Wurger will know, , but it's a great angle to understand the design ... inspired by the open-top gun mounts the US developed - and provided via L.L. (for example, M-10 Wolverine and M-18 Hellcat - the Soviets received 10 of the former and of the latter 5 copies).
It's called zimmerit. It was pasted on to rough up the metal surface of the armor so that it was harder to stick mines on the tank. This particular pattern is called a "waffle" pattern (I believe). It was discontinued later in '44 on a lot of vehicles to speed up production.
More here...ZIMMERIT AND WHY - The Tiger Collection
Wurger will know, , but it's a great angle to understand the design ... inspired by the open-top gun mounts the US developed - and provided via L.L. (for example, M-10 Wolverine and M-18 Hellcat - the Soviets received 10 of the former and of the latter 5 copies).