when polishing we use different compounds, starting with a rougher, pre-polish, compound to remove sanding paper scratches and fire scale that forms while soldering. This compound is brown in colour as is also known as tripoli.
We then move on to other compounds with an increasingly finer grain. For silver I use the green compound for polishing followed by the red one, called rouge, for shine. For other metals there are specific products, each with a specific colour – blue, white, etc.
The problem is that polishing tools – felt tips, brushes, pompons – are the same for all compounds but it’s not a good idea to use the same one all the way through. Ideally we use a different set for each compound.
To avoid confusion I have a very simple technique to tell my tools apart: I paint a line in each one using a different colour nail polish for each corresponding polishing compound. In my case, pink for tripoli, green for green and red for rouge (I should get a brown one but that’s what I had available and it still works).
You don’t need nail polish for this. Any paint that sticks to metal will work and like this you can easily avoid getting your rouge pompon dirty with green polishing compound by mistake.