Introduction
What’s the most versatile ultralight gear item you own? Chances are good it’s your ultralight down jacket. An ultralight down jacket, weighing less than 14 ounces (397 g), is truly multi-purpose gear – wear it in camp to stay warm, wear it in your sleeping bag to extend its range, wear it on cold weather day trips, put it on when you reach the summit, wear it après ski, and wear it on a trip to town. Same jacket, many uses.
Why down? Because it’s very lightweight and has the highest warmth-to-weight ratio, it retains its loft and can last a lifetime, and it’s highly compressible. Synthetic insulations are steadily improving, and do have a few advantages over down – they are water resistant and insulate when wet, they dry quickly, they are easier to care for, and they are cheaper. But the disadvantages are significant: synthetic insulations break down with repeated stuffing, synthetic insulated jackets are distinctly heavier (with a few exceptions), and their cost is not that much different from a down jacket. The bottom line is: when you want the most warmth with the least weight, go with down.
It seems like nearly every outdoor apparel manufacturer has an ultralight three-season down jacket these days. There are definitely a lot more of them around since our last review of lightweight down jackets in 2005.
This is the last of three coordinated articles reviewing the insulated components of an ultralight sleeping system, consisting of an ultralight three-season down mummy bag, down pants, and a three-season down jacket (broken into three separate articles).
The complete set of articles in this series is:
The Conditions
An ultralight down jacket is a core component of an ultralight backpacking kit. It’s amazingly versatile and useful the year ’round. PHD Ultra Down Pullover worn in camp at 12,000 feet (3,658 m) on a chilly evening whilst summer backpacking in the southern Colorado Rockies.
The conditions targeted for the articles in this series are three-season outings where colder (but not frigid) nighttime conditions will be encountered. Three-season means three seasons – spring, summer, and fall. Sometimes the “three-season” adjective gets misconstrued as “warmer weather” or “summer,” but that’s not correct. The spring season is often windy and stormy, and nighttime temperatures can drop below freezing. Fall days can be balmy, but the temperature really drops at night. And in the mountains, we can experience three seasons in a single day! Jackets designed for three-season use need to withstand wind and the chill factor that comes with it, as well as cold rain and snow.
Note when I say “outings,” I am primarily thinking of backpacking, but the gear and techniques recommended here are equally applicable to ultralight biking, paddling, climbing, and adventure racing.
As you will notice in this article and the jacket reviews, we tested these jackets throughout the winter. Yes, they may be called “three-season” down jackets, but they are also just the right amount of warmth for active pursuits in the winter as well, which is part of why these jackets are so versatile.
Technique
Key components for an ultralight sleeping system for colder conditions, such as camping in an igloo as shown here, are an ultralight three-season down mummy-style sleeping bag, down pants, and down jacket. Gear shown is the Sierra Designs Nitro 30 sleeping bag, Eastern Mountain Sports Ascent Sector Down Sweater, and PHD Minimus Down Trousers.
The goal for an ultralight sleeping system is to minimize weight while providing the versatility to stay warm, dry, and comfortable in moderately cold conditions. The sleeping system should consist of a sleeping bag that is warm enough for the expected nighttime temperatures most of the time, plus an ultralight down jacket and pants that will keep you warm in camp and can also be worn in the sleeping bag to extend its warmth for the occasional colder than expected night. We save weight using this system instead of carrying a furnace – a 15 to 20 F/-9 to -7 C rated bag – that’s overkill in both warmth and weight. While conventional backpackers carry a warmer/heavier sleeping bag to ensure they stay warm, experienced ultralight backpackers carry the sleeping system described and stay warm while saving weight.
These jackets perform exceptionally well as either an outer layer or midlayer. As an outer layer in cool conditions, they are very wind and water resistant and provide the right amount of warmth for active pursuits like hiking. In camp, wearing a windshirt or shell jacket over a lightweight down jacket significantly increases its warmth by reducing heat loss through the seams and trapping heat inside.
What’s a Three-Season Ultralight Down Jacket?
To be considered ultralight, a down jacket should be insulated with high-loft down, the shell fabric should be very lightweight with a good Durable Water Repellent (DWR) treatment, and features should be minimal and lightweight. The cutoff weight for jackets included in this state-of-the-market report is 14 ounces (397 g). Down jackets heavier than 14 ounces are more suited to mountaineering and winter camping, rather than three-season conditions.
The down quality standard to earn an honest “ultralight” claim has risen to 800 fill-power (fill-power is the volume one ounce/28.4 grams of down will expand to fill). Some manufacturers use 850+ fill-power down, and the highest quality down currently available is 900 fill-power. The latter is scarce and expensive because most down is a by-product of geese raised for meat, and that’s as good as it gets under present conditions. Note that some good bargains can be found in jackets insulated with 700 fill-power down, if the jacket is constructed of lightweight materials and you’re okay with a little extra weight.
Premium shell fabrics weighing from 0.74 to 1.3 ounces per square yard (25-45 g/m2) are used on most ultralight jackets, usually tightly woven nylon or polyester ripstop calendered for strength. Calendering is a process where the fabric passes between rollers where temperature, pressure, and tension can be applied in varying amounts to either side to enhance fabric and seam strength, downproofness, and wind resistance, but it decreases breathability. The process makes the fabric shiny, so many manufacturers have their shell fabric calendered more on the inside and less on the outside. Overall, technical differences in shell and lining fabrics among these high-end jackets are small and hard to relate to any clear differences in field performance. They differ mainly in weight. Greater differences exist between the shell fabrics on these high-end jackets and less expensive jackets.
Finally, the shell fabrics on all of these jackets have a Durable Water Repellent (DWR) finish, which makes them very water-repellent. Nearly all factory-applied treatments are fluoropolymers, which are related to Teflon. They chemically bond to the fabric, so they will withstand many trips through the washing machine without being washed off. The newest technologies apply the chemistry in the vapor phase using chemical vapor deposition, which can apply a nano-thin layer that minimizes any impact the coating may have on the look or feel of the fabric. A DWR treatment typically adds 0.1 oz/yd2 (3.4 g/m2) to the fabric’s weight.
Not All Ultralight Down Jackets are Created Equal
Ultralight down three-season jackets abound! We found a lot more that meet our criteria (high-loft down, ultralight shell, weight under 14 ounces/397 grams) than we expected. The thirty-one jackets included in this State-of-the-Market report cover the full gamut, from Spartan to full-featured. Among the jackets that qualify, there are large differences in weight, loft, warmth, sizing, and features. The “ideal” down jacket depends on what you are looking for, and hopefully this state-of-the-market report will help you find a good match.
Ultralight down jackets are available across the warmth scale. The MontBell Ex Light Down Jacket (left) at 5.7 ounces (162 g) and the Feathered Friends Hyperion Jacket (right) at 11 ounces (312 g) have the same loft-to-weight ratio, but they are at opposite ends of the warmth scale.
Deciding what features to add to an “ultralight” jacket is a tough call for outdoor gear manufacturers. When you look at it from their point of view, realistically, more jackets are sold to outdoorsy people who wear them daily to work, socialize, and play. The mainstream market is for a different kind of multi-use: outdoor fashion plus outdoor recreation. These jackets have more features and nuances to attract buyers – like more pockets, recycled content, and attractive styling (especially in the women’s version of these jackets). And some manufacturers take it a step further with zippered fleece-lined hand pockets, a zippered chest pocket or inside pocket, a fleece-lined collar, and a drawcord hem.
A separate market exists for jackets that are truly designed for ultralight outdoor endeavors (that’s us). These jackets (fewer in number) are designed to attain a high warmth-to-weight ratio and to provide as much functionality as possible with minimal weight. The quandary is still there – whether to add hand pockets and a full front zipper, for example – but manufacturers minimize weight as much as possible when they do add these features. Some manufacturers have settled on an “essential feature set” that “most consumers want” – consisting of a full front zipper, zipperless hand pockets, and elastic cuffs and hem – and they provide those features while keeping weight to a minimum. Another reality is that there is an even smaller market for a pullover style jacket (anorak) or one with no pockets, even though those designs reduce weight, so those styles are less common
The Loft Conundrum
While most manufacturers reveal the quality and quantity of down in a sleeping bag, they only advertise the down quality in jackets. Only a few manufacturers list the fill weight (amount of down in the jacket) in their jacket specifications. Most manufacturers will provide that information upon request, so it’s not a closely guarded secret. I requested it from all of the manufacturers and that data is listed in our specifications when it was provided. Manufacturers do not specify jacket loft. They avoid the loft issue because of its complex, conflicting, and confusing relationship to jacket warmth: (1) loft is an elusive spec to measure (it’s a moving target) and (2) loft is not directly correlated to warmth.
Case in point: the MontBell Alpine Light Down Jacket (left) contains 4 ounces (113 g) of down and has a single-layer loft of 1.3 inches (3.3 cm), while the Rab Microlight Jacket (right) contains 4.4 ounces (125 g) of down and loft of 0.9 inch (2.3 cm). The down in the Rab jacket is compressed in its smaller quilts to make the jacket less bulky.
In the Backpacking Light forums, reader Richard Nisley reports his personal research on the thermal performance of outdoor apparel in an effort to overcome the common misconception that loft equals warmth. Research by Richard and others has found that down can be compressed as much as 2.5 times without losing its thermal efficiency. The old notion that down needs to fully lofted (allowed to expand as much as possible) for maximum warmth is not correct, according to Richard’s findings. In fact, it can be partially compressed into a smaller volume without any loss of insulating value.
Taking this one step further, the amount of down in a jacket is more directly related to the jacket’s warmth than the loft of the jacket. Jackets do not have to be designed so the down is allowed to fully loft; it can be packed more densely or partially compressed in the jacket’s shell, and the jacket will be just as warm (though it is true that many manufacturers do allow the down to more fully expand so the jacket looks puffier, because puffier jackets are perceived by buyers to be warmer jackets).
How can this be? Richard’s “new paradigm for understanding garment warmth” runs counter to the old adage that dead air space within the down’s matrix insulates because the thermal conductivity of air is much lower than solid materials. After all, we measure down quality by fill-power – the volume that one ounce of down expands to – and higher quality down expands more and traps more air. Thus, one would think that compressing down means less dead air space, which means less insulation.
It doesn’t actually work that way, says Richard. By his own measurements, using a guarded hot plate which measures the cumulative heat conductivity from all modes of transmission (conduction, convection, and radiation), he has shown that down can be compressed up to 2.5 times without any loss of thermal efficiency. Richard’s explanation is as follows: “When down is uncompressed, convection is normally a negligible transmission factor. And conduction and radiation are the primary heat transmission modes. As the down is progressively compressed, the conductive heat transmission increases but the radiation transmission decreases. Over an approximate range of 2.5x density variance, the net result is approximately the same insulation value.”
Another way to understand how this works is to compare compressed down with Aerogel. Aerogel is a nanotechnology that creates numerous minuscule air pockets within a lightweight matrix, giving it extremely low density and thermal conductivity. Compressing down is analogous to this; the air pockets become smaller, but the thermal conductivity changes very little. Higher fill-power downs are more filamentous and create a low density highly porous matrix following the Aerogel analogy.
The lack of any easy method to measure jacket warmth makes it a much more difficult tool for comparison. For example, two jackets containing the same fill weight laid side by side can have a distinct difference in loft, but no difference in warmth. The consumer doesn’t have any good way to determine which garments are the warmest. The situation with garments and sleeping bags in the U.S. today is the same as it was with sleeping bags in Europe prior to the EN 13537 standard, which requires manufacturers to subject their bags to an independent standardized test. The only truly accurate measure of jacket warmth is standardized testing performed by a testing lab. In spite of the obvious benefits to the consumer, many manufacturers benefit from keeping the situation ambiguous; the only manufacturers who would benefit from having independent tests are the ones whose products test the best. So, what’s a consumer to do? Since measured loft is not the best indicator to determine jacket warmth, the only meaningful data left is the amount of down in the jacket, and that information is often not readily available.
Baffles and Quilts
The majority of these jackets have single-quilt (sewn-through) construction, which saves a little weight and is less expensive. Of the thirty-one jackets in this roundup, the only jacket constructed with baffles (like a sleeping bag) is the Nunatak Skaha. The MontBell Permafrost jacket has “welded single quilt construction,” which is functionally equivalent to sewn-through construction. Welded construction is used to avoid stitching through the jacket’s Gore Windstopper laminated shell. Jackets with single-quilt construction vary widely in quilt size and design. Narrow quilts as small as 1.5 inches (3.8 cm) hold the down in place and provide less room for expansion, wider quilts up to 4 inches (10 cm) provide more room for down expansion resulting in a puffier (and presumed warmer jacket).
The amount of quilting in ultralight jackets varies widely. For example, the Crux Halo Top (left) has a small checkered pattern, while the Western Mountaineering Flight Jacket (right) has a wide horizontal pattern. Narrow quilts hold the down in place and compress the down to some extent, while wider quilts provide more room for down expansion resulting in a puffier jacket. (The Halo Top contains 3.9 ounces (110 g) of down, while the Flight contains 4.7 ounces (133 g), not a big difference.)
When you hold a jacket with sewn-through construction up to a window, the lack of insulation at the seams and a narrow strip on either side is readily visible. How much does quilting affect jacket warmth? Read the next section to find out.
The obvious question is: does quilt size affect jacket loft and warmth? The answer is yes, and no. There are a number of factors at play here – the amount of down in the jacket, the quilt size, and packing density (how much the down is compressed). Looking at a seam closely, the seam itself has zero loft and a narrow strip on each side of it has little loft, so one would conclude that the seams create cold spots. The reality is the body only feels the average of all the factors involved. The variables mentioned have different effects on heat loss through conduction, convection, and radiation, but the body senses only general differences. You feel the relative difference in warmth from one jacket to another. Furthermore, wearing a windshirt or shell jacket over an insulated jacket integrates any differences due to jacket construction even more and adds an extra measure of warmth by holding heat inside. The bottom line is that jacket quilting has little effect on overall jacket warmth; the main factor affecting warmth is the amount of down in the jacket. Each jacket has its own level of perceived warmth, which is the average of all factors involved (including fit). And wearing a shell over a down jacket significantly increases warmth.
One thing that became obvious as we tested jackets for this article is that the women’s version of many (but not all) jackets is substantially different from the men’s version. At a minimum, the women’s version is sized and fitted for women. Responding to the market for “outdoor lifestyle fashion,” some manufacturers have added much more style to the women’s version in the form of a trimmer fit, less bulk (meaning less loft – women don’t want to look like a marshmallow!), and stylistic quilting. These embellishments definitely make women’s down jackets look good. But is there a cost in terms of performance? The trimmer fit increases warmth because there is less dead air space inside the jacket to warm up. With a heating pad inserted inside the men’s and women’s versions of the MontBell Ex Light jacket, we measured the surface temperature after one hour and found the men’s version to be significantly lower than the women’s version, meaning it insulates better. Richard Nisley’s “new paradigm for understanding garment warmth” would hold that down compression from the extra quilting in women’s jackets should not affect insulation warmth. So, the difference must be due to the overall increased heat loss through the jacket’s more numerous seams.
Features Add Weight
Ultralight backpackers want their gear simple, lightweight, and multi-purpose. For an insulated jacket, they would choose a down anorak with no pockets. Such a jacket provides the most warmth with the least weight. Other hikers would react: no pockets – no way! So they look for a jacket that provides a couple of pockets, again with the least weight. Now add a full-height front zipper (a must-have for many hikers) for convenience and extra ventilation, and it must be a light one, of course. As we add more features, jacket weight increases, but the emphasis is still on keeping the overall weight as light as possible. It’s entirely possible to add features while keeping jacket weight to a minimum, and some manufacturers do that elegantly. We sometimes refer to an “essential feature set” as the ideal compromise, which is a lightweight full-height front zipper, two unzippered hand pockets, and simple elastic binding on the pockets, cuffs, and hem. The essential feature set makes sense, but ask ten people to describe their perfect feature set and you will get ten different answers. Bottom line, features always add weight, so how many features do you want to add to an ultralight jacket?
All features add weight, but it can be minimized. For example, the Salomon Minim Down Sweater (left) has simple unzippered pockets, while the Westcomb Chilko Down Sweater (center) has zippered fleece lined pockets. One nice feature that is worth the weight is drop pockets (right) on the inside of the jacket.
Preview of Parts 2 and 3
Let’s get down to basics: a down jacket consists of down + fabric + features (zippers, reinforcements, cords, elastic, cordlocks, cuff tabs, etc.). The shell of a jacket made of the lightest fabrics (0.74 to 1 ounce per square yard) weighs about 2 to 4 ounces (57-113 g). A more durable fabric (1 to 1.4 ounces per square yard/34-47 g/m2) adds 1 to 2 ounces (28-57 g). Every jacket in this roundup has at least one feature – a front zipper – so add another ounce (2.5 g). The number of features, and thus weight, adds up. Now, let’s look at two approaches to creating an “ultralight” down jacket.
First, let’s look at a seriously lightweight (ultralight) down jacket. Start with the lightest shell fabric and think of it as an envelope that holds the down. A simple anorak (half-height zipper) with no pockets (like the basic Nunatak Skaha) is 50% down by weight. If an “essential feature set” is added (for example: a lightweight full-height zipper, simple hand pockets, and simple elastic cuffs and hem), there is still lots of room to add down and create a very light and very warm jacket or anorak. Jackets vary in the amount of down they contain and therefore vary in their loft and warmth. Their loft-to-weight ratio increases directly with the amount of down added, so the heavier minimally featured jackets in this group have more down in them, giving them the highest warmth-to-weight ratio. In summary, a true ultralight down jacket utilizes the lightest fabrics, has minimal and very lightweight features, and has a higher fill weight to jacket weight ratio. These jackets that best meet the needs of ultralight purists are evaluated in Part 2 of this State-of-the-Market Report.
The second group of jackets can be described as mainstream or multi-purpose “ultralight” down jackets. For some strange reason, “ultralight” jackets with lots of features sell the best, so they are abundant in the marketplace. They are designed to please as many people as possible, while keeping the overall weight impressively light (in the 11 to 14 ounce/312-397 gram range) to the average consumer. A jacket of this type will likely become your best friend. These versatile jackets are evaluated in Part 3 of this State-of-the-Market Report.
In order to compare apples to apples, this State-of-the-Market Report divides the jackets that meet our overall criteria into two groups – Seriously Lightweight Down Jackets and Multi-Purpose Three-Season Down Jackets – and evaluates each group separately. Within each group, we will rate the jackets according to appropriate evaluation criteria to identify the standouts. Since our main objective in this article is to identify the jackets most suitable for ultralight and lightweight outdoor pursuits, we will place extra emphasis in our ratings on criteria that emphasize overall light weight, minimal and lightweight features, and a high fill weight to jacket weight ratio. Standouts with these attributes will be identified for different situations and needs.
Acknowledgments
I would like to thank my wife Janet Reichl for her help in testing jackets for this article, as well as for her high quality photography and photo editing. In particular, we would like to thank Richard Nisley for his helpful suggestions and input to explain the perplexing issue of down density and garment warmth.
