In reply to Dave Rudkin:
It's fine to do at home but it's a laborious process. The steps I followed are
1. Put the washing machine on a cycle and throughly clean washing machine to remove any left over debris or washing powder which when dried to the down clusters can cause a loss of loft.
2. Use a specialist down cleaning product from nikwax and use a delicate wash with a extra rinse cycle and extra water in the washing cycle as the down will absorb alot of water. Some people like to add 400rpm or low rpm spin at the end this cycle but I don't cause it can damage the bag.
3. Line dry letting all the water drain out in the machine first if possible. Once on the line break up the down do help it do dry. Leave the bag to drip for 2 hours or so.
4. This is when I do my low rpm spin and the bag is lighter and is less prone to damage this should avoid baffles ripping. At this stage break up the down once more.
5. Line dry until damp breaking up the down every hour.
6. By this point it'll be late in the day and the bag will be lighter so time to go in the tumble dryer for a while with a few tennis balls or the special things for breaking up down. This is very noisy and annoying.
7. Take it out break up the down between your fingers again. Return to dryer if needed stopping every hour to break up the down. Repeat this step until it is dry.
8. Air the bag for a couple of days to absolutely make sure it is dry before storage if it isn't it go mouldy or lose loft.
9. Put it in the dryer with tennis balls fluff the down up.
10. Storage is key make sure the stuff sack or storage bag is clean too.
As you can see this is a long and annoying process and my 3 season bag took 2 days to dry out properly and even then I tumble dried it once it was dry to ensure that it wasn't damp in the stuff sack. I would recommend leaving it to air out properly aswell. The online guides make it seem so much easier and hassle free. I believe RAB do a washing service for their kit, and I vaguely think alpkit do aswell but they may not. Sports repair shops tend to do a cleaning service aswell look around online.
Post edited at 16:30