As a wood, a walnut log is a sensible alternative for use for a mantelpiece. On the other hand, the natural beauty of this timber complicates finishing a walnut log mantel somewhat. Utilizing wood stain or lacquer on walnut is a mistake, since it disguises what is an already amazing and somewhat expensive choice of wood. Alternatively, you must pick a finish that enhances rather than covers the character of this walnut.
Sand the walnut with fine-grit sandpaper (180-grit to 240-grit). Use a handheld vibrating sander to the horizontal top of the mantel, and an oscillating tool for those corners and edging. In case your pine log mantel has a rounded side, and many do, sand it to prevent flattening it.
Wipe the log down using a tack cloth to remove sawdust, paying particular attention to the corners.
Brush in an oil finish, such as walnut oil, linseed oil or mineral oil. Allow the oil to penetrate overnight, and apply at least one more coat of petroleum subsequently. Employ further coats of petroleum after allowing for proper drying period in case a deeper walnut coloring is wanted. If you don’t want a glossy shine in your log mantelpiece, stop .
Put a glossy shine on the mantelpiece, if wanted. Polish the wood by sanding the oiled surface, lightly and by hand, with an extremely fine-grit sandpaper, for example 600-grit. Wipe the sawdust using a tack cloth.
Buff the log by rubbing it with a fresh washcloth and timber wax.