Armour plate needed capacity at every level

Was 1930s armour plate constrained by overall production capacity or by heavy capital-ship plate?

Both. The shortage extended through the production system rather than being confined to the thickest battleship-grade plate.

Warship construction depended on more than the availability of the heaviest belt plate. The 1930s constraint affected both total armour output and the specialized capacity for thick capital-ship grades. A fleet programme could therefore be delayed by shortages at several points in the plate-production chain. Nominal shipyard capacity means little if upstream heavy industry cannot supply every required material.