when should a person replace this brush with a new one?
I have had mine for a long time. I'm not sure if because it is so old it is losing its effectiveness. What are signs of aging on this brush? Thank you!
If your brush has lost its original shape and has gotten "bushier", then it is time to buy a new one. I have had mine for 3 years now and it is still in perfect shape. The trick is to clean them once a week with a mild shampoo, ( I use baby shampoo),and let them air dry while laying flat.
2 years, 1 month ago