This is where it sometimes becomes impossible to brush polish, as commonly occurs, pieces with hidden and apparently unreachable corners. Therefore, we turned to the centuries-old tradition of the trade, recovering the ancient method of thread polishing. A simple and effective method of polishing otherwise inaccessible concavities. An elementary process that consists of repeatedly sliding a cotton thread forwards and backwards in the cavity to be polished, applying slight pressure until achieving the desired result. A slow and precise process, the repetition of a simple gesture like a drop of water smoothing the cliff face.