Three of six Stordy Coil Annealing Furnaces used to soften coil prior to rolling. These furnaces were capable of holding 16t ( see charging machine in right of picture) each...made up of 6-8 coils. During the cold rolling process aluminium work hardens and becomes more difficult to roll and to form if near to finished gauge. Coils were heated by electric elements with a forced air circulation system to provide rapid convective heat to minimise grain growth during annealing. Two of the furnaces had an inert atmosphere of partially combusted butane to prevent oxidation of magnesium car trim alloys. If a product was being supplied as a quarter (H12) , half hard ( H14) or three quarter hard ( H16) finished temper, the coil needed to be annealed before a 15%, 30% or 45% guage reduction on the finishing pass - generally carried out on the Robertson cold mill.