I found that my brushes last forever now that I clean them without using any solvent. I use only oil (linseed or walnut) just by dipping the brush in it, and then squeezing out with a cloth. I don't swoosh the brush around in the oil. Then, I clean that up with soap and water (liquid dish soap). Finally, I tamp them dry and apply hair conditioner to them. With the hair conditioner left in, I shape them with toilet tissue strips and just let them be. They dry with the conditioner still in them overnight, and then I take the paper off and I'm left with a perfectly shaped brush.
When I want to use the brush next, I just dip in oil again, squeezing that out to clean off the conditioner, and they're ready. This method even works well with synthetic, good quality brushes such as Escoda's synthetic mongoose, or Winsor and Newton's "Monarch" line.
Hope it helps.
Juan
