Back to the light
The most spectacular aspect of the restoration work was the glass roof. Just as in 1900, colossal scaffolding was erected in the Nave. For two years, a Titanic task was undertaken to bring fresh light into the building.
1,300 tons of steel and 150,000 square feet of glass panels were needed to fully repair the frame and the glass roof. © Agence Perrot, cliché Alain Baudu
The damage to the steel structure was due to several factors. In 1900, the steel used in the structure was more solid than that used to make the Eiffel tower. However it was less flexible, and put more pressure on the strength of the rivets which ultimately began to give way. Moreover, the sheer weight of so many temporary decors hung from the structure for different shows had weakened it. Finally, through insufficient fresh paintwork, rust had started to attack the base of the pillars.
After the foundations were consolidated in 2001, EMOC set out to deal with the steel frame in 2003. The steel weighed a total of 8,500 tons, more than the Eiffel Tower. At the centre of this engineering feat was its most impressive device: an enormous yellow prop, a sort of scaffolding using 64 jacks that stood at the centre of the building. This was capable of raising the dome by around a sixth of an inch to separate it from the rest of the structure and enable the restoration of different parts of the steel structure. This lifting work required great know-how as pushing too hard might cause the structure to break. This huge-scale operation was successfully completed with 1,500 rivets being changed.
The most spectacular job was to change all the glass in the roof. Pane by pane it was dismantled. The glass plates were no longer up to standard and were replaced one by one. Instead of the unpolished reinforced glass used in 1900, the new material used was laminated glass that enabled the lightweight quality of the original to be preserved. The panes were made less wide to maintain the original pattern. In all, more than 16,000 m2 of glass was replaced, and the Grand Palais recovered the graphic purity, brilliance and transparency that had made it so unique.
After the foundations were consolidated in 2001, EMOC set out to deal with the steel frame in 2003. The steel weighed a total of 8,500 tons, more than the Eiffel Tower. At the centre of this engineering feat was its most impressive device: an enormous yellow prop, a sort of scaffolding using 64 jacks that stood at the centre of the building. This was capable of raising the dome by around a sixth of an inch to separate it from the rest of the structure and enable the restoration of different parts of the steel structure. This lifting work required great know-how as pushing too hard might cause the structure to break. This huge-scale operation was successfully completed with 1,500 rivets being changed.
The most spectacular job was to change all the glass in the roof. Pane by pane it was dismantled. The glass plates were no longer up to standard and were replaced one by one. Instead of the unpolished reinforced glass used in 1900, the new material used was laminated glass that enabled the lightweight quality of the original to be preserved. The panes were made less wide to maintain the original pattern. In all, more than 16,000 m2 of glass was replaced, and the Grand Palais recovered the graphic purity, brilliance and transparency that had made it so unique.
The story of mignonette green
So what was the best colour for the restored steel structure? Over the years, layers of paint had covered it completely, the result in 2001 being an overall greyish impression. Painstaking studies and analyses revealed that the original colour was close to pale green. Physical and chemical analysis of the samples enabled the different ingredients and pigments used in the successive layers to be analysed. The researchers set out to find the original product and luck was on their side. The manufacturer who supplied the paint in 1900 was still in business: this was Ripolin, and the company still had archives from the period. The original colour chart was found and revealed that the tone used had been "vert réséda pâle", mignonette green. So the restored steel frame was repainted in strictly original livery.
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