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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:

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.

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 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 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.

Fill power is important, and it is what everyone focuses on as a measure of quality goose down because it is relative 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. "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

Cleanliness & "Hypoallergenic" goose down: Improperly cleaned goose down can have dander and dust mites. Very dirty goose down can have 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.

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




“The featherbed is fabulous.”
“My grandmother... simply loves her Plumeria Bay pillows.”
“ is a gross understatement to say that we love it.”
“It doesn't get better than this”
“In a heartbeat, I would and will order again !!!!”
“I'm not usually one to gush over a product, but...”
“Expensive? Yes. Worth it? Absolutely.”
“Great customer service and an amazing product. We will be return customers.”
“The comforter is absolutely perfect in every way!”
“....a very high-quality product that lives up to its description...”
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