Plastics, brushed steel, ebonite or bakelite… are unscratched with mesh, micro mesh and liquid abrasive regarding the depth of each scratch, crack and spit.
Metal parts are jewelry-like treated with green compound then the rouge “jewler”polishing compound give them a lovely shining effect.
When the damages are not very serious, I use 100% natural cream polishes, they are meant to protect the environment and our hands.
In that case all the job is handworkly done.
The first final step is done with another liquid glossy abrasive or some different types of micro mesh (very fine sandpapers).
They can be treated with blue polishing compound aswell, every pens are different and require their own treatment.