Sunday 18 November 2012

Z-Packs 20 Deg Down Sleeping Bag/Quilt Review

Note - I am a colder sleeper. This means that I need a bag rated at a cooler temperature than some to keep warm at any  given temperature. I know from many miserable, cold nights that I need to add 6 Celsius to an otherwise accurately rated bag. To be clear - If I want a bag to keep me warm at 0 Celsius then I need to be looking at bags rated around -6 Celsius. Bare that in mind when reading the review and particularly anything to do with temperature ratings. Unfortunately finding out if you are a cold or warm sleeper can be an expensive and sometimes cold experience! Quilts generally don’t have hoods and you will need additional head protection at cooler temperatures. I usually wear a light down hat when it's below 10 Celsius. When comparing quilts to hooded bags take that additional weight into consideration.

Commercial quilts have never really worked for me. My first experience was with a Nunatak Arc Ghost and while this is a fine example, as a side sleeper, I didn’t find it wide enough which made it a cold and draughty experience for me. I soon sold it on. Undeterred I started making my own and converted one of my PHD “design your own” bags into a wearable, hooded quilt. As this was a bag in its pervious life the width was far greater than is normal for commercial quilts. I found it worked so well that I converted my other 2 PHD bags into wearable quilts also. I was sold on the principle.

In Oct 11 I noticed that Z-Packs had released their own range of sleeping bags that were incredibly light for the quoted ratings. How could these bags be so much lighter than the competition? The weight of a bag for a given temperature rating can only change due to the materials, filling, design or size. All bags using similar materials and fillings, and of equivalent size, should weigh about the same. How then could these bags be so light? Was the temperature rating exaggerated? Perhaps they were extra small? No, the quoted fill and loft from the website looked accurate. Length was as you would expect. Width was excellent and material specification first-rate. How then was Z-Packs able to produce a bag so light for that given temperature rating? The only option remaining was the design. Intrigued I investigated further.

A standard bag from Z-Packs comes with a very light 0.7oz TenD nylon inner but a heavier 0.95oz Pertex Quantum nylon shell. 0.34oz cuben fibre baffles and 850fp down (since upgraded to 900fp US standard, which has less loft than the equivalent European rating) complete the specification. A unique feature is  its 3/4 length centre zip that you lay on. This allows you to close up and use as a bag when it's cold but open up like a quilt when warmer, best of both worlds perhaps? This sounded like a good idea but I hate zips! Zips are troublesome, unreliable devices that jam, snag and eventually fail.  I keep away from zips whenever possible. At that time a zipless bag, or quilt, wasn’t an option (it is now) and I wanted the bag to be as light as possible so I asked Joe if it would be possible to get a 20deg (-7 Celsius), long length, regular width, zipless bag with a 0.7oz TenD Shell instead of the Quantum. No problem he said! Cost was a reasonable $340 + $20 for those modifications + $29 shipping giving a total of $389 in 2011.

The bag arrived a couple of weeks later in a very nice black Cuben Fibre stuff sack, just in time for winter. As this was bought as a 0 Celsius 3 season thruhiking bag (read note at top) it only got used a couple of times before being put away until warmer weather. Those cool early tests did allow me to confirm that the temperature ratings specified on the website were accurate, which was pleasing, but it also showed up the one major flaw with this bag (read on). Weight of the bag was an impressive 480g and 20g for the stuff sack (not used). Total weight 500g compared to  an advertised weight of 513g.

Quality is excellent. Materials and construction are first rate. I’m picky here and I wasn’t able to find fault with the stitching or materials and after 60 nights of use on both my Scottish Cycling Tour and Coast & Moor hikes, along with some shorter trips, no manufacturing or material problems have shown up. Filling is harder to judge, loft is excellent but down leakage is about average. Many days there will be a feather or 2 sticking out of the fabric. I grab these from the opposite side and pull them bag into the bag; I don’t want to loose any precious down! The very light shell fabrics, or the quality of the down could be the cause of this leakage. My PHD bags almost never leak down even in the lightest MX fabrics, but previous bags from Nunatak and RAB leaked more down than the Z-Packs. Overall I would say the down is good but not as good as the exceptional PHD’s 900fp European down. Z-Packs are now using 900fp down which may or may not be of higher quality. One of the ways weight has been saved is by using Cuben Fibre for the baffles. I was slightly concerned how this would hold up long-term after repeated stuffing and un-stuffing into sacks, and also if it would attract condensation within the bag. So far there has been nothing to worry about, the baffles have held up fine and there has been no noticeable lofting problems caused by damp down. I do wonder how much weight is actually saved by this choice of material though. The light TenD shell and inner fabric isn’t showing any signs of wear and appears to be very breathable and resistant to minor water spills. I dislike waterproof shells on my bags, in my experience they resist lofting and the reduced breathability causes more dampness problems than it ever solves. I want the lightest, most breathable, shells available and the TenD fabric is certainly up there with the very best.

At 1.88cm and 69 kg I’m tall and skinny so went for a long length, regular width bag. As a side sleeper I have found the width to be excellent and it’s possible to get a draft free seal all the way around the quilt without much bother. This is the advantage of a quilt that’s been designed as a bag; they are just so much wider than normal! Length is just acceptable for me but ideally I would want another 3-5cm. The website recommends a long bag for individuals up to 6”2, or 185cm, well I’m 6”2 but 188cm! Those 3cm make a difference. If you are 188cm or taller then I would see about getting an even longer version.

Additional features are limited but it has an elasticated drawcord around the neck to keep out drafts. This uses Velcro to secure the two ends of the quilt together and I haven’t found it to work very well. Any movement would easily cause the 2 ends to pull apart so I added a mitten hook to the upper loops, which has been much more successful. Additional loops are fitted all the way down the quilt so it’s possible to link them all together and seal the quilt up very much like a bag if you should wish. I’ve not done this and no clips or cord are supplied.

So we know that the Z-Packs bags use high quality materials, sizing is overall very good and that the temperature rating is accurate. How then do they get it so light and what was the flaw that I mentioned earlier?

Z-Packs have saved weight by effectively removing the standard foot-box found on a conventional bag. It is tiny! If you are a back sleeper then I think this bag will not work for you as there is nowhere to put your feet without completely crushing the upper loft, and that will guarantee you cold feet.

As a side or front sleeper that isn’t so much a problem and I found that my feet naturally angled down into the bag without crushing the down much. Back sleepers beware! Also, and this is the flaw with this bag, there is an un-baffled, read - stitched through, seam running right across the lower foot-box of the bag. This really affects the warmth of the foot area when pushed near to its rated limit. On those early winter tests I had cold feet when the rest on me was still toasty warm. Before you write the Z-Packs bag off there is a solution and it is certainly possible to live with this flaw. Stuffing an item of spare clothing into the foot-box, or wearing some insulated socks if you are going to be pushing the bag works well. For me, I’m happy down to around 5 Celsius without any additional insulation but if I want to get the full 0 Celsius out of it then I need to push my down jacket into the foot-box.

In summary this is a high quality, premium material bag, that can be converted into an excellent quilt for side sleepers if wanted. The ratings are accurate but because of the design additional protection might be needed for your feet. Price is also good considering what you are getting. The weight is incredible for the rating but that comes at a price with that tiny foot-box. For my use, as a 3-season thruhiking bag that will normally be used in above freezing temperatures, then this is a compromise I’m willing to accept.


Joe from Z-Packs has commented that the problems I found with this quilt have been rectified. The foot-box is wider and now has a baffled seam. This is excellent news and takes this quilt to the top of the pile for me. 

But be warned...

Unfortunately this quilt suffered a blown seam on my cycle tour of Tasmania. Read this review in conjunction with this and make your own judgement.