 To strengthen the silver enough that it could be manipulated, the mask was placed in an electric furnace, and the temperature raised to over three hours; blackened rust was then removed by brushing the mask with 9% oxalic acid, before heating it again, at for eighteen hours and at for thirteen.The silver was then cleaned again, on both sides, with silver gauze temporarily soldered over the cracks in the back to allow the front to be wiped down.The gauze was removed, the silver manipulated to close the cracks, and new gauze installed, permanently, using soft solder.