I know there have been threads on this topic (feel free to point me in the right direction).
1) What product do you use to clean your down sleeping bag? What was the outcome?
2) Hand wash or front loader?
3) What do you treat your bag with to make it water resistant? What was the outcome?
I'm getting ready to wash and treat several down bags and since they're all WM bags I want to do it right.

1 I use Nikwax Downwash. The bag gets clean.
2. Hand wash in big tub and spin slow in the washing machine. Then tumble dryer.
3. I dont treat it. If I need weather resistance i use a bivy.

The tricky part is the dryer. I use a large dryer on low heat with some tennis balls thrown in. A winter bag takes VERY long time to dry. I had mine in for about 6 hours. If it is not in there long enough the down will clump together and the bag will loose some insulation.
Be very careful when handling a wet down bag. Baffle and stitching are delicate and more so if it´s a UL bag.

Have washed my WM Ultralite in our front-loader, IIRC using Nikwax down cleaner. IMO any proven down soap will do.

Turned it inside-out, as the liner doesn't seem to be DWR treated and absorbs water more readily. Used gentle cycle (because I R smurrt) and additional rinse cycles afterwards to maximize soap removal. Dried it turned right-side out because the shell is tougher and to renew the DWR finish. The dryer heat accomplishes this.

It seems to take awhile--days--for the down to completely dry and declump. I like to do this in summer so I can put the bag (or whatever) out in the hot sun to help drying and minimize the potential wear from the dryer.

Have never bothered with DWR sprays, but if after washing and running through a dryer water doesn't bead on the shell, it's probably worth a shot. The Gore spray seems to work on rainshells, so probably works on bags. Just don't soak the fill.

I don't do this often but have never regretted it, as the bag is always loftier after washing, not to mention smelling better.

Cheers,

I followed exactly the instructions on the Western Mountaineering website for product care, including using the Revivex down soap and DWR spray that they recommend.

My DIL has an extra large capacity front-loading washer and dryer, both with extra-delicate cycles, so I used those. With any machine, be sure to run a cycle or two with only water to get all the detergent out before you start. I cleaned the slot where the detergent is put in and then ran two full cycles to be sure (I could still see some suds at the end of the first cycle).

It took about 9 hours including the water-only cycles to remove detergent at the start, so if you go to the laundromat, take a big book, like War and Peace, plus tons of quarters. Be sure you find a machine with a delicate cycle, check the inside for snags and do extra rinses.

The WM website also describes how to hand wash in the bathtub, which is more work but at least saves hours of boredom at the laundromat!

You can also send it to an outfit that specializes in washing down sleeping bags, such as Rainy Pass in Seattle.

My sleeping bag ended up loftier than it was when I bought it!