Probably one of the more unusual elements of German tanks of WW2 is the substance known as ‘Zimmerit’. This unusual material which many tank enthusiasts and modellers have heard of but do not really know much about is as interesting as it is complicated.
The substance known as Zimmerit is referred to as a non-magnetic coating designed to prevent magnetic mines from adhering to the armor of the tank. Zimmerit first appears in 1943. The DB and Alkett factories started applying it from about November 1943 and an order from the German High Command, OKH (Oberkommando des Heeres), dated the 29th December 1943, called for Zimmerit to be applied to tanks, albeit not on the turrets or track guards. A British wartime report from 1945 later confirmed that development of Zimmerit had begun in 1943 as a counter to Russian infantry assault teams using mines held in place by magnets against German tanks.
Tiger II at Bovington showing its hull and turret Zimmerit.
Application and composition
The original order was just to cover the hull of the tank. This is logical as the hull would be the easiest part to reach for enemy infantry armed with magnetic charges. In practice however, it was often applied all over parts of the vehicle, including track guards and turrets, in a wide variety of patterns often varying on a single vehicle.
Examples of different Zimmerit patterns
Different styles of Zimmerit application on the back of the turret of a Panther. Note that neither the cupola nor the roof are coated with Zimmerit.
The actual substance was a mixture of materials almost certainly developed by the firm of C.W. Zimmer AG, Berlin (a well known manufacturer of paints) and is a mix of:
- 40% Barium Sulphate: BaSO4, non-flammable non-water soluble, melting point 1345 C Refractive index 1.64. Main use is in paints and dyes
- 25% Polyvinyl Acetate: C4H6O2, unbonded it is flammable at 104.4 C. Main use is in adhesives and paints (possible ‘Mowlith 20’ sold to the firm C.W.Zimmer in July 1943 by the firm of I.G. Farbenindustrie A.G. Hochst, Germany. Mowlith 20 was a 50% Benzene mixture)
- 15% Ochre pigment: such as Goethite (FeO(OH)) and Limonite (Iron 3 Oxide, Fe2O3) is basically Iron Oxide, non-flammable non-water soluble. Main use is in paints and dyes. This ingredient is responsible for the natural yellow colour of unpainted Zimmerit.
- 10% Zinc Sulphide: ZnS, melting (sublimation) point: 1185 C, non-flammable non-water soluble. Used extensively in infra-red optical materials
- 10% Sawdust: Cellulose fibers, flammable but once bonded will charr creating a thermal barrier.
Unusual application of Zimmerit to side ‘Schurzen’ on these Panthers
An unusual Panzer IV with Zimmerit covering its Schurzen side plates
The paste itself had an unpleasant smell of acetone, but was easy to handle and put onto the vehicle, requiring no preparation of the bare metal surface beforehand. In practice though, a non-corrosive primer was usually applied over the metal surface before the Zimmerit.
This mixture was pasted onto the surface of the vehicle in two applications. The first layer was to be 5mm thick and left to dry for 24 hours, marked out in squares with a metal trowel. A second coat was then applied over this and marked with a metal comb, in order to create a criss-cross pattern to improve adhesion to the first layer. The entire coating was then dried and hardened with a blowtorch. It took less than an hour with a blowtorch to evaporate off the solvents used in the paste and leave it dry, but the whole application, texturing and drying process took a couple of days per vehicle. Even if it were not blowtorch dried, the paste dried out anyway and reached normal hardness within eight days.
Applied correctly, this mixture created a rough hard raised textured surface. It provided not only a poor contact surface for mines, but the texturing also gave a good camouflage finish. Even a small distance between the magnet and the vehicle body reduces the effectiveness of a magnet. This combined with the irregular surface concerned and movement over terrain, was probably quite effective as protection against magnetic weapons.
Factory application of Zimmerit on a Panther
The British investigate
In August 1945, a British team was investigating Zimmerit as a possible means of protection against the Japanese use of magnetic mines in the Pacific. Information had started to be gathered on the substance soon after it was discovered on captured and knocked out enemy vehicles, with samples scraped off and sent for analysis in 1944. Further to the intelligence work on captured samples of Zimmerit, German POW’s had also revealed some of the use of the substance, but it was not until the 14th August 1945 that the British team managed to get some substantive information on the development of Zimmerit and where it came from. That was the day that the British team finally got to the Henschel works in Kassel in Germany. Here the team interviewed the Director of Production about Zimmerit. He recounted that the paste itself was supplied to the Henschel works in drums directly from Chemische Werke Zimmer in Berlin (although other plants were also involved in the manufacture) and had the consistency of soft putty.
Detailed photo of the Saukopfblende gun mantlet from a Jagdpanzer IV showing Zimmerit
The Director of Production revealed that he had thought the order to discontinue the application of Zimmerit was due to the development by the enemy of better anti-tank weapons, rather than because of any safety, production or effectiveness concerns. The order in question had been issued by the OKH on the 9th September 1944 following rumors of Zimmerit causing fires or being flammable. Later German tests would show this to be completely false, but, in either case, there was a significant quantity of Zimmerit left at the Henschel works and the British liberated some 100 tons of it from there. Zimmerit was officially discontinued for factory application from the 9th of September 1944, however, there must have been quantities shipped out to units, as it was not ordered discontinued for field application (which would include foreign maintenance depots and even factories) until the 7th of October.
Panzer IV Ausf H of 26th Pz.Division Italy 1944 with locally applied Zimmerit coating
It is possible that many vehicles got rushed through the application process. As a result some may only have received a single layer of the material due to the constraints on production, or supply. It’s also likely that many vehicles were partially through the process in the factory when the order to discontinue came in. Even at the factories, given the novelty of the material and quality control issues, it is also likely that many vehicles did not get a sufficiently thick two-layer coating. A thin single coating would dry faster so would have aided in speeding factory production. It’s also quite likely that tankers may have imitated Zimmerit on their vehicles using cement.
German soldier spray painting camouflage paint over Zimmerit
Once applied though, Zimmerit was surprisingly durable. Many vehicles have been dug up after having been buried for decades in rivers or swamps and still retain traces of it. Even battle damage didn’t blast it off the surface, as a shell would only cause localized loss of the material.
Battle damaged Tiger showing resilience of material to combat damage
Despite the stated purpose of Zimmerit for protecting against magnetic mines, it’s not clear that it actually worked. Neither the British, Russians, nor the Americans made any notable use of magnetic mines to counter German tanks. Whether or not it actually worked for the stated purpose, it was certainly effective as camouflage and this may serve to explain why so many variations of it exist on a variety of vehicles.
Equipment known to have had Zimmerit-like material applied (click link for photo)
|Ram Sexton||Cromwell||25Pdr gun|
|Panzer 38H(f)||Panzer S35(f)|
Other articles in this series
OKH Order 29th December 1943
WW2 Infantry Anti-tank Tactics, Gordon Rottman, Osprey Elite Series No.124
21 Army Group AFV Technical Report # 26, Amended
British “Zimmerit”, by Jeffrey D. McKaughan, Museum Ordnance July 1995
Mr. Churchill’s Tank, The British Infantry Tank Mk. IV, Schiffer, 1999
ZIMMERIT; Production and Application Methods, Donald Spalding, AFV NEWS, January – April 1983 issue
Imperial War Museum IMG B9098
‘Rubber Zimmerit?’, Bob Eburne, Military Modelling, Vol.29, No.11, October 1999
“Zimmerit” Anti-Magnetic Plaster for AFVs, British Intelligence Objectives Sub-Committee report, Major J.W. Thompson and Mr. C.E. Hollis, July 1945
‘Protection of Jap Tanks Against Sticky Grenades’, Tactical and Technical Trends, No. 25, May 20, 1943.
Zimmerit, Mike Gibb
MUN3435, Imperial War Museum, London
Stuart; A History of the US Light Tank, R.P. Hunnicutt, Presidio Press
Century Tracks No.1, Les sherman Francais de la liberation 1943-1945, Claude Gillono,
Waffen Revue Issue 27
Waffenamt Prüfwesen (WaPrüf) dated 19th November 1944
On Zimmerit, Archive Awareness, 7th August 2013
CAMD RF 38-11369-419, Field Report of substance scraped off German tanks
CAMD RF 38-11355-2219, Laboratory analysis of material submitted for testing Zimmerit, Retrieved from http://stugiii.com/zimmerit.html
Battle Experiences Against the Japanese,HQ European Theater of Operations, US Army 1st May 1945
US Military Intelligence Bulletin, 3rd May 1945, Panzerhandmine 3
Stuart Macrae’s “Toy Box”
‘Supplies to the USSR despatched between 1st October 1941 and 31st March 1946’, Russia (British Empire War Assistance) HC Deb 16 April 1946 vol 421 cc2513-9
ТРОфЕИНАЯ БРОНЕТАНКОВАЯ ТЕХНИКА ВЕРМАХТА (Captured Vehicles of the Wehrmacht) 2007
Memorandum on British Armour No.2, Camouflage, dated 21st February 1945
The US M3 Medium Series in Australia, Paul Handel, 2001
Australian Military Modelling Society, M3 Medium Tank by Al Bowie
The Sherman Tank.com Gallery
Panzer IV: The Panzerkampfwagen IV Medium Tank, 1939-1945 by Kevin Hjermstad
26th Panzer Division in Italy 19433-1945, Daniele Guglielmi
Germany’s Tiger Tanks, D.W. to Tiger I, Thomas Jenzt