Cleaning of historic monuments: looking beyond the conventional approach?

Historic monuments are both public and cultural symbols and sources of national pride that provide economic benefits by attracting tourists from across the world. One of the major challenges for the preservation of monuments is their maintenance and renovation. Several attempts to conserve and clean historic monuments have been made using conventional approaches such as the use of synthetic organic polymers and inorganic consolidants. Cleaning is often a time consuming and costly procedure, it includes the protection of the monument from environmental agents, selective removal of buildups of chemicals, dirt, and grime, and the healing of cracks. The rising costs of cleaning historic monuments, the worsening environmental pollution and toxicity due to the use of conventional approach and the increasing demand for sustainable approaches are providing a driving force behind the search for alternative natural techniques for the cleaning and restoration of historic monuments that are environmentally friendly, energy efficient, and cost effective.