Pen Brushes and Mini Buffing Wheels: Sizes, Materials and Uses

Every polishing job has places a big wheel cannot reach: corners, slots, threads, engraving, jewellery findings, die cavities, the inside of a tube. Pen brushes and mini mounted wheels exist for exactly that. They run on a 2.35mm or 3mm shank in a rotary tool, and choosing between them comes down to three numbers — diameter, length and material.

Three size families

The WanHu range falls into three groups. The smallest, around Ø10.5–12mm, is for fine detail: Off-White Cotton Cloth Pen Brush Ø10.5-12mm × 25mm in cotton cloth, White Wool Felt Pen Brush Ø10.5-12mm × 25mm in wool felt, Bleached Cotton Cloth Pen Brush Ø10.5-12mm × 25mm in bleached cotton, or White Pig Bristle Pen Brush Ø10.5-12mm × 42mm in pig bristle, all on a 2.35mm rod. The middle group, around Ø17–22mm, is the everyday size: White Wool Pen Brush Ø17-22mm × 42mm in white wool, Hexagonal Black Pig Bristle Pen Brush Ø17-22mm × 42mm in hexagonal pig bristle, or Brass Wire Pen Brush Ø17-22mm × 42mm in brass wire. The largest group, around Ø19–25mm, covers broader contact: White Wool Pen Brush Ø19-25mm × 42mm and Black & White Wool Pen Brush Ø19-25mm × 42mm sit here.

Pen Brush Colour Chart — The colour chart shows the full material and colour range side by side.

Diameter	Length	Shank	Typical work
Ø10.5–12mm	25mm	2.35mm	Engraving, fine detail, jewellery
Ø10.5–14mm	42mm	2.35mm	Slots, threads, recessed areas
Ø17–22mm	42mm	2.35mm	General detail polishing and deburring
Ø19–25mm	42mm	2.35 / 3mm	Larger recesses, mould and die work

Material decides what the brush does

Pig bristle is the firmest natural fibre and works well with cutting compound on metal — see White Pig Bristle Pen Brush Ø10.5-12mm × 42mm or Black Pig Bristle Pen Brush Ø19-25mm × 42mm. Wool is softer and is the usual choice for final colouring: White Wool Pen Brush Ø10.5-12mm × 42mm or Black & White Wool Pen Brush Ø19-25mm × 42mm. Horse hair sits between the two and suits light deburring — White Horse Hair Pen Brush Ø10.5-12mm × 42mm or Octagonal Brown Horse Hair Pen Brush Ø17-22mm × 42mm. Cotton cloth and cotton yarn give a clean, lint-free finish on plastics and soft metals: Off-White Cotton Cloth Pen Brush Ø10.5-12mm × 25mm, Bleached Cotton Cloth Pen Brush Ø10.5-12mm × 25mm and Pure Cotton Yarn Pen Brush Ø10.5-14mm × 42mm. Wool felt such as White Wool Felt Pen Brush Ø10.5-12mm × 25mm carries compound densely for very fine work. For metal removal rather than polishing, brass wire Brass Wire Pen Brush Ø17-22mm × 42mm and stainless steel Stainless Steel Pen Brush Ø17-22mm × 42mm are the two options.

Hexagonal, octagonal and round

Shape is not cosmetic. A round brush gives even contact; a hexagonal brush such as Hexagonal White Wool Pen Brush Ø17-22mm × 42mm and an octagonal brush such as Octagonal White Wool Pen Brush Ø17-22mm × 42mm present corners that reach into grooves and edges more effectively. If you are polishing a flat recessed face, take the round; if you are chasing a corner, take the faceted one.

When a mounted wheel is better than a brush

If the goal is brightness rather than texture, a small cotton wheel beats a brush. White Cotton Mounted Buffing Wheel with 6mm Shank carries a 6mm shank for drills and larger rotary tools, and Mini Mounted Buffing Wheel Kit 19 Pcs Ø25mm with 2.35 / 3mm Shank is a 19-piece kit with 2.35mm and 3mm shanks for the finest work. Mount them with the Steel Tapered Cone Mandrel for Buffing Wheels mandrel or the hardware in Steel Mandrel Mounting Hardware Kit for Buffing Wheels so they run true at speed.

Fitting and running them

Match the shank to the collet — 2.35mm and 3mm are not interchangeable — seat the shank fully, and run at a speed appropriate to the diameter. Small tools are unforgiving of excess pressure: let the tip do the work and keep it moving.

Not sure which item fits your line? Send the workpiece material, the starting surface, the target finish, machine type and speed, plus the quantities you need — request a quote and we will come back with a matched combination and lead time.

Always follow the machine manual and the safety information supplied with the product, and wear appropriate eye, hand, hearing and respiratory protection.