Dremel Brass Brush Multipacks - Dremel 26150536JA, These cup-shaped brass brushes from Dremel can be used with a power tool to clean soft metals such as gold, copper and brass.
These brushes are softer than steel so will not leave scratches.
They are also non-sparking.
Dremel 26150536JA 536 13mm Cup Shape Brass Brush Multipack - Pack Of 2