What is a glass fibre pencil?

Glass fibre pencils are commonly used in modelling for cleaning locomotive wheels, commutators and other electrical connections.

The tool looks like a regular pen, but, instead of an ink nib or ballpoint at its end, there is a glass fibre stick that when rubbed gently on a surface requiring cleaning, provides enough friction to clean but won't damage the component.

They do exist in various sizes to provide maximum control.

Opinion is divided as to whether glass fibre pens should be used to clean delicate components, however, the soft tip would have to be used with extreme pressure to cause any damage and their outstanding cleaning ability makes them a firm favourite for many modellers.