I'll need to replace the wood firewall in my '21 Roadster next spring.
Originally, were they plain bare wood, painted, varnished, covered in bituminous roofing tar???
Painted. The finish was glossy when newly applied and just dried but it dulled rather quickly to a semigloss or satin.
I never have owned a mid-production T with a wood firewall, so have a question. I hope John Regan will kick in here, since he is the firewall king! Are the 15-23 firewalls veneered?
I don't know if they're supposed to be or not, but I did my 22's in a oak veneered plywood, stained it and finished it with Varithane. Although it was probably really supposed to be black (every bloody thing else was).
The original firewall in my 15 was made similar to the older T firewalls. It has lumber core boards running vertically and veneer on both sides. However the grain of the veneer runs vertical which I believe differs from the earlier firewalls.