I have a question that seems to be unanswered for some time. As most of you know, I am scratch building a Panzer IV J. Well in the proccess I am also scratch building the Zimmerite in very thin sheets of brass. My question to you is when you have a large piece of brass that needs to be glued into place on your model how do you or what is the best way to keep in glued to your model? What I am trying so tell you is the front part of my Panzer IV J will have Zimmerite on it and for this part I have a sheet of brass that I just scratch built and is ready to be glued into place. I tried, just as a test piece, glueing this piece to a sheet of styrene but once it dried the brass popped off the plastic and the glue was easily cleaned off the brass in a matter of seconds. Can someone please tell me how do I prevent this from happening again?

Brass to plastic calls for super glue or epoxy. Superglue does not have a lot of strength when pulled from the side but great strength when pulled from the perpendicular. So you could pop something off with a lever, but absent that, the attachment would be quite strong. If you bent the plastic at all, this would weaken the bond. I'd score the plastic a bit, rough it up with course sandpaper before glue the parts together. Epoxy has a bit more lateral strength and I'd again score the plastic to give it more bite.

Thank you once again. I will try out your advice.

Plasticard/brass gluing with superglue on large areas is not the best in terms of strenght and uniformity. I'd prefer to use epoxy. In my view it is better to use copper, if possible, instead of brass to get the best results with superglue. I prefer copper because it is more workable than brass.
Anyway I've got a question for you: why you're going to glue a metal sheet on plasticard? Wouldn't be easy to do it all using either plasticard, in such a case you can use standard plastic glue to do the job, or brass/copper that is may be harder to work with, but you can solder it having very strong strong joints?
Sorry if this can look a bit of a provocation, but when I scratchbuild I try to have the most "consistent" approach to materials.
Ciao
Fabio