I Separated An Object from Others - It Still Has Textures From Them

EDIT: found ok solution - see note below my main text.

Original Question: I have a project with a little town consisting of many buildings. I merged them together as one object for easy posing. Now, I want to change the roof color on one building. I separated that one building to be its own object again (P to seParate) but now if I select that lone building and open the materials tab, there are hundreds of materials that show up. I can’t find the material that is the roof that I want. So, basically, I need to know how to find one discreet object’s material and jump to it in the materials panel. Is there a way to select a face or vertex in edit mode, and then hit some button and have the materials panel auto-open only the material(s) for those faces or verticies? It seems that if select an object, I should be able to easily see only those materials that are associated with that selection and nothing else. I’ve used Blender for more than 15 years, and I still find this insanely unintuitive and baffling.

EDIT - so it looks like after selecting a face, I can use the “Select” button to pretty much do what I wanted. If this is the best way to do this, then feel free to delete my post.

separate will copy all mat to new ob as I know of!

may be try to make a Vert group before separating should work I guess

or create a new UV map for some faces and assign faces to that new UV map

then when you select you got your faces for new UV map

happy cl

There is also the Materials Utils Specials add-on that has some nice utility functions for dealing with materials https://wiki.blender.org/index.php/Extensions:2.6/Py/Scripts/3D_interaction/Materials_Utils

In particular the Clean Material slots can at least reduce you to the few that that mesh is actually using.