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As a gear tester, I strive to be as objective as possible. But I do have one bias: I love natural materials. Wool’s ability to hold warmth without overheating (and keep the inevitable stink down to boot). Bamboo’s soft-to-skin feel that somehow manages to last wash after wash. I’m even finally seeing the value of cotton after OL’s tests of the best canvas tents and the best hot tents.
Down is my favorite natural material. Impossibly light. Unbelievably warm. Compresses to nothing and then springs back again. All my cold-weather jackets are down (so are my kid’s), as are my sleeping bags. When I head out into the backcountry, I typically mix and match different weights of merino baselayers and down jacket fill powers depending on the forecast and what I plan to do. I even do this skiing, throwing a simple shell layer over my outer layers. For me, this system is more intuitive than having a dedicated “ski jacket” or “hiking jacket.” And I find down to be plenty versatile for the conditions I encounter.
But plenty of other people feel the exact opposite. For them, down’s inability to handle wet conditions makes it a non-starter. And I have experienced this difference first-hand. For instance, the original iteration of the ubiquitous Mountain Hardwear Ghost Whisperer would routinely wet-out along the cuffs; the updated version, which added synthetic insulation specifically at the cuffs, does not. Was my personal affection for down preventing me from experiencing similar benefits in other scenarios?
For me, the stumbling block was figuring out what weight or type of synthetic insulation to swap in for my down jackets. If you are a dedicated down user, learning the language of synthetics and eyeballing the relative warmth of different jackets is surprisingly confusing. So when Primaloft invited me to check out a wide swathe of products that use different types of their insulation — and declared their intention to challenge down head on in the process — I decided it was time to see if I could kick the down habit.
How Down Works
Down is the soft plumes that are underneath the outer feathers along the chest and belly of ducks and geese. It’s what keeps waterfowl warm, without weighing them down when they need to take flight. If you look at a piece of down, it has a single shaft off of which emerge many delicate strands that, unlike the aerodynamic outer feathers of a duck or goose, weave all over the place. The lack of structure to these feathers creates small air pockets, which creates a barrier between the outside temperature and your natural body heat.
Because geese and ducks have a layer of waterproof feathers that cover the down on their chest and abdomen, there is less need for these feathers to be waterproof. So while down does have some natural water resistance, it typically has not been enough to meet the needs of outdoorsmen and women in more extreme conditions.
Read Next: The Best Jackets for Extreme Cold
In recent years, companies have added various technical washes which gives down some limited ability to repel moisture. There are a few issues with this. The first is that this treatment strips the down’s natural water resistance away. Many of them are also temporary. And, several of these washes incorporate PFAS into them, which is now being banned in several states due to its environmental implications.
In my testing of the best down jackets, it’s been hard to pick out what is the water resistance protection being provided by the DWR treatment on the shell, versus what is the water resistance protection being provided by the down itself.
How Synthetics Work
Synthetics use the same fundamentals to create warmth as down: tiny pockets of trapped air that block cold temperatures. While synthetics, including Primaloft, are polyester at heart, they can vary the formulations and extrusion process to create different structures. Some synthetic insulation looks surprisingly like down. Others are sheets (called batting) that can be used to fill jackets without baffles. Some look like they’ve been knitted together.
The structure of synthetic insulation tends to be more rigid, so while it’s less packable than down, it’s also easier to wring out and reestablish those essential pockets. Primaloft also touted that their synthetic insulation resists water without the need for further treatment. To demonstrate this, they capped a cup of water with a layer of Primaloft, then turned it upside down. The water did not permeate the Primaloft to pass through to the bottom cup, even after sitting there for hours. This was fairly impressive, but when I gave the jar a gentle shake the water shifted and poured right through the material. So it’s unclear the extent to which this natural water resistance effect would come into play when paired as part of outdoor apparel.
In conversation with Primaloft, they were fairly bullish on the effectiveness of their insulation across a variety of needs and temperatures. “We try not to look at other synthetic insulation manufacturers as our primary competition,” said Ken Fisk, Senior Global Communications Manager for Primaloft. “We really focus on competing with down.”
Testing Primaloft Insulation Layers
I’ll be honest, I wasn’t able to get as much in-depth testing of the relative warmth of Primaloft’s gear done on the trip they invited me out on. Most of it was spent skiing and hiking on dry (and often sunny) Colorado mountain days. In my experience, high altitude sunshine is typically a lot warmer than the mercury shows. I didn’t even need the gloves Primaloft had provided for the trip.
When I got back to the damp and gloom of the Pacific Northwest, it was time to really put the half dozen coats in my carry-on to the test. After all, wet conditions are supposed to be what synthetic insulations excel at, and PNW is nothing if not wet. I took my go-to down jackets — the Big Agnes Luna, Crazy Levity, and Norrona Trollvegen — and put them in storage. Then, I replaced them with some jackets that seemed like their synthetic equivalents: the Rab Cirrus, the Helly Hansen Odin, and, because I needed something that would match the warmth of the Luna, both the Vuroi Hudson (a coat so puffy that it borders on parody) and the Black Diamond Belay Parka. I also committed myself to using the Strafe Lucky out on the ski slopes in place of my usual puffer jacket and rain jacket combo.
The results weren’t great. I spent most of the winter feeling pretty cold. Even skiing in temperatures that were technically warmer than what I had experienced in Colorado, I was cold. I often ended up doubling up on the lighter synthetic layers in an effort to avoid the bulk of the Hudson and Black Diamond jackets. The silver lining is that it confirmed a longstanding suspicion of mine, that while the mercury might run lower in Colorado, Western Washington is functionally colder.
The exception to this were the layers that I used while running. Layering for running in the Pacific Northwest in winter is a nightmare, because the median temperature is something like 35 degrees, usually accompanied by either drizzle or 80 percent humidity. But running is also a high exertion activity, especially if there are hills involved, so tossing on a down jacket and a rain jacket doesn’t work well. I usually opt for multiple layers of merino wool and then just delayer and relayer them as needed on the go. But the Primaloft jackets, specifically the Black Diamond First Light, breathed well enough and retained heat well enough that I could head out with just that and be happy for most of my run.
That jacket and many of the Primaloft layers I tested were designed as (and functioned as) mid layers rather than as true insulation layers. At best they were providing warmth on par with the Norrona Trollvegen, but nowhere near the Big Agnes Luna. Was my impression that synthetics ran colder more to do with how outdoor apparel designers made use of these materials?
Even the Black Diamond Belay Parka and Vuroi Hudson, which were warmer, were so heavy and cumbersome that it didn’t feel like a fair comparison, and frankly I tried to avoid wearing them. But looking at something like the Black Diamond Belay Parka and comparing it to the Big Agnes Luna isn’t really comparing apples to apples. The Big Agnes Luna is designed as a pure insulation layer. The Black Diamond is designed specifically for extreme climbing and mountaineering, complete with an oversized hood that your helmet would fit underneath.
This comes up a lot with synthetic insulation. When you’re looking for an all-purpose puffer jacket, down is the predominant choice. But as soon as you start getting into specialized equipment, synthetics start popping up. This even came up in staff writer Tyler Freel’s test of the best jackets for extreme cold, where a synthetic jacket, the Beyond Allta Parka, took top honors. Curious as to why they chose synthetic insulation over down, I queried Beyond to find out more about their reasoning. This is what they had to say:
“The tricky part about the Parka is that down wasn’t in the discussion at the time of build. This is due to the nature of the product. The Parka wasn’t built to be a highly compressible piece. Had it been, I think down would have been considered. Also, traditionally down loses insulation properties and ability to loft when wet, whereas synthetic is water resistant and can retain insulation properties.”
This has long been the conventional wisdom of down versus synthetics: Down is lighter and more packable, but synthetics are safer. But with today’s new breeds of hydrophobic down and increasingly competitive synthetics like Primaloft Gold, is this still true?
Why Comparing Down vs Primaloft Is So Tough
One thing that the down world and the synthetic world can agree on is that the way the other measures warmth isn’t applicable to them.
Down, as most outdoor users are familiar with, uses “fill power,” which is essentially a measurement of how much volume one ounce of down fills up. This is less a measurement of warmth then it is a measurement of weight to warmth. Higher fill power down needs less weight to generate the same amount of warmth, but you can always dial up warmth by simply adding more down. The tricky part is that while manufacturers are now quite dependable at showing what fill power down they are using, they do not reliably share information about how much of that particular fill power is in their jacket. So consumers are left with an incomplete picture of the relative warmth of a jacket.
Synthetic insulation uses a different system, known as Clo. This measurement is more akin to R value, as it’s looking at how well the insulation resists temperature changes. So a Clo of 1 is like wearing a light long-sleeve shirt indoors and a Clo of 3 is what you would need in one of the best cold-weather sleeping bags. So imagine the insulation sitting on a hot plate with a cold breeze going back and forth on the other side. How much energy does the hot plate need to use to maintain a consistent temperature? Like with R value, there are even standards for this test that Primaloft and other synthetic insulation makers use: ISO 11092 using a Sweating Guarded Hot Plate (SGHP) and ASTM C518 using a Heat Flow Meter.
What’s nice about these tests is that they provide a cleaner picture of how much warmth various insulations or garments are providing relative to one another. The problem is that virtually no one knows what they are, how to understand the numbers, or where to even find them. Primaloft primarily generates this data for outdoor apparel companies, and doesn’t post it on their website for consumers. It’s also not advertised on manufacturer garments, which is too bad, because it has the potential to be much more useful information to consumers than the particular brand name of the insulation being provided.
Primaloft told me that their Gold series is equivalent to 550 fill power down, which is based on a test of the two insulation types in pillows using ASTM C518. While this is bound to be of interest to gearheads, it’s not an ideal comparison for the purposes of apparel. That’s in part because down pillows tend to be overstuffed compared to quilts or comforters. It also doesn’t account for the comparative cold spots along the baffle seams of down jackets. But without knowing more about the weight to volume of the 550 fill power down here, it’s hard to say what effect either of these two issues would have had on this test. Primaloft is working on a new study to better compare the two insulations, but weren’t ready to share their results in time for this story’s publication.
Another useful way to compare the relative performance of down versus synthetic insulation is to look at sleeping bag temperature ratings. For Primaloft, this is actually pretty tricky: There are not that many sleeping bags using this insulation, and none that I could find that had official EN temperature ratings. Making things even trickier, fabrics for down sleeping bags are chosen in part to prevent too many of those feathers from poking through and escaping, something that isn’t an issue for synthetic insulation.
But, given all those caveats, let’s look at two 40-degree-rated sleeping bags from Big Agnes’s UL line. On the one hand, we have the 40-degree-rated V Notch sleeping bag that has 13 ounces of fill (Primaloft Silver) for a total weight of 1 pound, 6 ounces. On the other hand, there is the Pluton UL which has 8 ounces of fill (850 fill power down) for a total weight of 1 pound. The down sleeping bag here is almost twice the cost.
An easier apples to apples comparison is to look at Enlightened Equipment’s quilts, which use Climashield Apex as their synthetic insulation and 850 fill power or 950 fill power as their down insulation. They use the same construction for their down and synthetic quilts and you can order them at the same temperature ranges. The biggest difference between the synthetic and down quilts is that there are no baffles in the synthetic sleeping bag, due to the nature of the material. For their Revelation Sleeping Quilt, a 20-degree regular-sized model weighs 22.54 ounces and costs $345. Conversely, the Apex version of the same model weighs 30.14 ounces and costs $240. That’s a little less than 8 ounces, or a half a pound difference. And, again, a huge price jump for using down instead.
So I think it’s fair to say that on weight to warmth or warmth to packability, when dry, synthetics are not yet able to compete with down, especially given the prevalence of higher fill powers in the outdoor industry. But wet is another issue altogether.
Wet Down vs Wet Primaloft
I decided to run my own experiment to see how the latest and greatest in hydrophobic down treatment compared to some best-in-class synthetic when wet. For this test, I used the 14-ounce Rab Cirrus, which uses Primaloft Silver as its insulation, and the 9-ounce Marmot Hype Down. While the synthetic jacket is noticeably heavier than the down counterpart, it’s also about $100 cheaper. I chose these two to compare because they have similar baffle designs, puff when dry, and provide comparable amounts of warmth.
Because I wanted to make sure that the DWR treatments on the jackets weren’t clouding the results, I decided to completely soak both jackets, leaving them in a bathtub of water until the insulation was completely soaked through and could be wrung out. Then I hung them up for an hour to see how much loft they could achieve on their own while I headed out for a run. When I came back, I put one sleeve from each jacket on each of my arms.
It was clear, both from the relative amount of puff that each jacket was putting up, and from the relative warmth that was being captured, that the Primaloft Silver was providing the superior insulation. But the part of the test that most surprised me was just how difficult it was to soak these jackets in the first place. Back when I had the original iteration of the Ghost Whisperer, it took almost no effort at all to wet out the cuffs. With this new breed of jacket, it took hours, including me forcibly submerging the jackets only to have them spring right back up again.
Part of this is certainly that the DWR treatment (both PFAS free in this case) of today is just a lot better than it used to be, and it was taking a long time for water to penetrate that initial barrier. And while the Primaloft insulation did a superior job of lofting after becoming completely drenched, the down in the Marmot Hype — which was treated with a more permanent gold-particle tech called ExpedDry — did a heck of a lot better than I was expecting.
Environmental, Ethical, and Sustainability Considerations
The environmental and sustainability considerations around down and synthetics are even murkier than their relative weight to warmth considerations. Which is the more sustainable or the more ethical is debatable, but here are the basic facts.
Synthetic insulation in its raw form is polyester, which is derived from petroleum. Down comes from geese and ducks. On its face, that would appear to give down the clear lead, as the more sustainable option. But there is a darker side to down.
The down on ducks and geese is such a small percentage of the bird’s overall feathers that there is virtually no economic incentive to raise waterfowl for that purpose. So the down industry is supplied instead by the facilities and individuals that raise ducks and geese for consumption. This has long made down a non-starter for vegan companies and consumers, but there are other animal welfare considerations that continue to plague the down industry.
The majority of the world’s duck and goose consumption occurs in China, with France and Myanmar coming in at a very distant second and third. There has long been concerns that animal rights abuses are occurring in China as part of the harvesting of down; in particular, the live plucking of geese used for breeding. (Ducks and geese raised for meat do not live long enough to regrow their down, so live-plucking typically would not occur.) There is also the issue of purchasing down that comes from geese that were force fed for foie gras.
To help ensure that consumers could purchase garments where there was no animal rights abuse, the industry developed the Responsible Down Standard. However, down procurement facilities are allowed to sell RDS-certified down as well as down that hasn’t been vetted for animal rights abuses. The RDS standard also doesn’t look at the environmental impact of any treatments used on the down (such as those to imbue hydrophobia), which can also be harmful to the environment.
Synthetics conversely are naturally hydrophobic, no treatment required. Brands like Primaloft have also made significant strides in figuring out how to convert recycled plastics into the insulation they use, decreasing the environmental toll. But there is still, of course, a significant amount of energy needed to convert plastic bottles into down, so even synthetic insulation made from recycled materials is far from a net neutral on the environment. One way Primaloft has eliminated a big chunk of the energy is by updating the process for curing their insulation, up to 70 percent reduction in energy use. They also have factories scattered around the world, which helps to eliminate some of the carbon emissions associated with transport. Not all of their factories are equipped with this carbon-emission reduction technology, however.
In addition to having synthetic lines made from fully recycled material, there has also been a push in the world of synthetic to make their goods fully recyclable. Nemo is one company that has been at the forefront of this, with the first product in their Endless Promise series being a fully recyclable sleeping bag. Primaloft, since they are making a component part for a product, obviously has less control over how recyclable or not the entirety of a product is outside of their piece of the puzzle.
Down, you may be surprised to learn (I was), is also recyclable, it just doesn’t happen very often. And when it does, it’s typically only down comforters and pillows being recycled, not outdoor apparel. This is in large part due to the lack of demand for recycled down, compared to synthetics, despite the high price of down products compared to synthetics. To my mind, this is unfortunate, as there are plenty of times where a piece of down outdoor apparel will reach its end of life for reasons other than the degradation of the down itself (i.e., torn fabric).
Often proponents of down will point out that down apparel is better off being donated, given the potential longevity of the material. I have both a down winter-weight sleeping bag and down booties that are 50-year-old hand-me-downs from my dad, so I find this argument reasonably compelling. (Although I do worry about the quality of today’s apparel to last anywhere near this long.)
Finally, as a natural material, down will naturally biodegrade. This is a really tough area for synthetics to compete in and, full credit, Primaloft has made some huge strides. Their Bio line of synthetics breaks down faster than other options. After about a year and a half, over half of it will have broken down in a marine environment, while a whopping 86 percent will have broken down in a landfill. And its component parts are reasonably benign: carbon dioxide, methane, water, and biomass.
Unfortunately, these results won’t replicate the same way in a compost bin, due to the nature of the microbes that live there. That makes it harder for consumers to make a responsible choice — after all, adding a biodegradable garment to the toxic sludge of a landfill isn’t going to plug that garment back into the lifecycle of the natural world, and no one is realistically suggesting you toss your synthetic jacket into the ocean.
What Primaloft Does Best
Primaloft was originally created to provide lightweight, breathable insulation that would stay warm when wet, and this is still what it does best. If you’re going to be working up a sweat in cold, wet conditions, then go with synthetics. I’ll be continuing to run in Primaloft layers during Pacific Northwest winters. Watching how efficiently the Primaloft puffed back up after being completely soaked has also convinced me that it continues to be the right choice for extreme environments where there is no margin for error.
What Down Does Best
The packability and weight to warmth of down, especially premium down, is not yet matched by their synthetic counterparts. For a classic fall drizzle, hydrophobic down will keep you as warm or warmer than a similar weight synthetic jacket. Even in wetter situations with moderate exertion (like hiking or backpacking) I’d choose to layer a raincoat over a down jacket before choosing a heavier, bulkier synthetic jacket.
Final Thoughts
At the end of my testing and research for this story, the conventional wisdom prevailed. Although I was impressed at the extent to which hydrophobic down treatments and better synthetic formulations have closed the gap.
While I will continue to do my best to report out the relative warmth of different synthetic and puffer jackets, there are limitations to the amount I am able to cover in terms of the sheer number of puffer jackets on the market. I try to create objective tests that compare apples to apples but my conditions are far from the laboratory environments third party labs are able to replicate and the potential for subjectivity to creep through is always there.
Of course, it wasn’t that long ago that we were dealing with the same exact situation with sleeping bags as we are now for apparel. It wasn’t until 2005 that the first EN test for sleeping bags was created, and it was a few years more than that there were enough sleeping bags that had been tested for it to be a useful comparison. Is that test perfect? No, in fact, it’s a little ridiculous — a mannequin is dressed up and then put in a sleeping bag with a bunch of sensors attached to it.
Does it replicate real world conditions? Absolutely not, it’s a temperature controlled room that isn’t even all that cold. Are all sleeping bags tested for it? Nope again. It’s expensive, and it’s not mandated. But it’s also a miles better system than what we had before, which was different gear testers taking these bags into different temperatures and environments and then trying to compare their relative warmth.
Will we get something like that for apparel at some point? Right now it seems unlikely. With the current popularity of all things puff, the inherent price fluctuations of down, and the competing concerns of sustainability and animal welfare, there is clearly more than enough space in the market for both types of insulation. But for those of us looking for that perfect combination of weight, warmth, affordability, and weather resistance, the challenge is real. Plenty of people will look at what we know today about best in class synthetics and premium down and opt for the likes of Primaloft Gold. Personally, I’ll be sticking with down.
