Brush tip

In an email exchange Stephen Martinez asked how to remove the coating from brushes and I suggested swishing in warm water. That didn't work for him, but here's what he wrote next: "Nita, Success! I added a few drops of Dawn Liquid Dishwashing detergent to a very warm glass of water. I let them soak for about ten minutes. Success! The brushes are free of the coating and ready to use." Any other ideas about this?