Lower firewall and front floor panels

[412usa]

Hi, on the Arnolt the lower firewall, the one the pedals go through, and the front floor panels are made from an aluminium sandwich. Does anyone know what the middle material is. It looks a bit like roofing felt! Thickness of the aluminium and the "meat" would help.
Thanks in advance,

Peter

[412usa]

Ken Oakes the chief draftsman at Brlstol Cars during the Arnolt period tells me that the material is Armourply or Mallite made by William Mallison and Sons and supplied to the aero industry at the time. Armourply uses a plywood core and Mallite uses a balsa core. Mallite was used in certain locations on Concord and was also used in Cosworth and McLaren F1 cars in the 60's. the difficulty is now trying to find some as Wm. Mallison are no longer in business.
Peter