I'm intending on building a few shelves from scratch, including chopping down the wood, and then treating it. With my budget tightening up, what are some easy to access methods of harvesting oils from plants or other places? Fish oil won't do. I'd rather not have a fish smell coming from the furniture.
Normally, oils are extracted from vegetable material using various combinations of temperature and pressure during a distillation process.
Oily materials can be squeezed directly. A Walnut can be rubbed vigorously on a walnut wood surface and the oil from the walnut will infuse into the wood.
Some materials must be put into a solution to dissolve the oils in the material and the solution is then distilled to separate the desireable oil from the more volatile solvent. Recovering the solvent for re-use is part of a continuous extraction process otherwise it is discarded ($). The solvent cannot be water as it won't dissolve the oils in the material.