Why sometimes the interior of my models gets material instead of the default backface?

[DaveR]

Whats is happening with the texture in components?

Hard to tell but chack to see if the components have been scaled without scaling their definitions. Right click on the component and look for Scale Definition. If it’s black instead of gray, the component’s definition eeds to be updated. Check at all levels of nesting. Make sure you are applying textures to faces and not component containers.