Beginner's Guide to Down & Down Jackets
When the drop in temperature signals the approach of winter, Gear-Zone sees the arrival of our new range of insulated down jackets. Down jackets are as much of a minefield of technical terms as most other outdoor clothing and equipment, so here's a handy guide which covers all the basics of down and down-filled clothing, giving you a better idea of what all the specifications and figures really mean. Here we're concerned spefically with down-filled clothing - however the basic principles apply to down sleeping bags as well.
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What is Down?
Down is possibly nature's greatest insulation, and the one of the easiest to adapt to human use. Down is basically a very lightweight and 'feathery' feather, which when combined with more down, traps a very large amount of air. This air is then heated by the body to provide insulation.
Most fowl produce down under and between their outer and flight feathers to give them insulation; we can see how effective down is as insulation by marvelling that geese and ducks can quite happily survive in extremely cold weather - which would kill all but the most specialised mammals.
Birds of course, are perfectly adapted to the environments they live in, so the outer feathers, oils and fat/blood circulation systems all help, but down is a primary weapon in their insulation layer.
Humans and especially outdoor folk admire down for four key reasons:
- It is very lightweight
- It is very warm
- It is very breathable
- It is very compressible (and recovers well from compression)
In combination, these properties create the ideal insulation; one that has a peerless warmth to weight ratio, that will still pack small enough to be carried when not in use, and won't make you feel too sweaty when exerting yourself. It will also last years if treated correctly.
Most people will be familiar with down from duvets and pillows, but maybe not necessarily with how we get hold of it. We'd like to skim over this point, but we feel it's necessary.
Unfortunately, down is primarily a by-product of the poultry industry, and so far as we are aware there's no vegan down. During the process, the birds are plucked and the feather/down mix is taken away for further processing and refinement, where it will be cleaned, and depending on the end use and quality ordered, the feathers will be removed, much like distilling oil into higher grades.
Many of our manufacturers, like Rab, now insist on codes of practice for the fair treatment and humane collection of down from their suppliers, but when buying 'high-street' or very cheap down jackets it might be worth bearing in mind that like leather, meat and eggs; down is an animal product.
Of course there are synthetic alternatives available such as the fantastic Primaloft as used in The North Face Redpoint Jacket, although because nature's had millions of years to perfect down and we're generally playing catch-up, most people still feel down is the choice for extreme cold.
Down Specifications Explained
Goose vs Duck
The two primary kinds of down used in the trade are taken from either geese or ducks (of varying species). Eider down is a famous example of a duck down. As a rule of thumb, goose down will generally provide larger clusters, giving a greater loft/fill power, and allowing for a better ratio of down to feather. This means goose down will usually perform better than duck down - eider down is an exception to this rule - and is the choice of filling for high-altitude, or extremely cold conditions clothing. On the plus side, duck down will usually be cheaper, which makes it a good choice for budgets, or use in more temperate winter conditions like the UK.
European vs Chinese
Down is primarily sourced from either Europe or China. European down is regarded as the better as the birds are usually allowed to mature longer, and is therefore, a higher quality. This does of course make it the more expensive option.
Down and Feathers
At the start of the down manufacturing process down and feathers are mixed together. Down is the small, soft and fluffy feather which lives close to the bird's skin (it looks much like a powdery snowflake). Feathers are exactly what you'd expect - the longer, thicker feathers for flight, and protection.
For best insulation, the outdoor industry really only wants the down portion of the mixture...feathers do not insulate nearly so well, pack so small or recover after compression. The quills can also be uncomfortable and damage fabrics, as anyone who's slept on a cheap down pillow will attest to.
Once the processing is complete you'll have a mixture which is usually expressed in a ratio. (See below for more info)
Simply the measurement of the mix of down and feathers in the fill; the higher left-hand number, the better the insulation. Of course the price also rises accordingly as it costs more to refine the down.
Just to confuse matters, there are differing US & EN standards used to measure the down/feather ratio. US figures are exact (US 90/10 is 90% of down), whereas EN figures essentially over-estimate (EN 90/10 is 80.95% of down). Handily enough we're pretty sure most key outdoor brands use the literal, US version.
Commonly figures start at a 50/50 mix (50% down/50% feather), and rise to 95/5 (95% down/5% feather)
- 50/50 is often used on cheaper jackets and fashionwear where conditions are expected to be cool, but not extremely cold, or style/cost is more important than actual performance. Most outdoor jackets will have a higher ratio than this as simply put; half the fill isn't really doing anything!
- 80/20 is usually warm enough for even the worst commonly encountered UK cold.
- 90/10 provides an amazing amount of warmth for its weight and can be found in top-end insulation pieces for extreme conditions. 95/5 is occasionally used in the very top-end products for high-altitude, or Arctic/Antarctic conditions, but it's rare to see on the general market because it's really hard to get this ratio. It's also really, really expensive!
- 100/0 is never found, as down cannot be sorted that effectively.
The Fill Power is most basically the size of the down clusters and ability of the down to loft. The higher the number, the better quality the down is, and the warmer the jacket will be.
Goose down will usually have a higher fill power, with the average being between US 650-850, whilst duck down averages US 500-700. Fill Power is measured in a loft test, which looks much like the above image.
Annoyingly for the outdoor trade, there are also two loft tests standards; the US and EN. Each treats the down differently before testing, and the figures vary, with EN figures generally appearing lower. Therefore a US 700 fill power is not the same as an EN 700, but is probably closer to EN 550. Most outdoor brands now use the US fill power test in an attempt to self-standardise the industry, but it is worth looking out for.
Usually expressed in grams, this is literally the weight of down in the jacket/panel. Generally the more down, the warmer the jacket, but should be used in combination with the fill power & feather ratio figures to give a better idea of the overall performance. For example: 240g of US 700 90/10 will be much warmer than 240g of US 550 70/30.
Down's only real weakness as an insulation piece, especially in typical UK conditions, is that it really, really doesn't like getting wet. When down becomes saturated it clumps together and loses the majority of its ability to insulate. Once clumped it is unlikely to function until it can be dried, and probably have the clumps broken up (a tennis ball and a gentle tumble dryer are ideal).
To this end, care should be taken with down to make sure that if you intend to wear it in the rain, you either by a waterproof down jacket (rare), or simply take a shell to wear over the top. The other alternative is to buy a synthetic-filled jacket, which retain a much better insulation value when soaked.
This could be a guide to itself really, but at a most basic level jackets designed for UK or European-esque temperate winters and winter sports will usually tend to have either a 'stitch-through' or 'Box Wall' construction.
Stitch-through is arguably a slightly less efficient option in terms of retaining extreme warmth, but it does allow for less fabric to be used to keep weight, pack-size and cost down. It can cause cold spots, although most of our suppliers will minimise this in various ways. Some examples of a stitch-through jacket include the Rab Neutrino and the Rab Women's Neutrino Vest.
The more technical method of constructing a jacket basically consists of making Box, or Trapezoid baffles (compartments) for the down to live in, which helps to keep it where it's needed and eliminates cold. This makes the jacket heavier and more expensive, but also warmer and is ideal for really cold conditions, like high altitudes or Arctic conditions.
There are many variations on the above methods but the pictured ones are the 'usual suspects'.
Sometimes different combinations of baffles and/or fill are used on different areas of the jacket, so you may have different fill over the arms, shoulders and torso. This helps to save weight and keep insulation distribution where it's need most. For a beginner's guide it's acceptable to say that, if you're using the jacket for intended purpose, the construction method will be the most appropriate.
Most down jackets are constructed from lightweight windproof fabrics, such as Pertex.
Each fabric will have different strengths and weights so we'll not go into that, suffice to say that jackets for expeditions and tough use like the Rab Summit Jacket will generally have heavier, more durable fabrics; whilst jackets designed for fast & light activities or those intended to be highly packable such as the Rab Women's Infinity Jacket will have lighter fabrics.
Of course all-round jackets like the The North Face Nuptse II have a fabric which is still lighter than most waterproofs, and also more breathable.
All down jackets tend to be windproof, downproof (to stop leakage) and have water-repellent DWR treatments to shed snow and light rain. This ensures that the air trapped by the down does not get blown away, and helps the jacket to perform at an optimum.
Waterproof Down Jackets
There are relatively few fully waterproof down jackets on the market, although examples include the Rab Microlight Event and The North Face McMurdo Parka.
The reasoning behind this is that down jackets are designed for cold conditions where precipitation will fall as snow, if it falls at all. Plus waterproof fabrics are never as breathable as non-waterproof and therefore they can get very, very hot, making you sweat, and having to open the jacket to vent. This then causes fast cool down and the process will be repeated all day.
Non-waterproof down jackets are always more breathable than a waterproof shell, so they can quite happily be layered under a shell for versatility and protection if needs be.
Care & Tips
- Never store down in a compressed state
- If you've finished with it for the trip/season, hang it up. Down will lose its loft if compressed for a long time, effectively reducing its warmth.
- Never pull down through the seams
- Sometimes you'll see down/feather protruding through a seam...resist the urge to pull it out! Down clumps because it's quite spiky (under a microscope), pulling will often only help to get another bit stuck in the seam. If possible try and pull it back into the jacket.
- Clean your down jacket carefully
- Down jackets will need cleaning every once in a while, however they can be tricky, read our down cleaning guide for more info.
View our range of men's down jackets and women's down jackets