Mirror with a texture problem.

I read the mirror example for creating a girls head and applied that to another one of my models. The model subsurfaces just fine but when I turn on the ‘set smooth’ the 2 different halfs I combined into one have a deformed line down the middle of a darker shade of the color that I can’t make dissappear. I would assume it’s because the model isn’t merged together correctly but don’t understand what I need to do to fix that problem.

It sounds like a normals problem from here. You can (almost always) fix this simply by entering edit mode, selecting all verts then hitting Ctrl-N for calculate all normals outside. Ctrl-Shift-N calculates them all inside.

If they’re not merged properly, you can either select them all then hit the w key then 6 (above y, not num-keypad) for Remove all Doubles, if some verts are too far apart to merge, you can carefully make the Limit value in the MeshTools tab of the button window EDIT: larger. - you could also hit the “Rem Doubl” button in this same panel instead of w then 6.