Michael Bushman wrote:Most of what people know about finishing wood is myth.
Michael Bushman wrote:...Linseed oil is not as waterproof as tung oil but neither are as waterproof as polyurethane.
Michael Bushman wrote:...Many "food safe" and "salad bowl" finishes are in fact polyurethane with additional thinning agents...
If wood will be in contact with moisture, the two best ways to keep it from rotting are to either leave it all natural so that the water it absorbs can evaporate or finish both sides with a film finish like polyurethane or varnish and ESPECIALLY the end grain.
Michael Bushman wrote:Varnish is used on boats because it used to be the best at surviving in the sun and it is flexible so that as the wood expands and contracts with changes in moisture, it didn't crack. Its a PIA to apply, its slow drying time means dust and such has lots of time to settle into your finish...True shellac and lacquer create a single layer as their solvents dissolve the previous layer and bond chemically and so no sanding is needed between coats.