As Germany had developed megnetic mines, which could be easily attached to armour plates by infantry, they were concerned that their enemies might employ magnetic mines themselves. To counter this, the company Zimmer AG came up with a mix of non-magnetic materials (Zimmerit wasn't anti-magnetic (as suggested by an Allied intelligence report from 1945), just non-magnetic), which could be applied on armour plates to prevent the magnets from sticking. The mix consisted of
On 1944-09-09, it was ordered that Zimmerit application was to cease imidiately, beacuse of rumors that impacts from shells would set the Zimmerit on fire, destroying the tank even if the shell didn't. These rumors were investagated, and found to be untrue, but Zimmerit was never re-instated.
Zimmerit was applied to the armour plates in an even layer, which would then be seperated into small squares of approximately five by five mm., after which it should be left to bry in four hours. It was then hardened with a blow torch, after which the Zimmerit shoudl be raised with a spatula, in a series of ridges. It was usually applied at the factories, which resulted in relatively uniform patterns (which varied from factory to factory, though, as not all used the methos described above).
In an OKH order dated 1943-12-29, Zimmerit was to be applied on the following vehicles:
The Zimmerit was to be applied to all surfaces of the hull and superstructure, including surfaces under the armour skirts. Zimmerit was, however, not to be applied to armour skirts, turret, external engine parts, lamps, tools, tracks and similar places. The Zimmerit would have either worn of these places quickly, or wouldn't have had any effect, as the magnetic mines could't have bene placed on the locations (such as the turret), or wouldn't damage the vehicle (such as armour skirts and lamps) anyway. Zimmerit is still often seen on turrets, and sometimes on armour skirts, regardless, but rarely if ever on tools or tracks.
Zimmerit was rarely applied to other vehicles than the ones described above, however one Sd Kfz 251 Ausf. D has been seen with a non-standard pattern. Vehicles not expected to see frontline service (such as self-propelled artillery) weren't given Zimmerit.
Zimmerit was applied in a number of different patterns. Below is a complete list of the patterns applied to different vehicles. Do notice, that some of the patterns were only very rarely seen on some vehicles, and sometimes only on some areas of one vehicle (such as the Pz.Kpfw. Tiger Ausf. E with waffle pattern Zimmerit). All the patterns below have been verified through photographs, though. Any additions to the list is very welcome.
Thanks goes to Christoph Awender, for finding an example of a Pz Kpfw IV with pattern seven