I'm building the excellent Dragon Tiger (late) and have the (also excellent) Atak zimmerit set.

My question is - if i model battle damage to the zimmerit, what colour would be exposed underneath - would it still be dark yellow or would it be hull red? Since i think the zimmeritt was factory applied at this stage of the war, I'm thinking hull red.

Would be grateful if anybody could clarify this issue?

You are right, it would be red primer.

Jesse

This question comes up frequently on modelling boards. There are several different appearances possible regarding damaged zimmerit. This variance is due to the way zimmerit was applied as well as priming and painting practices of the Germans.
Zimmerit was applied in two layers. The first was applied with no little or no pattern. This was then dried by blowtorch and left to cure for 24 hours. The second coat was then applied and the pattern inscribed. The total thickness of the zimmerit after this was in the neighborhood of 10mm. Note that the zimmerit is applied over the primer and before the base coat of dünkelgelb. (source: Tomas Chory, Wehrmacht Heer Camouflage Colors 1939-1945).
When damaged, the zimmerit could chip off revealing either: 1.) The first coat of zimmerit (usually a creamish-gray although initially it was colored with ochre pigment to somewhat resemble dünkelgelb); 2.) The primer if both layers of zimmerit have chipped off; 3.) Bare metal if the damage chips off the zim and primer. Usually this would only be the center of bullet/shot hits or other heavily damaged areas. You could see all of these on the same vehicle, or you could see predominately one or the other because there could be variances in how one or both coats of zim were cured. For example, if you look at the cover art of Dragon's early Panther A, you will see a vehicle with lots of patches of cream/gray areas where only the top layer has chipped off. Squadron's Panther in Action book has a wonderful series of pictures of this very vehicle and there is considerable contrast between the patches and the paint of the vehicle. It appears that it suffered from a poorly applied second coat, or an improperly cured first coat because the chipping is quite pervasive and consistent.
Finally, crews may paint the damaged area. In this case, the chipped areas would be oversprayed in the disruptive colors of the vehicle or even dunkelgelb if factory repair or refitting was done on the vehicle.
Hope this helps!

Thanks Steve, that's a big help and gives me some options to play around with.

Simon