Montbell sleeping bag question

Nothing is perfect, just send it into someone who can stuff some more down in a few baffles, and therefore boost its rating.

I have the #3 (newer model) and my son has the older model #3 and we really like them. When you say that the baffles are completely devoid of down, that would be a serious manufacturing gaff that might happen in one instance but not in multiple bags as you have suggested. We have tested our bags down to their lower limit rating and they have been pretty accurate.

What I can say is that there may be two things happening… one is that you are comparing these bags to standard bags and that would be a mistake. The baffles in these bags are made larger than a standard bag to provide the "stretch" that they are famous for. Stretching out the baffle allows the down to move quite a bit and I have found cold spots in mine if I don't regularly redistribute the down. The fact that the baffles are larger than an equivalent "non-stretchy" bag means that the down will be less dense when the baffles are stretched out fully (I have noticed cold spots when I'm really stretching the bag to it's limits) but that problem is easy to resolve because the elastic used in the bag construction pulls the baffles in tight once I stop pushing on them (which concentrates the down) and the cold spots disappear.

The other issue is that Montbell made translucent baffles that allow you to see the down. I don't know of any other bags that do this, so how do you know it's really an issue (what are you comparing it to?)? I have held mine up to the light as well and can see thin spots. When I shake the down to redistribute it, it fills in the thin spots. The problem is that when you look at the baffle, you generally stretch it out to see the down distribution but the bag's (and baffles) optimum use will be with the baffles drawn in tight, not stretched out fully while you hold it up to the light.

I wonder if this issue would go away if Montbell used a material that wasn't see-through (you'd stop looking for problems and do a proper field test of the bag instead)?

Hi Mike,

Thanks much for your thoughtful reply. I'm heartened to read that you and your son have both had positive experiences with the bags down to their intended temperature ratings.

I should clarify a few points:

1) When I've found thin spots, it's been by holding the bag up to a bright light source without stretching the elastic thread.
2) I wrote that the baffles were "almost completely devoid of down", not entirely devoid. There were still perhaps 10-12 small tufts of down in the baffles in question.
3) Most important, though: I cannot re-distribute the down to these thinner sections of the bag. My understanding is that with its SS bags, Montbell doesn't use continuous baffles, but rather uses six chambers per baffle (top and bottom). These chambers seem to me to be sealed from their neighbors, as no amount of fiddling could shift the down from one section to another. Are your bags manufactured differently, or are you using the non-Spiral Stretch models?

I'm not expecting perfection in any piece of backpacking gear, but as you wrote, this problem seems like a rather persistent manufacturing flaw.

Cheers,
A

Andrew –

For clarification, the redistribution of down that I'm referring to is in each of the sealed tubes, especially at the widest (most stretchy) part of the bag. No, our bags do not allow down movement between tubes. I have experienced down shifting from on top of me to the sides of the bag (down migrates to each end of the tubes especially when the bag is stretched), which creates cold spots if I don't redistribute it occasionally back to the center of the tube. This generally means that I shake it up after taking out of the stuff sack and it's good for a few nights (it's not something I ever have to do during the night). If you don't have enough down to distribute throughout the tube then I agree you definitely have a manufacturing issue and I would not be happy with that either.

del

Hey Andrew,

I have owned a MBULSS #1 and #3 and have spent way more time than I should have trying to find a #2.

Mike pretty much nailed most of my thoughts in his above post.

I was also going to mention these thoughts:

You said you have tried four of them so far. Have you actually ordered four MBULSS backpacks and then held them up to a light and all four of them had baffles with zero down inside of them?? If so, that is something that should be made aware for others to check their own bags for. If that is the case, did you buy all four of them from the same shop in SF or did you buy them from online companies (same one, different ones) or did you get them direct? Basically just trying to hunt down if you have had a series of four from the same manufacturing run.

Regarding "the baffles aren't filled properly, how do you avoid cold spots".

Well as Mike said above, the MBULSS is not your traditional sleeping bag… the baffles are not going to be 100% filled with down. A number of my baffles are not even 10% filled with down, but because of the way that the baffles overlap each other when you are inside of it, it does not cause cold spots.

"I'm sure some people may interpret this post as inflammatory" — by on means. Totally legit questions and ones I asked myself the first time I put my first MBULSS up against a light.

Andrew,
After reading the review on this site, bought the spiral down hugger #3.
It remains perfectly filled with just enough down to fill out all areas of the bag.

Then came the reviews, posts and articles about the 'super' spiral line, and thought I had really missed the boat.

Since then, however, there have been a number of posts suggesting, like yours, that the supers don't completely fill out. Not sure what is going on here. There was an article here that compared, or at least had data on both the regulars and supers; but it did not fully resolve the issue.

At any rate, am happy with the not so super bag, never compress it except when carried in the pack in a large stuff sack with no compression straps, and when it gets rank, will launder it with Sportwash on the sweater cycle, and dry very slowly in the dryer with tennis balls. So far so good – much more warmth for weight than the synthetics used previously. With BPL cocoon PG top and bottoms, plus Thinsulate booties over sox, and BD fleece top and hat, it is comfy down to a few degrees below freezing; mid to high twenties, in other words.