Buyers Guide to Insulated Clothing

Everyone knows that to keep warm you need to insulate yourself from the cold.

THE most effective insulator is air, more importantly – dry air.

The more dry air you can trap against your body the warmer you will feel. However, air that contains moisture from sweat or rain will not insulate anywhere near as effectively so the layers you wear with your insulated jacket are critical to how it will perform.

Photo: Rab

What is the difference between down and synthetic?

Put simply; down insulation offers the most warmth for weight (when dry), it is highly compressible and with proper care will maintain it’s shape and loft for many years. Synthetic insulation is predominantly made from polyester (many of which are now recycled), it is easier to care for and will retain most of its warmth when wet.

Down comes from the fluffy plumage under the bellies of ducks and geese used to keep eggs warm. Different from feathers, down is made of a cluster of filaments, these filaments trap air extremely efficiently and down from more mature birds will contain more filaments than a younger bird making them more efficient at trapping air. In garments this is called loft, the higher the loft the more insulation.

Synthetic fillings come in three types: sheet, blown or active/breathable. Sheet synthetic jackets use flat sheeted panels of insulation, are generally bulkier and heavier but offer good weather resistance and are very durable. If you are out a lot in cold, wet conditions then this is the garment for you! Blown synthetic jackets use clusters of polyester fibres to mimic the loft of down creating a jacket that looks like a puffy down garment. They require stitched baffles to keep the insulation in place and are therefore less weather resistant and less wind resistant than sheet synthetic jackets. Finally, Active or breathable synthetic fillings are structured and super fibrous offering the highest possible synthetic warmth to weight ratio. Some have a silicone treatment making them highly water resistant and smooth so they move well over other layers.

Why aren’t insulated jackets usually waterproof?

For a jacket to be waterproof all seams need to be taped. This is an expensive process, increases garment weight and any waterproof coating will reduce a garments ability to transfer sweat away from the body, so once you begin to expend any energy you are likely to overheat unless you are in an extremely cold environment. Of course, it doesn’t rain in an extreme cold environment, it snows so a snow proof insulated jacket can be far more practical and cost effective. In our generally warm wet climate here in the UK, the versatility of using an insulated jacket as part of a layering system means you can get the maximum use of all garments throughout the year. If you buy your clothing to allow for layers underneath/on top then you can happily use your insulated jacket under a waterproof of really grim days (or Scottish winter walk ins!) or simply as an outer layer on crisp cold dryer days.

There are specialist products on the market from Grangers and Nikwax you can use to add water resistance to your garment.

Can you get water resistant down?

Yes. Some companies such as Rab apply a Nikwax water repellent “hydrophobic” treatment to their down. This treatment significantly improves the performance of the down by preventing the clusters from absorbing moisture and helping it to retain its loft. In the event that the down does become waterlogged, the treatment significantly decreases the time it takes the down to dry and its loft to recover. However, it’s worth noting that hydrophobic treatment means that a down jacket will perform better in wet conditions, but it’s not intended to make a garment waterproof. If you’re looking for a down jacket that is also waterproof you’ll want something that combines insulation with a waterproof material and taped seams.

Just in case you are wondering – yes, down is naturally water repellent (Ducklings are covered in it for good reason!) However, when it comes off the bird, down is quite smelly and will rot quickly if not properly treated. This process effectively strips the down of its water repellency – hence some companies choose to add a man-made chemical solution. When used properly, a standard down filled garment will work just as well.

How do the baffles work?

Baffles are sewn into a jacket to keep the insulation in place. Most common are baffles that are sewn through creating little “pillows” of insulation. These are used in lighter weight garments and  ideal for activities as where the stich lines are there is little insulation. Box wall construction is generally used on jackets that have more loft and are designed for colder environments as baffles are stitched to ensure there is a continual depth of insulation.

How do I know how warm a jacket will be?

It is important to understand that a jacket will not generate warmth by itself – it is your body that creates heat either through movement/exertion or by eating and drinking. The jacket will then trap the warm air to keep you insulated.

When it comes to a down garment you can use the amount and quality of the down in the garment as a guideline. As we mentioned above, the more loft: the more insulation and loft is measured and described as fill power.  Fill power describes the amount of space 1 oz of down will fill. So for example; higher quality down will have more filaments and fill a bigger area therefore 1oz of high quality down may fill 800 cubic inches of space and that is known as 800 fill power down. Check the weight of down alongside the fill power too as the more down there is physically in a garment the better it will insulate, it may just be a little heavier and less compressible.

For synthetic garments the weight of the insulation is measured in grams per square metre to help understand how much insulation is inside the jacket and therefore how warm the jacket may keep you. The higher the weight; the warmer. Blown synthetic jackets may quote a slightly different “Total Fill” measurement due to the way they mimic down.

Finally, how a jacket fits is critical to how warm it will keep you out on the hill. A jacket that is too big will allow all that lovely warm air your body has worked hard to warm up to leak out of the base or get squeezed out of the back if there is too much room. Conversely, insulation cannot work efficiently if it is crushed, so a jacket that is too small will not work. If you are planning on wearing layers underneath, it is worth taking this into account when trying on before you buy. Different manufacturers pattern their garments differently so make sure you buy the right one for your shape – not necessarily the colour you like best!

Why do I need to think about how the hood fits?

Hoods are a vital part of how your insulated jacket will keep you toasty warm whether it is on a belay stance or sitting around a campfire on a cold starry night. An astonishing amount of heat is lost through your head and a well-fitting hood will ensure the majority is kept within your jacket. If you are using your jacket for climbing then be sure to try it with a helmet so that you can maintain vision and cinch down to stop any pesky spindrift getting in.

Why should I not buy a cheap down jacket?

If you have a strong constitution, then search online for “live plucking”. It is even more horrific than it sounds and there is no reason why an animal should suffer so that you can save a bit of money. Look for products containing down that is RDS approved or the Mountain Equipment down codex allowing you to trace the down in your garment back to source to ensure animal welfare has been taken into consideration during production.

Can I buy a recycled down garment?

Yes! All of our key brands offer a variety of insulated garments that are made from either recycled down or recycled synthetic insulation and some even have outer fabrics made from recycled nylons and polyesters. Just ask our staff or look in the product descriptions if you are buying online.

How do I wash an insulated jacket?

All garments will last longer if they are washed and maintained on a regular basis. Down jackets in particular will lose their loft over time with sweat contaminating the down clusters but a wash and tumble dry can make all the difference.

Synthetic jackets are simple just follow the washing instructions on the label inside the jacket using Nickwax Tech Wash or similar. Almost all of them can go in the machine.

Down jackets require a little more care and you can download our down care guide here. The key is drying as any down garment will dry on the outside a loooooong time before the down inside is dry. Popping a tennis ball in the dryer can help and you’ll know it’s done when you can’t feel any clumps.

Alternatively, Rab & Mountain Equipment offer pre-paid down washing services on their websites and Scottish Mountain Gear also offer a down cleaning service for any brand.

Top Tips:

Wearing cotton layers underneath your insulated jacket may well lock in sweat making you feel damp and therefore cold. They definitely work best with wicking layers underneath.

Check what the outer fabric is made of as some insulated jackets are designed to allow air through so they can work more efficiently in a layering system. If you are wanting an “outer” jacket then look for one with a windproof outer fabric.

If pack size is important then down garments will always pack smaller than a synthetic jacket of the same weight.

Click the image to listen to our lighthearted podcast about insulated clothing - Snug As a Bug!

Want to know more about ethical down and how it keeps us warm? Take a list to Episode 41 of Outdoor Gear Chat when Cathy and Wayne talk with Dr Down…..