I’ve been looking at a some down bags recently and after being asked some very difficult questions by the temperature and weather at the weekend, the Marmot Plasma 15 needs a mention.
The Plasma 15 comes in at 864g without a stuffsack and is one of Marmot’s top-end models. The 15 in the title refers to the Fahrenheit temperature rating which translates into -9ºC for the temperature lower limit for the Plasma making it useful for most of the year.
The form of Marmot sleeping bags is always good, the physical shape of the bag feels like they’ve thought about sleeping in it rather than trimming it to the verge of discomfort. That means it’s trim but there’s room to move your elbows and stick a knee out sideways a little, stuff like that is worth the extra grams.
They still keep the weight down by using Pertex Quantum fabric which is super light and soft making the bag compressible and pleasant to the touch and top quality 900fill down. The combination of this down and the light fabric means that the bags lofts very well, even after a few days compressed to death in a stuffsack, it just springs back.
I think the loft is helped by the unusual vertical baffles which run the full length of the bag. I certainly feels different in the bag, you get used to those seams across you where the Plasma feels seamless inside, it does feel different, very un-sleeping bag like and very comfortable. The tech reason for doing this is that the long baffles spread the heat from your warm core to your cooler extremities which sounds lovely, but to me it just sounds like your core’s going to have to work harder to pump heat into the bag as it gets sucked away to your knees, is it not better to insulate your core efficiently and have your knees warmed by your own heat pump (heart) and have the bag catch the lost heat at the source? Whatever, I like the baffle design, it’s very comfy and the bag is certainly warm.
A lot of work has gone into the hood and footbox. The big fish-lips around your face are comfy and make sure that when the hood is drawn in tight it retains a good shape, no untidy and annoying bumffling. The hood itself is very well scuplted and well insulated, you feel protected if you pull in it but because you can move your arms you don’t feel trussed up.
There hood drawcord has quite a tricky to reach external adjuster so it’s a bit of a faff to slacken, especially with gloves on, where I couldn’t even find it, which I often have when getting in my bag until I heat up properly, I’d change it for a bigger chunky cord lock.
There’s a big beefy shoulder baffle to seal in the heat if you like leaving the hood a little slacker. It’s closes right around you with two poppers and has a drawcord which is easy to get to grips with as it’s in beside you.
The footbox like the hood has a well thought-out shape, it’s fat, full of down and feet sit well inside it. I’ve used bags where your toes compress the fill so that they touch the outer fabric, getting the two ends of a sleeping bag are vital and it’s the areas that are a deal breaker for me, Marmot have got it right here.
There’s a nearly full-length two way zip on the Plasma which terminates cleverly in a curve with baffles around it so that pressure from movement won’t make it unzip while you’re sleeping and the zipper won’t come at your face when you flip over trying to shut out the sound on the wind and spindrift…
The zip has anti-snag detailing to stop it nicking the fabric, but I had problems with the zip, it jammed all the time. Now, I don’t mean on the fabric, it jammed on itself. I completely undid it several times in case I’d mismatched the two halves somehow, pulled it gently while holding the zip straight ahead of the puller, used one hand, different hands, both hands and it still jammed. I got increasingly frustrated with it and end up nipping a chunk of Pertex out of the inner with the zip while wrestling with it just trying to get out of the bag.
I hope it’s a one-off fault on my sample, maybe it would slacken off over time?
Pertex Quantum is tougher than it looks, over the years I’ve found it to have a good abrasion resistance if not great tear resistance, as witnessed again in the zip incident. The DWR is pretty good too, the bag was covered in snow several a times, it’s had a rain shower accidentally applied to it and several spills all of which I had plenty time to deal with before it soaked through. It a little damp it dries very quick too, so it’s a much more practical choice of fabric that you might think. Down is vulnerable to damp at camp, but so are you and we all seem to manage avoiding sitting in our tents in a pool of water, most of the time, so a bit of care and attention and your down gear is fine.
The Plasma 15 is a very nice bag, the shaping is excellent throughout and the fabric and down fill maximise the performance for the weight and packsize, which I didn’t mention as I never use the ones supplied with bags and because it’ll fit into the smallest compression sack I have, the orange eVent one from PODSacs, so it’s properly small.
Comfort and warmth is excellent but the niggles were disproportionately annoying, just getting in and out the bag became a task as I struggled with the zip and the drawcord.
So, recommended, but get inside it in the shop and make sure the zip runs smoothly.