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Down jackets are perfect when you need to be kept warm and protected from the cold, but what goes into the perfect down jacket? SGS explains what makes a down jacket work to help stakeholders and consumers understand the perfect down jacket.

Down is made up of clusters of filaments growing and radiating from a central quill point, but without a quill shaft. The three-dimensional nature of the structure means it creates thousands of air pockets, called loft. These trap air, turning it into the perfect insulator for winter jackets. Down is also highly resilient with the ability to resist damage caused by compression. Practically, this means it can be repeatedly stuffed into a bag without losing its ability to keep the wearer warm.

The effectiveness of the down jacket is the sum of its constituent parts, and so an understanding of what makes it work will help manufacturers and consumers understand the perfect down jacket.

When designing or buying a jacket, consideration must be made for:

Filling power – measurement of a down product’s loft in relation to its insulating value. Higher filling power means greater insulation because more air has been trapped by a specific weight of down. Filling power is usually measured by calculating how many cubic inches an ounce of down will cover, e.g. a down rating of 500 means one ounce will cover 500 cubic inches.

Down products range between 300 and 900+ but most common down products rate between 400 and 500. High quality down-fill jackets normally have a filling power in excess of 550, with high performance jackets with superior warmth having a filling power of at least 900.

Weight – an important consideration when choosing any item of clothing, especially when carrying is a consideration, e.g. for backpackers. Filling power becomes important as, to provide the same warmth, a down jacket with 500 filling power needs to be bulkier and heavier than a jacket of 800 filling power. In reality, there is often a trade-off between filling power and weight, depending upon the jacket’s function.

Percentage of down – normally represented as 80/20, 90/10, etc. This symbolizes the split between down, known as the down cluster, and feathers. It can have a major effect upon the jacket’s insulating abilities. Jackets listed as 80/20 will have 80% down and 20% feather.

Since down is a better insulator, warmer products will tend to have higher percentages of down, but this will also make them more expensive. It means two products with the same filling power will not necessarily provide the same insulation – two jackets with 750 filling power will provide different warmth if one is 90/10 and the other 80/20. The former will be warmer.

Construction – down baffling method. The two main quilting methods for down jackets are:

  • Sewn-through baffle
  • Box baffle

Sewn-through baffle is the most common method. It requires stitching around each baffle’s edge that goes right through the garment – from outer to inner layer. It is easier to make and keeps the down securely in place but it does have one major disadvantage – the outer and inner layers are drawn together by the stitching and this reduces the loft amount, which causes loss of warmth.

Box baffle is more difficult to construct as each baffle maintains its own three-dimensional rectangle. This technique reduces pinching at the seams and so the maximum amount of loft is created.

Durable water repellent (DWR) treatment for down – provides some resistance to light moisture.

The chief downside of down is that it sticks together and loses loft when made wet. It then loses its insulating properties. Traditionally, the response has been to seal it inside a fabric membrane but this means losing the advantage of down’s natural breathability. DWR treatments are now being introduced to help the down resist light moisture but they still will not withstand submersion or a heavy downpour.

Synthetic insulation – can resist wet, will dry quickly and is often more moderately priced. This is becoming a common alternative and, with newly developed microfiber materials that closely mimic the look and feel of natural down, the gap between synthetic and natural is closing.

Shell and lining material – can have a profound effect on durability, weight, warmth, and water resistance. Outdoor jackets should have a breathable shell fabric that will allow perspiration. If neglected, moisture will become trapped inside the jacket and this will dampening the down.

Nylon and polyester are commonly used for outer layers because they are durable and can withstand harsh conditions. When purchasing, look for a jacket that doesn’t show evidence of feathers leaking through the shell fabric, lining, seams and/or stitching. Try to buy a down jacket with an extra layer laminated onto the fabric. This will increase the jacket's ability to prevent down and feather leakage.

There are many factors to consider when looking at down jackets and this is without looking at additional features like hoods, zippers, pockets, adjustable hems, etc. The function of the jacket must always be considered. For example, a zipper that has overlapping panels will reduce heat loss and would be better in exposed terrain.

The same approach should also be taken with pockets. Function is everything. Is the way the pocket is fastened appropriate for the function of the jacket? Will they keep hands warm? Will they store items securely?

Down jackets are often expensive items. Care must be taken when choosing a jacket in order to ensure they fulfil the function required of the coat. Understanding design, manufacture, loft, filling power, down percentage and weight, will make it much easier to find the perfect down jacket.

SGS Softlines Services

With a network of over 40 laboratories around the globe, SGS offers textile and clothing manufacturers a comprehensive range of physical, chemical and functional testing services for components, materials and finished products. SGS helps companies ensure quality, performance and compliance with international, industrial and regulatory standards worldwide. Learn more about SGS’s Softlines Services.

For more information, please contact:

Sammy Chu

Senior Technical Service Manager

Consumer and Retail - Softlines

SGS Hong Kong Limited

Tel: +852 2765 3695



About SGS

SGS is the world’s leading inspection, verification, testing and certification company. SGS is recognized as the global benchmark for quality and integrity. With more than 95,000 employees, SGS operates a network of over 2,400 offices and laboratories around the world.