KOCHI: Gold cladding and gold plating are two different methods and a structure that has been cladded with gold can withstand weathering for 50 years, said Senthil Nadhan, the amalgamation expert who was deputed by businessman Vijay Mallya to assess the quality of work funded by him at Sabarimala in 1999.“The amalgamation work was conducted at Sannidhanam under the supervision of TDB engineers.
The work was executed by Chennai-based JNR Jewellery. I was brought to Sabarimala when the TDB complained of water leakage in the sanctum sanctorum after completion of the work. I removed the faulty teak wood and replaced the gold covering. After this, Mallya asked me to conduct a thorough inspection to avoid any issue in future,” he said.
Senthil said Mallya donated 30.3kg of 24 carat gold and 1,600kg of copper for the gold cladding. “The gold is flattened into thin foils of 2 microns each and 160 pieces of these foils weigh around 36 grams. The foils are kept in the pages of a book. Later, the foils are melted using mercury and spread over copper sheets to form a gold-mercury amalgam.
The sheets are then heated to vaporise the mercury, which will form a layer of pure gold. Many such layers are added to a sheet to improve quality. JNR Jewellery used seven to ten layers in sections that devotees could not reach out and touch. It was thicker on the roof and areas devotees can access,” said Senthil.
So, is it possible for the gold cladding to start fading in 20 years? Senthil says the chances are rare. The gold covering in high-contact areas that are prone to abrasion and friction may fade. But have the steps faded? The covering on the roof has not lost its lustre and is frequently cleaned by the TDB.
Electroplating is an electrochemical process that coats a surface with a thin layer of metal using an electric current and a metal-containing solution. Compared to gold plating , amalgamation, which is a traditional method, has more quality and will last long, he said. Around 5kg of gold was used for the gold cladding of the dwarapalakas in 1998-99. But for gold plating the idols, only 400 grams of gold was needed.