I have the best wool mitt on the market, CarPro Merino Wool. I have had it for several years and followed the manufacture's instructions, which I will copy for you below. These instructions should work for any Merino Wool was mitt. I will add a couple things from my own experience - do not use the mitt on an exceptionally dirty vehicle. That might seem strange but if you get a lot of grime and grease/tar on it you will loose the advantage of the wool and the design because these things are too difficult to remove without damage to the wool. Also, do not use excessive force when washing. This is true no matter what you use but with a wool mitt it is doubly important. It will do the job with only moderate pressure. Here are the maintenance instructions from CarPro:
"How to get the most out of your Merino Wool Wash Mitt:
Rinse well before first use: It is steam sterilized before shipping however as with any natural product and material that will touch your paint it is best to brush it out and rinse before its first use.
After washing a vehicle rinse the mitt clean of all soap with hose nozzle
Unlike other quality wool wash mitts that must be turned inside out to dry the hide as well (not always an easy process) this mitt is simply swung for a minute using centripetal force to remove the excess water from it.
Then place on a clean grit guard or perforated plastic drain of some type (preferably face down) and allow to dry completely.
Use a pet brush with sufficient spacing between the bristles and gently brush the mitt a couple times to keep fur from tangling over time.
It is normal to experience a little hair loss but there is no need to over brush your mitt
Stow in a clean place for its next use.
Washing Tips:
Fill 5 gallon bucket 3/4 to the top
Measure prescribed amount of car wash
Mix well with your arm
Spray with hose to activate suds
Spray down entire vehicle to remove all loose dirt
Gently Wash from top down rinsing mitt out often
Rinse Mitt in seperate rinse bucket with up and down motion - Always before placing it back in wash bucket to collect more solution
Aggressive scrubbing actions should not be used. Simply allow the mitt to glide back and forth. Use a bug sponge for bugs that have been baked onto the paint.
Use a seperate mitt for wheels with its own dedicated bucket."
