(Blender) Differences between 'gray' and 'black' surfaces

[Lonecat Nekophrodite]

What are the differences between 'gray' and 'black' model surface? in the same model made based upon existing ones but heavily modified to gain desired sizes and shapes. Several mesh tools are used. one of commonly used command is 'Make Edge/ Face' (out of existing nodes (vertices) and edges). There are moments that it gives out gray surface, yet there's instance that 'black' surface is generated instead

^ This one is heavily modified USS Monitor (Civ5 Union Ironclad, available via Civ5 Unit Conversion Master for Civ6) with Civ6 Destroyer props and shafts. not finished though... basicaly a WIP.
See. there are 'black' surfaces amongs gray ones.
1. How did the Black surface generated?
2. Does it affects skinnings and texture painting later on
3. if so how to fix it?

 

[MightyToad]

1. How did the Black surface generated?
2. Does it affects skinnings and texture painting later on
3. if so how to fix it?

If it is a new face that you added on to the mesh it won't have a UV assigned to it yet. It would appear black or white in texture view mode. Press U to unwrap, and arrange it on your texture map.

If you are in solid view mode the face probable has a different material, or several assigned to it. One of them being black or something.

 

[Deliverator]

The Black surfaces could be because the faces normals are in the wrong direction. You might need to Flip Normals on the black faces. It is possible to display lines for face normals to help diagnose this.

 

[Lonecat Nekophrodite]

The Black surfaces could be because the faces normals are in the wrong direction. You might need to Flip Normals on the black faces. It is possible to display lines for face normals to help diagnose this.

So how to flip normals on black faces?

 

[Lonecat Nekophrodite]

This is what i've got now.

A finished Ironclad Battleship. (loosedly based on a combination of HMS Collingwood, HMS Devastation and Prussian 'Armored Frigates' launched shortly earlier.
But i don't know where the lines on face normals showns up but do you think it this one is good enough to add bones for each of gun barrels and rigging turret and prop animations yet? will it displays correctly? And the latest addition I must admit. is Minas Gerais evacuation boats and associating cranes. Is it possible to merge Minas Gerais materials (including Base and Normal textures of loaned meshes) into a new UV texture file set?