Despite the name, I think it's the best brush cleaner around. I've revived 6 year old, dried out paint brushes (the kind that could kill someone) back to almost new. For my really bad brushes, I coat the bristles & let them sit for a day or two (occasionally massaging the soap into the bristles). You'll know when it's done it's job, the bristles will be pliable. Just rinse really well, pat dry & then add a little oil back to the brush. I've saved so many brushes. It's been harder to find in the art stores but here's a link to purchase.
Don't you have a container of old, paint laden brushes sitting around your studio that you would love to use again?