Overstuffing Down Sleeping Bags?

You ask if anyone else has asked WM to add down to a bag.  I have.  Details..

I own a Megalite in the long version.   It could be 5-10 years old and lightly used. I also own a Feathered Friends Kestrel “30” bag in a regular size it is slightly older than the FF and lightly used.  I find that neither bag is particularly warm at 30 degrees.  I probably sleep a little cold, but nowhere near as cold as a typical female.  I’m 6 feet tall, 170 lbs.

Because both the Megalite and the Kestrel were not as warm as I would prefer I recently contacted Western Mountaineering re: adding down.  WM said no way, they won’t do that anymore.

I contacted FF with a slightly different ask – I believe the main reason that the Kestrel is less warm than the Megalite (which has less loft than the Kestrel) is because the Kestrel does not have an effective collar.  The megalite does have a good collar. So, I asked FF if they would add a collar and extra down.  Answer: Nope.  I did have FF add down to my Lark shortly after I purchased it (a year or three) but in this case I was asking for more than just down; namely a collar.

IMO both bags could easily handle additional down without being materially “overstuffed”. I would simply call it “additional fill”.

On one overnight backpacking trip with my son we had both bags and the Megalite was warmer than the Kestrel even though the Megalite is baggier and the loft measures somewhat lower than the Kestrel.  I own a few other bags.  Back to the Megalite – I froze on that trip – it was the Goat Rocks Wilderness in early August.  About 6,000 elevation. Cloudy and foggy, with daytime drizzle and breeze. Temps estimated to be in low 30’s at night but above freezing.  I started with the Kestrel on the first night but switched to the Megalite the next night and I was warmer in the Megalite (not a perfect test by any means, so it may be that both bags are roughly equal in a better side by side test). My son who is 6 foot 2 or 3 and 210 lbs was comfortable in either bag.  It is hard to be warm in the 35 degree fog…

Later, I contacted one of our favorite boutiques to see if they would add a collar to the Kestrel. Answer: Nope.

I think both WM and FF more or less said that if I didn’t find the bags suitable for the target conditions, I would be better off selling them and buying new ones designed to be warmer.  They might be right, but I would be happier to pay $100 or so to just have more down put in both bags (and a collar in the Kestrel) rather than going through the headache of selling my existing bags and buying new ones – and I know the incremental cost would be a LOT more than $100 per bag.

I agree with your assessment that often a 20 degree bag is a better choice for “mountains” in the summer than one with a 30 rating.  Especially if you only have one or two bags. I have many bags so having a 30 degree bag has its place.

I wish I could overstuff my own sleeping bag but how would you open up the baffles without ruining the bag?

Depends on how it is built.

WM and I suspect others fill their baffles from one end, and then they close it up with a top stitch, so theoretically if you wanted to do it your self, you could just locate the topstitch used to close up the baffles, rip that seam open, fill the baffles, and then rerun the topstitch. You’d have to have some basic sewing machine and some MYOG skills and a little patience. And down.

Locally it costs $99- to open a bag up and add 100g of 850FP down. Except for my UL summit bag when new, I’ve never bought or owned a bag that didn’t benefit from that top-up. This includes my brand new S2S Traveller2 which is going in soon. Most companies add only enough down to loft sufficiently to maximise loft. This amount is usually well be low the optimum fill amount.
The only companies I know of that did use the optimum amount of fill was the now defunct Arthur Ellis of New Zealand; Fairydown brand; think Hillary on Everest in 1952 etc and Australias Mountain Designs, now sadly just a brand name and no longer owned and run by climbers
EDIT
If I was buying a new sleeping bag or down filled clothing and I was able to specify extra down I would opt for at least 10% over nominal and depending on circumstances and proposed use 15% would not be too much. My Everest duvet [ never used there ] has a 50% overfill by design, to resist wind compression and degradation over time

I am a cold sleeper, so overfilling is something that I tend to do on my cold weather bags to get them to their advertised temp rating.

I currently have two Feathered Friends cold weather bags and both were ordered with overfill.

The first is a Raven 10 UL that uses 950+ fill. I requested 3 extra ounces of 950+ fill when I ordered it. The cost was $19.50 per ounce, so $58.50 extra total.

The second is an Eider EX -10 that uses 900+ fill. I also requested 3 extra ounces of 900+ fill when I ordered it. The cost was $17.50 per ounce, so $52.50 extra total.

I am not sure if Feathered Friends will fill their bags after the fact. Even if they did in the past, I bet they have stopped that practice at least for now with the whole pandemic thing.

Since I am a cold sleeper, having that overfill in my cold bags is key for me. For others that actually make their own body heat, it may not be as important.

I have always found Feathered Friends to have excellent customer service so if you have specific questions about any of their stuff, or what services that can provide you, just give them a call at 206-292-2210.

Wow major bummer if WM won’t  add overfill anymore I’d been thinking about sending a couple bags in recently. WM recommends tenacious tape and considers it a permanent repair and with the black tape that’s more cloth like I agree. The clear patches work well also which I’ve done in the field b4 but the black is better. WARNING READERS MAY FIND THE FOLLOWING IDEA OFFENSIVE AND MAYBE EVEN PAINFUL TO READ. Here goes I don’t think I’d do this with my -20 with V block side baffles but my megalite with continuous baffles I’m thinking about just putting a small cut in each baffle on the outside bottom of the bag which is black divide 2-3ish oz of down  between 15 baffles and tape shut with a bunch of oval patches. I’m not worried about resale and I have a lot of confidence in black tenacious tape. $10 for 2-20” rolls of tape + the cost of down. What do you think be honest I’m good at taking verbal abuse.

Mark that’s a really bad idea.

They sew a sleeping bag and then they fill it. The trick is to find the openings.

Follow the advice of Michael B.

Sometimes it can be where the zipper is placed.

It depends on the construction.

The top stitch should be pretty noticeable. I had a look at one of their  Astralite quilts in the shop over thanksgiving, and their top stitching was done on the insides of the footbox liner and up and down the sides – I imagine it is the same for their bags as well. It would be super easy to use a seam ripper, or even an exacto, if you are really careful. It is a little tedious to loosen up the stitching, but pretty straight forward. Then just use some clips and sew it back shut when you are done adding the magic.

I’ve found the seams where they are top stitched and I can use a ripping tool it’s my ability to sew it back up that’s the problem

needle, thread and patience

Got two out of three

I would suggest buying a yard of light weight rip stop to practice on. Take note of the stitching  dimensions and fabric stack up on the seam on your bag, and practice recreating that topstitch on the scraps. You don’t want to punch a bunch of extra holes in your down bag if you don’t need to.

If you don’t have a machine, I suggest hitting up your local Craigslist or thrift store, there are usually several out there for next to nothing, and it will most definitely help keep tight and consistent stitching which you will want to keep all the magic in the bag.

AHA! Rob P. says his FF bag was “ordered with overfill”. Good idea.

-> Wm now makes its Megalite with a collar. Nice. And I do believe WM will make it “overfilled”.

TheMegalite has NO side baffle. This is done so you can shake down from top to bottom and vice-versa, depending on temperature. BUT… if you order it overfilled you will no longer be able to shift the down from top to bottom. So what? At least it would be a true 20 F. bag if factory overfilled at the time of manufacture.

Yes, you can get many of the Western Mountaineering bags with factory overfill.

The Hermit’s Hut (https://hermitshut.com/) is the place to buy WM bags with factory overfill. They include the factory overfill option on the bags they sell at no extra charge. Plus they have great customer service.

The Hermit’s Hut does offer the Megalite with the free overfill. It comes with an extra 2 ounces of fill.

One difference between FF and WM when it comes to overfill is FF will do what you request where as WM has a specific amount of overfill they will put in each bag. You don’t get to pick what amount you want.

Here are the WM factory overfill specifications:

Foot Box Overfill (any bag), Tamarack – 1.5oz – $27.00
MityLite, SummerLite, MegaLite, UltraLite, Alder MF, Sycamore MF, Apache MF & GWS – 2oz – $32.00
TerraLite, AlpinLite, VersaLite, Badger MF & GWS, Antelope MF & GWS, Ponderosa MF, – 3oz – $48.00
Sequoia MF & GWS, Kodiak MF & GWS, Lynx MF & GWS – 4oz – $60.00
Bristlecone MF, Puma MF & GWS, Cypress GWS, Bison GWS – 5oz – $78.00

This info is from the WM FAQ page.

Reading the WM pages I see that you have to order the footbox stuffing as an extra; it would be a real PITA to have the new bag arrive with the footbox not as warm as the rest of the bag.

We’ve had 9 different WM bags in our house going back to 1992. Currently have 3. All ordered from Hermit’s Hut, all with overfill.

+1 on Hermits hut.   Free overfill on pretty much every WM bag.   The only ones they don’t are those that don’t have it as a factory option like the quilts and Highlite.

I guess I’m a bit confused regarding down overfill. In all my research on overfill I came to the conclusion that it was beneficial for side sleepers (which I am) as it prevented down migration minimizing cold spots but only increased temperature rating by a few degrees at best (and this came from individuals at WM and FF). Even if you add a few ounces of overfill the baffle height remains the same so the amount of loft, regardless of amount of down, therefore will remain roughly the same.

The WM Megalite 30F, Regular Length, 64″X 56″ X 39″ w/ 12 oz of down + 2 oz overfill =    14 oz fill with a baffle height of 4″ w/ top collar

The WM  Aplinlite 20F, Regular Length, 64″ X 56″ X 39″ w/ 19 oz of down with a baffle height of 5.5″ w/ full collar.

If the Alpinlite is 20F with having 5 oz more down than the Megalite with overfill, each having the same dimensions, than how can the Megalite have a 10F temperature gain while keeping the same baffle height? The Alpinlite 20F and Versalite 10F (versalite is slightly slimmer) have roughly the same amount of down (1 ounce difference) but the Versalite has a 1″ greater baffle height (6.5″ to 5.5″)….

Please educate me as I assumed that the baffle height limited loft regardless of the amount of fill. Thanks :-)

As of note I always order overfill to prevent down migration as I toss and turn from side to side….but not to increase the temperature rating of a bag.

I hope I explain this correctly, but this is how I see it. See images below.

The standard fill at a nominal fill produces a baffle shape shown in red. The parameters to consider are the baffle cross-sectional area, baffle height, and baffle length.

When this baffle is overfilled, it will definitely increase the total loft, but it will also cause the baffle to form a more cylindrical shape (green lines). This is good because it will cause the baffles to retain their shape and down migration is less likely to occur, causing fewer cold spots. If the down is compromised with moisture or is in need of cleaning, the extra fill will mitigate a loss in nominal loft in those cases, causing the bag to be more warm.

The overfilling can cause the baffle length to contract, since as the loft is pushing out on the shell and liner and closer approximate a cylindrical shape, the baffles will be pulled closer together(it is trying to equalize the pressure it is exerting on inner baffle, shell and liner surfaces). This will effectively make the bag shorter, but that may or may not be a big deal depending on the user size relative to the bag.

When you move to a bag rated to lower temperature, you are effectively increasing the cross-sectional area of the baffle without increasing the circularity of the baffle (see orange lines). This is accomplished by taller baffles. This is just going to make the bag that much more insulated.

I am a little confused by the wording of your question, Turley, but the graph below and my wording would explain why overfill can have the effect it does. I tried to draw as accurate as I could to show the differences, but then I decided it was easier to just draw it in CAD. The CAD shows the area differences between the 3.

1) a nominal 2″tall x 4″wide baffle produces a nominal 8sqin cross-sectional area

2) that same baffle overfilled to produce a 3″ nominal loft produces a cross-sectional area of 10.235 sqin, but at the expense of .175″ of length. This produces a more robust loft for sure than the nominal square baffle, less likely to shift and produce cold spots. But there are the baffle areas which are still only 2″ high, so that is going to produce less warmth than number 3 due to reduced cross-sectional insulation area

3) nominal 3″ tall x 4″ length baffle produces a nominal 12 sqin cross-sectional area.

This is the difference between an overfilled bag vs a bag made for colder temps. From a user perspective, you may not notice much of a difference, and this is going to vary from person to person, but a bag with larger bafffles that are sized and filled properly to maintain down in the areas where it is needed ( we won’t talk about poorly designed or underfilled baffles, those are obviously not worth discussing here) will insulate better than an overfilled bag with shorter baffles. The CAD shows pretty easily why. I hope it is helpful.

I can see your point where overfill will add a few degrees….but with two additional oz in a Megalite it seems a stretch to acquire a full ten degree temperature rating change. Upon talking with WM and FF representatives they stated it will add a few degrees at best…

Who was stating that overfill adds 10deg? Maybe I missed something. The math for insulation is not difficult, but the baffle design can affect the way the down works. The only way I could see overfilling adding 10deg warmth is if the standard fill provided is not correct for the baffle design. If you have widely spaced baffles, then overfilling is going to increase the loft more than a bag with more narrowly spaced baffles, for the reasons I mentioned in the examples I gave. What WM and FF told you seems to be in line with the graphics and numbers I showed.  The whole notion of temp ratings is subjective anyway, so I don’t usually go by that until I have an established standard that I can compare to. I.e. I know how much insulation I had on top of me when I froze my butt off on New Year’s Eve, so I know I’ll need more than that the next time I go out in those conditions.

Initial post: “Several years ago, after barely being warm enough on a 24 F. night in a 30 F. WM Maglite down bag on the PCT that I sent the bag back to be overstuffed by Western Mountaineering for a paltry $40. Well worth it to make it into easily a 20 F. bag.”

I agree with a few degrees as overfill will increase loft slightly but more importantly prevent cold spots….and that how one sleeps, either warm or cold, is uniquely individual….but a 10F difference is substantial and wouldn’t expect to get that with a few ounces of overfill.