I have a marmot sawtooth with the membrain waterproof fabric to protect the down. I followed the instructions for my particular bag. They did specify front loading washing machines only. Supposedly the other types agitator could "burn" a hole in the bag from friction. I used nikwax sport wash made for waterproof fabrics and tumble dry low for two cycles. Everything came out a-ok. (I only wash mine every 3-5 uses)
•Use any mild, non-detergent soap or non-bleach stain treater
•Shake the down away from the spot you are treating and, using a clean terry cloth saturated with soap and water, gently scrub the stain until it fades
•Wipe the area with a clean, damp cloth to clear away the soap residue
•Make sure the item is completely dry before storing it
Machine Washing
•Use the largest front-loading commercial washer you can find. Do not use top-loading washers with agitators; they will damage your garment or sleeping bag
•Use down soap such as Nikwax Down Wash or ReviveX Down Cleaner Concentrate. These specially formulated cleaners will help to preserve the natural oils in the down while still getting your item clean and restoring its loft. In a pinch, you can use mild, non-detergent soap diluted with water. Never use bleach, bleach-alternatives or fabric softener.
•Apply soap directly to heavily soiled or stained areas and soak for up to one hour
•Be sure to turn garments and sleeping bags inside out prior to washing. Water will escape through the lining material more easily than it will through the water resistant or waterproof shell material during the spin cycle
•Use the normal, cold water cycle, with a cold water rinse
•Run through a complete second cycle without soap. This will ensure that the soap residue is completely rinsed out
•Carefully wring as much water out of the bag as possible before attempting to lift it. Although we use a durable tricot baffling material, the down in your garment or sleeping bag will be heavy when wet, making it easier to tear the baffles inside the item if it is not handled carefully
Hand Washing
•Fill a large wash basin or bathtub with cold water
•Use down soap such as Nikwax Down Wash or ReviveX Down Cleaner Concentrate. Never use bleach, bleach-alternatives or fabric softener
•Apply soap directly to heavily soiled or stained areas and soak for up to one hour
•Gently knead the item from one end to the other making sure that all of the down is soaked and there are no air pockets
•Rinse several times with cold water until the water runs clear and all of the soap is rinsed out of the bag
•Carefully wring as much water out of the bag as possible before attempting to lift it
Drying
Drying can easily be the most time intensive step in cleaning down items. This is especially true with larger down garments, sleeping bags, and comforters where the drying process can typically take several hours. It is important to dry your down products properly, and not to cut corners. For maximum effectiveness, do not flat or hang dry down items.
•Move your product from washer to the dryer. Always carefully carry down products from the underside while they are saturated with water
•Use the largest front-loading commercial dryer you can find, set to medium heat
•During the drying process, it is important to periodically go through the item and manually break up the clumps of down that have formed during the wash process
•Make sure your items are completely dry before storing them
DWR Replenishment
The Durable Water Repellant (DWR) finish that is used on all of our technical fabrics will need to be replenished from time to time. If you notice that water is no longer beading up on the surface of your garment or sleeping bag, wash the item and then dry it on medium heat for 30-45 minutes to re-activate the DWR finish. If this doesn’t work, you will need to apply a DWR replenishing treatment such as Nikwax TX.Direct Spray-On or ReviveX Spray-On Water Repellant. Follow the DWR manufacturers’ directions.
Storage
Store your down bags uncompressed, either lightly stuffed in a large, breathable bag or hung in a dry location. All Feathered Friends sleeping bags come with a large, cotton storage sack specifically made for long term storage. To discourage the growth of mildew, make sure your items are completely dry before storing them.
Shifting the Down Fill in Your Sleeping Bag
Some sleeping bags are constructed with continuous baffles—fabric tubes—that hold the down in place and wrap completely around the bag. This design allows you to shift the down to the top or bottom of your sleeping bag, effectively raising or lowering its temperature rating, according to the season, changing conditions and your personal preferences. For example: if you are using a thick, down insulated sleeping pad, you may want to shift all of the down to the top of the bag, where it can loft fully, to extend the comfort rating. Alternatively, in warm summer temperatures, you may choose to shift some of the down to the bottom of the bag so you don’t overheat during the night.
•Begin by unzipping your bag completely and laying it out flat
•Next, hold the edge of the bag and give it a few firm shakes. The down will slide in the baffles and end up on side of the bag opposite you
•To return the bag to its normal configuration, simply reverse the process
•The inevitable, uneven shifting of the fill that occurs during normal use can also be corrected with the above method
There is/was a good write-up on the Western Mountaineering web page on this subject. You need to use a washing machine with no aggitator (front loader) so you do not tear the fabric, special soap, support it completely when moving to the dryer so as not to tear any baffles (they get really heavy when wet), and dry it in a big tumbling dryer with a few clean tennis balls (or similar) to break up clumps - low temp I think. This means an afternoon at a laundramat. I've only done it once and it was a number of years ago.
Edit: I see someone added a post with....slightly more detail...while I was posting.