Bob Ross Brushes are meticulously crafted to Bob's exact specifications, tailored for use with oil paints. To maintain these brushes and knives in optimal condition, it's essential to clean them using Bob Ross odorless thinners or other compatible art thinners or turpentine products. Avoid using water for cleaning, as it can shorten the lifespan of the brushes and palette knives and may lead to cracking and peeling of paint on their handles