AGRA: The replicas of the graves of Mughal emperor Shahjahan and his wife Mumtaz Mahal are undergoing a clay-pack treatment for a "facelift" ahead of US President Donald Trump ’s visit to the 17th century monument on February 24.Ever since the two were buried here 368 years ago (Mumtaz Mahal in 1631 and Shahjahan in 1666), this would be the first time that the replicas of their graves are being treated to look clean. The real graves of the royal couple, much austere than their false marble copies, lie in a chamber below the crypt containing them. The real graves are opened only for three days in a year for devotees who come to offer prayers during Shahjahan’s Urs. The 22-step staircase leading to the real graves is narrow and no visiting foreign dignitary in the past expressed desire to see the real graves.Confirming this, superintending archaeologist (science branch) of Archaeological Survey of India (ASI), MK Bhatnagar, said that the mud-pack treatment on the graves was started last week and will be finished by Friday evening.The clay-pack treatment is based on a traditional mix which is used by Indian women to restore their natural glow on the face. "A thick layer of lime-rich clay is plastered over the affected part and left to dry," said an official, adding that when it dries the flakes are removed from the surface with a soft brush and washed with distilled water to clear the impurities.The huge brass chandelier installed over the graves has also been cleaned with "tamarind water". The red sandstone platform at the royal gate, the Chameli floor, the central tank and the sides of the pathways of the fountain inside the monument are also being cleaned.Besides, the ASI has also undertaken cleaning of the monument in a big way to remove the dark spots on the walls and the floors.Earlier, a joint study to look into the factors behind the discolouration of the Taj Mahal by the Indian Institute of Technology (IIT), Kanpur, ASI and US-based Georgia Institute of Technology (Atlanta) and University of Wisconsin (Madison) had revealed that air pollution is the real cause behind the damage to the monument. The study was published in Environmental Science & Technology journal in December 2014. As per recommendation of Parliamentary Standing Committee in the year 2015, the science branch has been carrying out scientific cleaning by using clay pack therapy for entire main mausoleum of Taj Mahal including minarets.The monument had been given the mud-pack treatment five times in the past. While the maiden mud-pack treatment took place in 1994, the second and third ones were given in 2001 and 2008. In May 2014 to get rid of decades of paan and gutkha stains left by the visitors on the interior walls of the world heritage building. In February 2019, the four minarets and north side of the Taj Mahal were again given fresh mud-pack treatment.