File No.: Battle Relic # 29
Title: "Zimmerit"
Investigation made at: An undisclosed location in the Netherlands
Period Covered: 1942 - SEP 1944
Date: NOV 2011 to JAN 2017
Case Classification: Study of a chemical component named “Zimmerit” which in Nazi Germany was used to create a non-magnetic layer on armored vehicles against magnet-borne anti –tank shape charges. Recreation of Zimmerit and testing its (non-)magnetic and (in-)flammable properties.
Case Status: Case Closed
REASON FOR INVESTIGATION: In an abundance of publications the substance “Zimmerit” is described. This non-magnetic anti magnetic charge substance was only used by Nazi Germany; not by its enemies. It gave a very distinctive look to their weaponry. It is this agency's intention to learn if Zimmerit was in fact non-magnetic and of it would ignite.

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Applying recreated Zimmerit
on an original World War Two
Nazi tank part

SYNOPSIS:
Zimmerit was a non-magnetic coating produced for Nazi armored fighting vehicles during World War II for the purpose of opposing magnetically attached anti-tank mines, although the Third Reich was the only country to use magnetically attached mines against armored vehicles in any significant number. Zimmerit was developed by the German company Chemische Werke Zimmer AG. The coating was a buffer that prevented direct contact of magnetic mines with metal surfaces of vehicles. It was normally ribbed to increase overall thickness. The magneto static field decreases very rapidly, with the increase of distance; the non-magnetic coating holds the magnet of the mine too far from the steel of the vehicle for it to stick to it.


1926 commercial logo of Zimmerit
corrosion protective coating

Zimmerit was applied to some tanks and casemate-style closed-top self-propelled guns and tank destroyers produced from DEC 1943 to 9 SEP 1944. It was only rarely applied to open-top Armored Fighting Vehicles. The rough appearance of the coating gave a distinct appearance, for one type a "shingle-like" look to the vehicles it coated. Application of Zimmerit was usually done at the tank manufacturing plant. Zimmerit was discontinued from factory application on 9 SEP 1944 and from field application on 7 OCT 1944 because of concerns that projectile impacts could ignite it. These proved false, but the order was never withdrawn. Applying and drying Zimmerit added days to the production of each vehicle, which was unacceptable because of the shortage of tanks in the last stage of the war. No similar material was used on post-war tanks as the widespread use of man-portable HEAT (High Explosive Anti-Tank) rockets such as the American Bazooka and the British PIAT (Projector Infantry Anti-Tank) made magnetic mines obsolete.

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Zimmerit coating on Third Reich tanks

   
Period images of the use of the Hohlhaftladung

Ingredients
Zimmerit was made up of the following:
40% Barium Sulphate, BaSO4 - is made from Barium (Ba) treated with Sulpheric acid (H2SO4), and is water-insoluble
25% Polyvinyl Acetate, PVA - commonly known as white carpenters glue
15% ochre pigment,  An earth-toned coloring material
10% Zinc sulphide and ZnS - a natural mineral, and a Zinc ore.
70% Zinc Sulphide and 30% Barium Suphate give Lithopone, a white pigment
10% sawdust

Given the fact that Zinc Sulphide and Barium Sulphate make up for 50% of the ingredients of Zimmerit and that both chemicals are used to produce Lithopone, this agency has decided to use Lithopone as final product as an ingredient for 50% of all Zimmerit to be manufactured and not to use the precursors Sulphide and Barium Sulphate.


Two leading sources for purpose and ingredients of Zimmerit
1) Post-war interview with chief engineer Robert Pertuss of the Henschel tank manufacturing company in Kassel, Germany.
2) British Intelligence Objectives Sub- Committee report "Zimmerit" Anti-Magnetic Plaster for AFVs, by Major J.W. Thompson and Mr. C.E. Hollis.

TIGER I : 50th Anniversary Commemorative Edition Hardcover – Illustrated, 1992
by Uwe Feist  (Author, Illustrator), Bruce Culver (Author)
Published by Ryton Publications, Retford Notts, UK, 1992


The purpose and initial application of Zimmerit are best described in an interview with Herr Robert Pertuss, chief engineer at the Henschel tank manufacturing company in Kassel, Germany:

"One day Herr Kniepkamp (of Heereswaffenamt) showed up at Kassel and reported that the Russians had used magnetic mines, which tank hunting teams attached to the sides of our tanks and could be made ineffective by a thick grooved layer of some form of cement applied over the surface of our vehicles. With this method the magnets would not get a strong enough grip to keep the mines in place. Our Purchasing department was able in an afternoon to telephone I.G Farben chemical company to find out what materials would be suitable, available and quickly obtainable. It had to be fast drying and stone hard when dry. Two days Later the first drums of "Nitro-Spachtel" arrived. Using improvised tools made out of sheet metal we made a test application. In only 3 hours the material was dry and could be painted. The drying time shortened considerably when we used a blow torch to dry the material. Tigers ready for delivery the day after the "Nitro-Spachtel" arrived were coated and painted and we delivered Tigers with the Material until the end of production."

From: AFV NEWS, Jan-Apr/1983 issue
http://web.archive.org/web/20071005162036/http://www.afvnews.ca/zimmerit.html
visited as recently as 29JUN2016


We found that most of the publications on the ingredients of  Zimmerit repeat the content of one leading publication in the JAN-APR 1983 issue of Armoured Fighting Vehicle News Magazine.

Information from a secret British Intelligence Objectives Sub- Committee report:

The information is now unclassified and entitled, "Zimmerit" Anti-Magnetic Plaster for AFVs, which was reported by Major J.W. Thompson and Mr. C.E. Hollis. The report is dated July 1945, and is not complete due to insufficient information, or the failure to locate persons with detailed knowledge of the subject. The investigation was started with the hope that a way might be found to defeat magnetic mines used against British armor in the war with Japan. In 1943 the Germans adopted a thick coating for the vertical armored surfaces of their tanks. This coating was designed to defeat the affects of mines placed on armored vehicles, mainly tanks, by determined Russian infantry assault teams. The mines were attached to the tanks and held in place by magnets built into the bottom of the mines. The function of the "Zimmerit" was simply to provide a non-ferrous magnetic gap between the steel armor and the magnets, in other words a non-magnetic stand-off. Early in 1944 samples of Zimmerit were taken from captured vehicles and instructions for its use obtained from prisoners of war. The composition of Zimmerit was analyzed by C.S.A.R. and found to be the following:

Polyvinyl Acetate-25%, as binder or glue;
Wood Fiber-10%, as filler;
Barium Sulphate-40%;
Zinc Sulphide-10%;
Ochre Pigment-15%, for the dark yellow color.

On August 14, 1945 the investigating team visited the Henschel Werke at Kassel, Germany and interviewed the Director of Production and Production Engineer. The following information was obtained. The Zimmerit was received in drums from Chemische Werke Zimmer in Berlin, but they thought production had taken place in various centers because of the large scale demands, and because of factory dispersal. The material arrived in a consistency of soft putty (others have compared it to paste, plaster or plastic). It contained a volatile solvent smelling like acetone. No thinners were added before use as it worked very easily even when handled by inexperienced personnel. The surface of the tank did not need to be prepared before applying Zimmerit, but it was normal to coat the vehicle with anti-corrosive primer. The Zimmerit was applied to the surface in two coats, using a sheet metal trowel. The first coat was 5mm thick and was marked out in squares using the edge of the trowel. This coat was allowed to dry at ordinary  temperatures for 24 hours. The second coat was applied thinner and marked in wavy lines with a metal comb. The crisscross squares increased the adhesion of the second coat, while the comb markings gave a camouflage finish, plus poor contact for mines. After the application of both coats, the surface was treated by a gas blow-lamp to harden it. This took about an hour per tank and no difficulty was experienced in getting satisfactory hardness without the Zimmerit becoming brittle. (I have seen samples of aged Zimmerit and it reminded me of compressed sawdust.) During the hardening process the solvent was removed by the heat of the blow-lamp on the surface. The chief thing to watch was not to leave any soft spots which could be brushed off the vehicle if not hardened properly. If the Zimmerit was not heated with a blow-lamp it took eight days to harden. This was impractical considering the urgent need of tank delivery to the front. The Production Engineer of Henschel Werke said that the company did not help in the development of Zimmerit, but simply applied it to vehicles. He thought that Zimmerit was dropped late in the war due to the development of better anti-tank weapons. No mention was made of how successful Zimmerit was, however, when the British Army captured the Henschel Werke they removed about 100 tons of Zimmerit. The investigating team next visited the Karl Freudenburg A.G. in Weinheim, Germany and talked with the company’s Polyvinyl Acetate experts. Again, this company had not helped in the development of Zimmerit, but did work on the P.I.B. mineral oil adhesives for sticky bombs. The Polyvinyl Acetate was used as an emulsion in camouflage paints and as a solvent such as Ethyl Acetate and Toluene during the war. It was mentioned that C.W. Zimmer of Berlin was well known for paint manufacture during that time, and probably used Polyvinyl Acetate.

On visiting I.G. Farbenindustrie A.G. Hochst, Germany, the Plastics Development Manager and  Production Manager were interviewed. They said that they had heard of the C.W. Zimmer Co., but also knew nothing of the development of Zimmerit. It was also mentioned that such things were kept secret. After referring to the company’s records it was learned that Mowilith 20 (a Polyvinyl Acetate) was sold to the C.W. Zimmer Co. In July 1943, but they had no idea if the company or its personnel still existed. The general properties of Polyvinyl Acetate were discussed. Mowilith 20 was 50% benzene solution (this is what smelled and was burned off with blow-lamps). It had an average MW of 3500 (Staudinger viscosity method, 1 - 2% solution) and a melting range of 40 to 50 degrees C. It was also confirmed that the blow-lamp would remove the solvent and adhere the Zimmerit to the armor, thus increasing its resistance to shock. In regard to adhesion, it was suggested that a clean or just painted surface would be better than a greasy or rusty one. Also, that Polyvinyl Acetate with a pigment mixture (Zimmerit had 15% ochre) were somewhat water-resistant, but due to thermal behavior of Polyvinyl Acetate its use was limited in plastics as it became brittle when cold. In conclusion, the team decided that the C.W. Zimmer Co. was responsible for Zimmerit and every effort should be made to contact them. They also were wondering if Zimmerit, thinned down, could have been sprayed on vehicles to speed up application time. However, no follow-up research was done due to the end of WW2.

Battlefield myth testing experiments
A. Magnets: Original magnet charge magnets, normal magnets and neodymium magnets
To test original, period Zimmerit coats and self-made Zimmerit, we acquired an array of magnets of different strength and sizes. From an online auction website we even bought a complete set of original magnets of a Nazi magnetic hollow charge; or “Hohlhaftladung”. On 06 OCT 2014, the seller named “Pjotr” from Poland, answered us by e-mail when asked where he’d found the magnets:

"Hello! I found magnets on defensive line of Erich Koch gaulajter of East Prussia. The line defended the access for 3 months to prus eastern. Ran about 12 km to the east of Suwałki.Magnets found in “Nowa Wieś,, willage.On my area fights lasted from the 1944r summer to the 1945r winter. The Area very much is permeated war relic."

Just off Utah Beach in Normandy, a French Army Engineers officer demonstrated an inert but original World War Two era "Hohlhaftladung" to this agency in June 2015.

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Personal demonstration of the Nazi Hohlhaftladung antii-tank mine.

Due to local restrictions regarding weapons, ammunition and ordnance, we consider our Plexiglas model with mounted magnets and handling ring the next best thing to a hollow magnetic charge.


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Normal and neodymium magnets were easily procured online and in local shops.
 
B. Preliminary study: testing magnets on actual Zimmerit
- Panther D tank in Breda, 13 NOV 2011
- Panther tank, Technik Museum, Sinsheim, Germany, 17 AUG 2014
- Schulungsfahrzeug and canon in the Deutsches Panzer Museum in Munster, Germany, 20 MAR 2015
 
Panther D tank in Breda, 13 NOV 2011
For a description of this tank see also Battle Relic # 29; Sub File No.: 15-A (15-1).

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Panther tank, Technik Museum, Sinsheim, Germany, 17 AUG 2014

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Schulungsfahrzeug and canon in the Deutsches Panzer Museum in Munster, Germany, 20 MAR 2015
To test the Zimmerit in the German Panzer Museum in Munster, we needed a special Photography- and measurement Permit which consisted of a pass and a high-viz vest, allowing us to even climb on top of vehicles like the Königstiger tank.

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C. Platform: Original World War Two Nazi right front mudguard of Königstiger (Tiger II) tank
This agency procured an original World War Two vintage mudguard of a Königstiger tank at the 18 MAY 2013 Militracks event in Overloon, the Netherlands. The German businessman selling it, claimed to have found it on a forest floor near Berlin just shortly before the transaction. It was not buried in the ground, it just lay there, he said. This is consistent with what numerous period photos of Königstiger tanks which hardly ever show all 12 mudguards still attached to the vehicle. It would only take hitting any roadside obstacle to lose one or two of these steel mudguards.
The original mudguard is considered to be the next best thing to using a complete World War Two Nazi tank.

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Right hand side mudguard, second segment from the front.
Usually not treated with Zimmerit, although video evidence proves an exception.
Click here for footage of a captured German Königstiger II tank featuring mudguards treated with Zimmerit.

D. Zimmerit test in five stages
1) Sandblasting the mudguard and coating it with primer paint, 18 MAY 2016

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2) Mixing the ingredients and applying self-made Zimmerit to the mudguard, 8 JUN 2016

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3) Painting the mudguard in Nazi camouflage scheme, 27 JUL 2016

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4) Testing the Zimmerit for its (non-)magnetic properties, 15 JAN 2017
The hardened-out product was tested on this date using various magnets in a wide variety of magnetic strength.  From household kitchen or toy magnets, to original World War Two Nazi "Hohlhaftladung" magnets, to strong modern-day magnets and finally a Neodymium magnet. We found that only the stronger modern magnets are capable to carry their own weight on the iron mudguard treated with Zimmerit. They have the same magnetic forces as felt by us when we applied them to original Zimmerit in Breda, Sinsheim and Munster.

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CONCLUSION:
Not only has this agency been able to recreate Zimmerit but it has established that this substance has certain non-magnetic features comparable with original Zimmerit tested with the same magnets. Given the fact that this agency has applied Lithopone as an ingredient for 50% of all Zimmerit to be manufactured and not to use Lithopone's precursors Sulphide and Barium Sulphate combined with the established non-magnetic features of the product, there now is a patent application pending for "Timmerit(|Tm)(c)" as we have named our product.
 

EXHIBITS:
The Zimmerit treated Königstiger II mudguard now serves as a privacy protective screen on the balcony of an apartment in a densely populated urban area:

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