No other insulator exists that is as effective as good quality down.

Insulation: It is not the down itself that actually does the insulating, it is the tiny air pockets trapped by the down fibres. The smaller and more numerous the air pockets, the more efficient is the insulation, as convection currents that carry heat away are eliminated.

Resiliency: Resiliency is the ability to be compressed and then spring back to the original volume. No other material regains its "Loft" like down. Obviously, if a material does not spring back to its original volume, it loses a considerable portion of its insulating power. Quite simply, thickness is directly related to insulating power.

Why Down

Breathability: Down is superior to other materials in its ability to "breathe". It actually allows water vapour to pass through it, without letting warmth escape. This means that the sleeper will not get clammy, because the down has "wicked" away the moisture that would be trapped by other materials. Considering that a person can perspire up to a litre (1/4 gallon) in a night, you can see why a down duvet can be cooler in the summer than other bedcoverings.

Longevity: With proper care, Down will outlast any other insulating material. St Genève have recovered quilts up to a hundred years old, and the filling was still in good condition.

Lightness: To achieve the same insulating power, far less down by weight is required than any other material. Therefore, an individual will enjoy a much more restful sleep, since she is not weighed down and restricted in her movements.

Why Down
65 year old Goose Down

all the things that down does; insulation, longevity, breathability, and lightness, are far more pronounced with high quality, large cluster mature downs.

Down Quality

What makes one down better than another? If it is a batch of large mature clusters, it will be warmer in winter, cooler in summer, and last decades longer. High quality down fills a larger space and has more insulating power than the same weight of a lower quality. Small down clusters have poor filling power and tend to collapse after two or three years, because the filaments are small and fragile. There are different reasons for variance in down cluster size.

Down is an incredible insulator

In general, goose down is superior to duck down simply because it usually comes from a larger bird. But more important than the kind of bird, it is the bird's size and maturity that determines the quality of its down. So in fact, a high quality duck down is better than a low quality goose down.

There are big differences even in one type of down. For example, mature White Goose Down will look like the large down plumule in the image (top right), in actual size. It has an extraordinarily high warmth to weight ratio. A duvet filled with this down will be very light and warm, and will last for decades.

On the other hand, an immature White Goose Down will look like the small down plumule in the image (bottom right) in actual size. It will not fill a duvet well. Even if there is a lot more of this down by weight, it won't be as warm.

Mature and
immature down
Mature and immature down

Mature down traps more air, puffs up more, and breathes better than lower quality immature downs. Since it takes less weight of a high quality down to fill a duvet, the best duvets are also the lightest and puffiest.

An immature bird will only produce immature down: a low quality down that won't insulate and won't last. A mature bird will produce down in various stages of development, because a bird is constantly growing new down and feathers. So from a single bird, there will be very large, mature plumules, as well as medium, and small immature plumules.

Down Quality Sorter

When this type of down is processed in a "wind tunnel separator" (diagram shown above), the large feathers fall out first because they are heavy, then medium feathers, then small feathers, then large down plumules, and finally the smallest plumules get collected at the very end of the tunnel. These small plumules are of much less value and are sold for mass merchant, low quality down bedding. The large plumules have the greatest value, and are used to fill high quality down bedding.

There are four aspects to consider in rating the quality of down. They are all very important in determining the insulating power of a given quality, and the size of the cluster. These aspects include: a loft test; the density, the cling, and cleanliness of down. All these are a reflection of the overall quality of down.

Loft or Fill Power

Loft is the number of cubic inches one ounce of down will fill under specific conditions of temperature, humidity, and load. (This can be artificially increased by chemical treatment and steam, but this won't last very long.) Essentially, the larger the bird, the larger the down clusters, and therefore the higher the loft.

The illustration below shows 1 oz each of different quality downs in tubes. They vary from 300 cubic inches per oz; which is a typical mass merchant bargain white goose down, up to 1,000 cubic inches per oz, which St Genève top quality downs achieve.

Loft Power

A loft test is done in a plexiglass cylinder of a standard size, under exacting conditions of specific temperature and humidity, with a sample of precisely one ounce of down. There is a disc of a specific weight that sits on top of the sample to simulate the load that the covering fabric exerts in a finished item.


The density of down describes how dense the fibres of the down are in its centre. The down actually develops microfilaments on the strands of the down cluster. The more of these tiny fibres there are, the smaller the air pockets that will be trapped, and the better the down will insulate. This is affected more by the age of the bird. High density is only found in very mature downs. Note that the loft of these two downs will be the same, but the down in image 'B' will insulate better than the down in image 'A'. >/

Density 1
Density 2
"A" is a large down cluster that has not yet developed high density.
"B" is from a well matured bird, and has developed a high level of density.


Cling is found when tiny hooks develop on the filaments of a down cluster. These hooks will catch other down clusters to make a more even layer of insulation, and as large pockets of air are filled in and eliminated, the insulating power goes up.

A down with a lot of cling will also stay in place on top of the sleeper, rather than shifting to the lowest parts of a duvets chamber. Cling is either species specific, as in genuine Eiderdown, or it is found only in very mature downs. In general, as the size of the bird increases, so does the loft of the down. As the age or maturity increases, so does the density and cling. This is why the best down comes from much older birds. They have grown up to be large, and then with further aging, have developed completely mature down. It is expensive to maintain birds well into maturity. Since it is expensive to process down with high clinging ability, the very best down is very expensive, yet glorious!


Quality Assurance


The Down Association of Canada is a non profit organization devoted to maintaining quality standards for down and feather products. Members are obliged to adhere to strict standards under government labeling and advertising regulations. Members products that meet these standards are entitled to carry this hang tag.

The principals of St Genève have been closely involved with the Down Association of Canada since its inception, and were instrumental in bringing the hang tag program into effect.


All St Genève down is cleaned according to the ZURGUARD standard. St Genève down is so clean that they confidently guarantee their down products to be hypoallergenic or the item can be returned after a period of three months from the date of purchase. (The return period is for three months as they have no control over the ongoing household environment.)


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