One of the few disadvantages of having recently bought a lovely yellow/gold down jacket, and worn it absolutely everywhere, is that it does start to look grubby. Fortunately, contrary to what I had thought, down jackets are not all that difficult to wash. You just have to follow a few steps:
Firstly, washing it:
Obviously you can hand-wash the jacket, but a machine-wash is absolutely fine; use a gentle spin cycle on 30°C and, if possible, skip the spin cycle. A down-specific detergent is best – Nikwax make good technical and down cleaning products that are widely available in supermarkets and outdoor stores.
This is actually the more tricky bit, as the washing process will have caused the down to clump together, and you need to redistribute it in the course of drying, so that you don’t end up with cold patches. The best way to do this is to allow it to gently drip-dry for a while, and then put it in a tumble-dryer on a low setting, along with two or three tennis balls, or the rubber balls that come with some down detergents for this purpose.
This should gently fluff the down back up and redistribute it, although I found that it can take a few tries, and the first time I wore it there were very noticeable cold patches. Putting it back in the tumble-dryer for a bit longer sorted this, and now my jacket is as good as new, and almost as clean.
This technique works for all sorts of down products including sleeping bags, and the tumble-drying method can also be used on its own if the down has become clumped, unevenly distributed, or if feathers are starting to poke through the outer fabric.