Dry cleaning is vital in poster restoration for safely removing surface dirt, dust, and grime without using liquids that could damage the paper. This meticulous process helps restore the poster's original appearance and prevents further deterioration. By eliminating abrasive particles, dry cleaning protects the poster from future wear and tear. Additionally, it prepares the poster for subsequent restoration steps, ensuring treatments like pH adjustment and repairs are more effective. Dry cleaning is essential for preserving the artwork's integrity and longevity.