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What is Goose Down? What is Fill Power?

Goose Down is used to fill down comforters, down pillows, and other articles of bedding and clothing. It is chosen for it's luxurious softness, superior resilience, loft and insulating properties, unmatched by modern synthetic fills.

Down is the soft under plumage (a layer of insulation underneath feathers) that geese, ducks and other waterfowl have to keep them warm and dry. Feathers have hard quills, down does not. A down "cluster" is soft and fluffy and will have many filaments growing in all directions. A down cluster looks like this:

image of a down cluster

Goose down and duck down are basically very similar. However, because geese are larger than ducks, the goose down clusters will be larger than duck down, resulting in better insulation for down comforters and fluffier filling for down pillows. Larger waterfowl = larger down clusters.

White vs. Gray Down

Goose down can vary in color, from white to dark gray depending on the age of the bird and the season in which the down was harvested. The color of goose down does not affect its ability to insulate - in other words, a dark gray 650 fill power goose down will be just as fluffy and insulate just as well as a white 650 fill power goose down (from birds of the same age or maturity). Aesthetically speaking, white goose down is generally more preferable to gray goose down since a gray down can show through a fine white down proof ticking, making the comforter appear "dingy".

Fill Power

Fill power or "loft" is how the quality and size of various goose down clusters are defined. The larger the down cluster, the higher the fill power rating. Fill power is the number of cubic inches one ounce of down will fill under specific laboratory testing conditions; for example:

Illustration of goose down fill power and loft

Fill Power and Warmth

Fill Power and Comforter Warmth: Generally speaking, the higher the fill power (quality of goose down), the better. A higher quality goose down will provide a wider "comfort range". Ounce for ounce, a higher quality down will keep you warmer when it is cold and cooler when it is warm, compared to a lower fill power. Our down comforter warmth levels.

Fill power can range from 300 cubic inches per ounce, to 800 cubic inches per ounce and above, for the highest quality goose down. We use only the finest quality white goose down in our down comforters & pillows, including a 675 fill power, an 850 fill power, & an especially mature and dense 800 fill power (our "Plumeria" white goose down) that, due to it's exceptional "cling", much like eiderdown, is considered to be the best white goose down in the world. More about our goose down and fill power specifications.

Density and Cling

Fill power is important, and it is what everyone focuses on as a measure of quality goose down because it is relatively easy to measure and quantify. But, "density" and "cling" are at least as important when evaluating the highest quality goose down.

Density is an attribute of mature goose down. A mature down cluster with a denser center will insulate better and be more "resilient" compared to an immature down cluster of the same size, or fill power.

image of immature and mature goose down clusters

Cling is also an attribute of mature goose down, also known as"sticky down". "Cling" is found when tiny hooks develop on the individual filaments of a down cluster. Cling is found in genuine eiderdown and very mature goose down. The Polish White Goose Down found in our Plumeria™ duvets and pillows is exemplary of the finest mature white goose down, with superior attributes of fill power, density and cling. Here is a picture that shows this "cling" in action!

an image illustrating the 'cling' of fine mature goose down, or "sticky down"

Oxygen & Turbidity

Cleanliness: Improperly cleaned goose down can have dander, dust mites and odor issues. Most people that experience a reaction to goose down are actually experiencing a reaction to the dander and dust mites in dirty down. There are a couple of important tests that help manufacturers assure that down is properly cleaned; Oxygen and Turbidity. The "Oxygen" number test measures the presence of organic material and the Turbidity test measures the amount of dust and other non-organic solids that may be present in goose down.

The lower the "Oxygen" number, the better, in a range from 1 to 30+. USA standards require the minimum oxygen number to be 20 or lower. The higher the "Turbidity number, the better, in a range from 20 to 1000. There is no minimum standard for Turbidity in the USA. All Plumeria Bay® goose down and eiderdown has minimum standards of 2 (or less) for Oxygen, and 900 to 1000 for Turbidity.

The Best Insulation, Naturally

Ounce for ounce, goose down is the finest lightweight insulator known, natural or synthetic. It's unique three dimensional structure creates thousands of tiny air pockets. These air pockets, trapped by the down fibers, provide the superior insulating ability that goose down is known for. Quality goose down is also extremely resilient - the ability to be compressed then spring back to it's original shape with all of those wonderfully warm air pockets. No other material is as resilient as a high quality large cluster down.

Goose down is also extremely breathable compared to other materials. It allows water vapor to pass through, wicking it away through the filaments while retaining the warmth in the air pockets.

The down bedding law label describes the content of material used to fill down comforters and pillows.

About Siberian Goose Down


“My grandmother... simply loves her Plumeria Bay pillows.”
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“ is a gross understatement to say that we love it.”
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