Floor board and method for manufacturing such floor boards

A floor board comprising a substrate having side edges and a decorative surface layer applied to said substrate, said substrate comprising MDF or HDF material at at least one of said side edges,

• wherein said decorative surface layer and a surface of the floor board opposite thereto form surfaces of the floor board;
• wherein said at least one side edge is treated with an impregnation agent;
• said at least one side edge together with a side edge opposite thereto forming a first pair of opposite side edges of said substrate;
• wherein said floor board further comprises a second pair of opposite side edges;
• and
• wherein said MDF/HDF material comprises higher density regions near to one or both of said surfaces.