when did they start and stop using zimmerit and just what was it, i know what it was used for but a friend of mine said it was only on the early ones, is this true ?
It start in mid 1943 and finished appling the Zimmerit in october 1944.
The end of the spring and the beginning of summer of 1943 marked the most algid point in the German offensive operations, and was in this period that the zimmerit was introduced. The zimmerit was a material applied to all the vertical and inclined surfaces of the German armored vehicles in an effort to counteract the Soviet magnetic and adhesive mines, that need a flat steel surface to adhere enough time so that the explosive damages or destroy the vehicle. The horizontal surfaces didn’t require such a protection because the mines could simply lean on, without necessity of being stuck. The development of the zimmerit offered protection against the magnetic mines simply placing a layer of non metallic material between the imam of the explosive load and the vehicle. The zimmerit was not an antimagnetic material, but it created an irregular surface that reduced the contact area to place the mine, which fell for their own weight, helped by the vibration of the vehicle in movement.
Composition
According to a British report of 1945, the zimmerit was developed in Berlin by the company Chemische Werk Zimmer AG (of there the name), was basically a polymer and it consisted on 40% of barium sulfate, 25% of polyvinil acetate, 15% of pigment ocher, 10% of sawdust and 10% of zinc sulfate. The zimmerit was used until half-filled of 1944, when it was retired progressively for its fail over improved antitank mines (the rockets in particular) and because usually enter in combustion before the impact of some projectiles, besides the fact that the German operations of that period were essentially of defensive nature.
Application
For their application, the product was not used as paint and therefore it didn’t require to be diluted. The surface of the vehicles neither required a special preparation, the base of traditional anticorrosive painting was only used. The zimmerit was applied in two layers with a metallic spatula. The first layer was of about 5 mm of thickness and was made a drawing in form of squares using the border of the spatula. This drawing favored the adherence of the second layer. The first layer of zimmerit allowed to dry off to ambient temperature during 24 hours. The second layer was marked with irregular lines with a metal tool in comb form. The final drawing gave him a rough and irregular appearance. After having applied the two layers, was carried out a drying by means of a gas torch to harden them. This took around one hour for vehicle. The final result was seemed the one that have the pressed sheets of cardboard and it was not brittle, but compact and very stingy to the metal. If the forced drying was not used, to the zimmerit took eight days outdoors to become hard. Also, the drying to high temperature increase their resistance to the blows. The zimmerit was also resistant to the water, but due to the behavior of the vinyl acetate was brittle to very low temperatures. There are many pictures and movies in those that armored vehicles are come with parts of the zimmerit removed. A great quantity of historical references indicates that several types and different zimmerit designs were used. The applications in the factory were generally neat and uniform apparently, while the applications in the field were not it so much, mainly keeping in mind the battle conditions and the available time for the company to complete the application. The application increased considerably the weight of the vehicles. According to the British report that is based this article, a StuG required 70 kg, a Panzer IV, 100 kg; a Panther, 160 kg and a Tiger I, 200 kg. Additionally, the texture of the application that was different for each vehicle type, and served as camouflage, especially when the vehicles were in forests, because the rough surface looked like that of the trunks of the trees or that of the earth in woody areas. According to the camouflage required by the vehicles that it depended on area of operations, was applied additional painting with the required colors. However, in many circumstances, the soldiers carried out their own camouflage using branches, trunks, mud and covering the tanks first with engine burnt oil and sprinkled sand.
Different designs
The following list tries to be a synopsis of types of vehicles and the zimmerit design generally associated with each one. Anyway, you notice that there were exceptions (especially for the applications in the field) that can, in occasions, contradict this list. This is a very general guide, for what is important to consult all the possible references before using it in a model, if what is looked for is historical accuracy.
thank you Panzerknacker, that is very helpfull and the link too. what can i say apart from thanks m8 
Thank you Panzerknacker, that is very helpfull and the link too
Yu re welcome. Is a funny thing that neither the americans or the russians have in inventory a magnetic mine , the zimmerit was installed because some tanks were lost to captured panzerhandminen used by the russian and the germans tough they would copy that design and use it in large scale against the panzers, never happen, but of-course and aditional protection never hurts.
Zimmerit in Pv V.
In here you got more info:
http://www.geocities.com/Augusta/8172/panzerfaust1.htm#zimmerit
so basicly the germen had the magnetic mine thought that others would have them too so they made up the zimmerit just incase, got them selves a little worried there but like you said “of-course and aditional protection never hurts”
Exactly . The problem was that the aplication of zimmerit also take his time and delayed the production of armor a bit, and there was some rumours between the panzercrew that it gought fire after beinbg hit with bazooka (untrue because it carry no inflammable material in the paste)
Wathever the reason the Zimmerit was no more applied in the panzers manufactured in 1945.
According to a British report of 1945, the zimmerit was developed in Berlin by the company Chemische Werk Zimmer AG (of there the name), was basically a polymer and it consisted on 40% of barium sulfate, 25% of polyvinil acetate, 15% of pigment ocher, 10% of sawdust and 10% of zinc sulfate. The zimmerit was used until half-filled of 1944, when it was retired progressively for its fail over improved antitank mines (the rockets in particular) and because usually enter in combustion before the impact of some projectiles, besides the fact that the German operations of that period were essentially of defensive nature.
Um… what I heard is that the Zimmerit was concrete put on tanks to stop mag mines from getting on. Correct me if im wrong.
Concrete armor was also used specially in some Stug IIIs late variant, and remote controlled demolition vehicles ( see my topic special purpose Panzers) but if you look at the composition of Zimmerit you ll find out is not concrete.
Read once in some book on German AFV´s that the concrete on the Stug´s actually had a negative effect (suppose it helped projectiles not to bounce off sloped armour?) according to German tests, and that concrete was mostly applied by the Stug units themselves.
Enlighten me PK; did the concrete help?
Help against explosive devices ( hollow charge, satchel charge, bazooka ) because the concrete absorbed a big part of the blast, but it have little effect against hard core armor piercing ammunition.
Zimmerit on Brumbär assault vehicle.
it was against AP, those tests showed a negative effect.
here´s some other alternative protection.
Hello.
StuG IV with Zimmerit Anti-Magnetic Coating and frontal Zementpanzerung.
Note the StG44 in the MG Mounting.
StuG IV with Waffle Zimmerit Pattern
Note that the side armor of the fighting compartement has a 30-45cm thick cement side.// CZ April/Mai 1945
The same vehicle - waffle pattern.
Above and on the side of the cement armor [side of the fighting compartement], there are again steel platings [Schürzen]
StuG III Ausf. G [late serie] with Waffle Pattern and Shark Mouth
I still don’t understand, why they applied Zimmerit to the mudgears 
I don’t excactly know the name of this pattern, but it is also some sort of waffle pattern.
PS: I got some more pictures and informations about the ‘specially armored’ StuG’s - i will post that later, got no time right now 
it was against AP, those tests showed a negative effect.
here´s some other alternative protection.
Yes it was designed against Armor piercing ammo, but didnt work very well. In the other hand the sand used in the concrete is effective against high explosive and specially sucking out the chemical energy of the hollow charge projectiles ( panzerfaust, bazooka) as I ve mentiones earlier.
Good pictures there Splinter 54 !! 
Any other nations attempting anything like the Zimmerit?
Sure, the U.S.A, and the USMC specially, the japaneses had a lot of magnetic mines.
The picture here:
http://www.ww2incolor.com/forum/showthread.php?t=1962&page=13
I heard from a japanese friend who was a high-schooler during the war that
“when enemy tanks come, stick wet mud in their veiwholes, when you cant get mud, make some with yurin. Then, stick a Mag mine on the “blind” sherman and run away.”.
Thats how desperate Japan was. Oops. Offtopic,
Interesting photo. I like to know if these Americans were just posing on this captured vehicle? or if it was put into service as a tank destroyer?
This vehicle was captured and indeed put in action by troops of the US 104th Infantry Division.
This is not a StuG IV though but one of latest production type of the StuG III, Ausf. G.
Only few vehicles were supplied with a concrete covering that thick.
The loaders hatch has the remotely operated MG mounting fitted.
I have a chunk I pulled off a Stug 3.
It is a thick plasterlike substance.
There are hairs of some sort mixed in it.
A common practice with old plasterers.