My horse is half Connemara so can grow hair like nobody’s business. Not only does he have a wide crest, but he also has copious amounts of really coarse mane hair. I have learnt over the years through trial and error how to deal with it. Mine won't tolerate it being pulled and I don't blame him! I need to pull half it out to get it to more of a normal thickness.
These are my tips and learnings.
Don't use any type or thinning comb or rake. It doesn't remove the hair from the base of the neck so it’s still thick there. You then end up having to plait a thick mane that is all different lengths.
Leave a bit of length. I find it easier to roll them that way. If I need to shorten the mane, I chop the ends of the plaits when I plait. If I need to do it outside of plaiting, I use the technique in this video. How To Shorten The Mane Without Pulling It - YouTube
Vivant Equi Thinning Scissors work well for this.
Lots of little plaits work really well. I do 20 – 25. Trying to do bigger ones, they just end up looking like golf balls because of the amount of hair. I’ve tried all of the ‘plait a thick mane’ techniques I’ve come across. Everything has ended up looking big and awful. Lots of small plaits also has the bonus of making a short neck look longer. It does take a while to do!
I like to roll the rather than fold. Plait the very first bit close to the crest a wee bit looser so it doesn't pull and hurt then the rest of it as tight as you possibly can. If it's not tight it will come apart when you roll.
Sew them. Bands will not hold all that hair. Band the ends but sew once you’ve rolled them. Silicone plaiting bands are fab. Easier on fingers and mane hair. I like using waxed thread, it grips better and is easier to thread through the needle. I use blunt ended, thick needles. They are easier to push through the plait and you don’t risk pricking yourself or your horse. Ones with a big eye are also fab. Much easier to thread when the light isn’t so good.
Use a sectioning comb to get the sections the same width. I like the Hairy Pony one, it has 3 different widths and is metal so the teeth don’t snap like the plastic ones do. Use plaiting clamps to hold the mane you aren’t working on out of the way.
You might be tempted to trim any stray hairs with scissors once you've plaited. I advise against this otherwise next time you plait, there will be lots of little short hairs to deal with. Use product to tame any stray hairs. You can't see them unless your close up so likely only an issue if you're entering turnout classes.
I have had a lot of success using thinning scissors using the method in this video How To Thin The Mane With Thinning Scissors - YouTube In saying that I have recently discovered another secret weapon, HSE Intensive Conditioning Mask. This stuff is so magic it turns the thick coarse mane into a normal mane which makes it way easier to plait. So much so I have done away with using my thinning scissors, only use this and only when I wash for the show. In between shows, if the mane needs some extra conditioning, I use HSE Liquid Silk.
Ask any questions, I've likely tried it