Got a great question about the best way to clean up a matted mane. My wife, Diana, is very good at this. Here's the procedure I learned from her:
Preparation: Teach your horse to stand quietly while being groomed. Set aside at least an hour to work on the mane.
Product: A bottle of tail and mane detangler and a wide-tooth comb.
Procedure: Work with a three inch section of the mane at a time. Saturate it with detangler. Work from the end of the hair back toward the base.
Start four or five inches from the end of the first section. Grab the section of hair firmly with one hand and brace against the horse's neck. This effectively shortens the mane and reduces the chance of breakage.
With the combing hand, gently comb this short section out. If you encounter a tangle, spray a little more detangler and gently work through it with the comb. When that short section is done, grab a bit higher with your other hand and continue work on that section, proceeding back to the base of the hair.
When the whole section is done, start a new section. Rewet with tangler as often as needed. Most detanglers do not need to be rinsed out. Leave the horse standing tied until the mane is dry. Dry comb the mane very gently the next day. The more often you comb or brush the mane, the less likely it will be to get really matted.
FYI, I'm not crazy about hoodies (spandex hoods that cover a horse's head and neck) but that is certainly an option if you need to keep your horse's mane nice for a particular event. Just be sure you don't make that a regular way of life for him. His mane needs to be free.