Guaranteed to remove the old and stubborn build-up in fountain pens with the perfect balance of ingredients. Makes your pen write like new again! Instructions: 1. Clean a fountain pen with distilled or tap water until the water runs clear. 2. Fill and flush your fountain pen with Monteverde USA® Pen Flush, repeating to remove any extra ink. 3. Fill and flush with clean water again to remove any remaining Pen Flush.