I think you're saying 'neutral' there. Here's some natural wood coatings I've used: Pure linseed oil, Tung oil, walnut oil, or mineral oil. All have different viscosities and will dry at different rates.
Or, you can just use some beeswax. Shellac is another option. Without stripping the entire boards, it will be difficult to maintain a consistent finish.
Search for the Mar-K 10-15 year study on this topic. Hope this helps.
Brad
