Mechanically polishing out the engraving is discouraged, since the early post-war plastic has already lost plasticisers and weakening of the wall can lead to body damage. An ultrasonic bath can dissolve the gold inlay but also attacks the sealing compound and is therefore risky. The recommended middle path is to have an engraver or locksmith cover the gold inlay with the usual black wax stick, which significantly tones down the engraving without harming the substance. Generally there is also an argument for keeping engravings as part of the pen's history. Careful polishing with Wenol is acceptable on old models too, as long as the work is not too aggressive; for repairs HMS is recommended.