FILL POWER: Fill power can tell you a lot about your comforter. On highest quality down comforters, you will typically see fill power listed (or how fluffy the comforter is). It is the measure for the amount of space one ounce of down takes up. The higher the fill power, the better the insulating ability and loft a down comforter will have. Fill power provides a good measure of warmth and quality. Why is fill power information important? A higher number on the fill power (typically a range of 600-800) means the comforter will be fluffier, warmer and last longer. Even though higher fill power costs more, in the long run it is worth having.

THREAD COUNT: Thread count represents the number of threads per square inch of fabric. Select down comforters will have a quality fabric with a high thread count. The higher thread count provides softness, durability and will keep the fill from getting out and impurities from getting in. It also means a tighter weave for a softer and silkier feel to the fabric.

Use and Care
Down comforters can't be tossed into your washing machine at home for two reasons. Home washing machines are too small, and the agitator in the center will do just that agitate it, which causes stress on the comforter. Take it to a Laundromat with a front load washer, or have it professionally cleaned.

Avoid harsh detergents and excessive heat because they will cause the down to become brittle and dry.

Completely dry the comforter for several hours so it does not stay damp and become moldy. Check it carefully for any wet spots or clumps. Put a tennis ball in the dryer to help keep your comforter fluffy. As mentioned, this will always be better achieved in a large size machine, giving the comforter plenty of room to fluff and dry completely.
What if I have allergies?
Few people are actually allergic to down. For the most part, people are allergic to the dust, dirt and other allergens in the down. Look for allergy-free comforters that are cleaned with a process that eliminates the impurities from the down, making them hypoallergenic. It also helps your comforter stay lofty and fluffy since the down is not weighed down by dirt.

How to keep it fluff
It takes approximately 72 hours to achieve maximum loft. Once you take your new comforter out of the packaging, place it on your bed and watch it grow! To keep it fluff, fluff your comforter daily and air it outside a few times a year in non-humid weather for a few hours. Drape it horizontally rather than vertically or on a clothesline. You can also throw it into a dryer on low heat along with a couple of tennis balls to fluff it up nicely.