There are a lot of ways out there to wash wool, but it's not something you have to overthink. it doesn't need to be hard.
The first thing you have to think about it's where you are going to be washing the fleece, are you on town sewer, or do you have a septic tank? If it's just one fleece then you're probably fine to wash it in the sink at home. However, if this isn't a one-time thing then you should probably wash them outside so you ruin your septic with the lanolin.you can either get some sturdy tubs that will hold water, or I've seen people go to the dump and find a sink and make a stand for it or If you don't mind spending some money you can even go and buy a laundry sink and set it up outside. Once you have your sink (or tubs) setup, just run a hose from the house to the sink. You will need some mesh laundry bags. If you don't have any you can pick these up pretty easily at any store, like Walmart or Dollar General for example, and finally, most importantly you'll need soap. There are lots of wool soaps out there, but I think regular original Dawn works the best and it's not only the cheap, but the easiest to come by and it isn’t harsh on your wool.
When starting don't forget to turn up your hot water as hot as you can, I like my water around 140 degrees. If you have little ones make sure you don't let them use the hot water while it is turned up, you don't want them to get burned!
take out your fleece and lay it on an old sheet down to skirt your fiber and get it all prepared. (see the previous post how to do this). Once the fleece is nice and open and picked apart carefully fill the laundry bags evenly in the bag until it's full.
You will want your laundry bags full but not so full of water can't get through. Fill up the sink/tub with the hottest water you cant get (approximately 140 degrees), I don't get super technical, I just want it hot enough you don't want to put your hands in it. Depending on the soap you are using you can add the soap, the key is to add the soap after you have filled the sink/tub. If you're using Dawn dish detergent I would use about ⅛ of a cup ¼ of a cup. Dawn is super sudsy so you need to find a happy medium that works for you. You don't want it so soapy it will never rinse out. If you're using a laundry sink I can usually fit approximately 3 bags in the sink however, if you're using a tub or smaller sink then just put one bag. You want the fiber to be able to move around freely in the sink if they're too squashed they won't come clean. The first time doing this you might have to do some trial and error as the amount of fiber in the bags. Place the fiber in the soapy water and pushed them underwater (I use a stick) so they're submerged, that's it,I told you it wasn't that hard! You don't need to move them, just let them sit there. If you play with them too much you could felt the wool.
Let the fiber sit for 15-20 minutes, if it's cold out and the water is going to cool off quick then shorten the time, if it's hot out then you don't have to rush. When time is up take the bags out of the sink, hold them up to drain as well as you can. If you have a top loader that has a spin cycle you can spin the water out, ( not everybody wants to put dirty wool in their washer) but draining them by letting them drip is fine. Repeat the process at least one more time.
Depending on the fiber type you might have to repeat the process again. Remember, Fine wool tends to be more greasy than other wools. The heavily greased fleeces will probably need a third wash, be sure the water stays hot enough to melt the grease. One indicator that I use is, if the wool is soapy and you can hear the soap bubbles in the fiber then the wool is probably ready to be rinsed, I notice this more in finer fleeces, this isn't a guarantee just an indicator.
Once your fiber is washed you will need to rinse it. This is super easy, you do the same thing you have been doing except you leave the soap out. I usually rinse at least twice maybe a third time, especially if the fiber was super dirty. You'll know it's done when your rinse water is clear and you can see the bottom.
Drain out your bag(s) of fiber or spin them out if you can and lay them out to dry. Once it's dry you can process your wool anyway you like!
Something to remember when washing is ... fiber can always go from cold to hot, but don't ever go from hot to cold! That will be a felted mess! Hot opens the scales in the fiber, cold closes them. I really hope this will help someone on their fiber journey, this is supposed to be fun not a drag. Give it a try, I have some customers that do the initial wash then send the fiber to us to wash it the rest of the way. This is fine too, you are getting rid of a lot of the weight and it will save you on shipping.