possible so they aren’t tempted to take extra ... some call and want our most durable pack fabric ... don’t really care at what level just the most durable so if we made tactical 1000 denier that would be it or if we topped out at 330 denier that would be it .




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[sneaky]

I think WM says that overfill adds about 5 degrees to their bag ratings, not the 10-15 that most people think. They say it prolongs the life of the down and avoids down shifting more so than doing it for warmth. Warmth in a down bag comes from the loft, not from cramming more down in the same space. Here's their chart from their FAQ page.

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[MuleyFever]

I think WM says that overfill adds about 5 degrees to their bag ratings, not the 10-15 that most people think. They say it prolongs the life of the down and avoids down shifting more so than doing it for warmth. Warmth in a down bag comes from the loft, not from cramming more down in the same space. Here's their chart from their FAQ page.

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Interesting. Thanks for posting that. It just doesn't seem like overfilling a 15 deg bag is any different than just buying the 10 if its the same bag with the same down the same material and same size. So the 10 would have more down essentially being an overfilled 15. I guess if the manufacturer only offered 20 and 10 you could get a 15 by overfilling a 20 if you just had to have a 15. Anyway, I guess that provides at least one reason to do it.

 

[Trial153]

I seen where over stuff was recomended for a quilt without a tapper to add more down to the a baffles. In other words the base amount was orginally for the tappered design.

 

[Kevin_t]

On a bag with continuous baffles you can always shake down to the top side which creates the same effect .

However in general terms is it depends on the manufacturer . Overfilling may be helpful on bags that are a little skimpy on down but on ones that are not skimpy it may have no effect .

The way WM does stuff they are naturally overstuffed . They calculate baffles based on 850 full down , BUT they buy the best down available likely 950 creating about a 12 percent overstuff or so .

Regarding temp rating and overfilling technically a 10 degree bag should have deeper baffles than say a 15 or 20 so it should take more down ... but it depends on the manufacturer and how they they fill it . A lot of dependencies and variables .

Myself I’d probably rather sleep in a 15 degree bag that the down did not move much vs a 5 degree that it did . I used to have a quilt years ago that developed cold spots every night from not having enough down .




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[tdot]

A 10 degree bag and 20 degree bag will be physically different. It isnt just the amount of down, it is also the space within the baffle that is different. The 10 degree might have 3" of loft and the 20 degree may only have 2.25" of loft. It is that space between that creates the warmth.

Over stuffing a bag will have a greater density of down within that given amount of space.

So an overstuffed 20, should not be the same thing as a 10.

 

[MuleyFever]

A 10 degree bag and 20 degree bag will be physically different. It isnt just the amount of down, it is also the space within the baffle that is different.

This would explain a lot then. If there is different construction then the down distribution would be different. Then overfilling could improve the distribution as mentioned above. My assumption was the only difference in bags of difference temp ratings was fill amount.