Experience with a horse hair brush?

For whatever reason I have just never bought one so I did.  I haven't used it yet because after two lathers the thing still freakin STANKS lol.  It feels pretty stiff.  What is the break in like?  Does it soften up like boar?

I have a Vie Long horse hair brush. Small knot but a great brush. I guess the tips soften up more compared to a boar but you need to be careful as the hair are more brittle and please make sure not to apply more pressure while loading soap. They require combing after drying as the hair tend to get tangled.

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Not sure it'll work for you, but my experience with my only horsehair brush (Vielong) was fairly simple in eliminating the odor.

Thorough bristle soak and agitation of bristles with Dawn Platinum water solution.