Wax and oil polish on wood Wood countertops are frequently sealed, when a non-hardening, food-safe finish is desired, with some magic cocktail of waxes and oils. Typical components might include mineral oil, beeswax, and carnauba wax, mixed in some unspecified ratio and then sold at premium prices.

Not being content paying for a bottle of magic goo, I'm seeking a scientific understanding of how these products actually work.

These products claim to (over time) build a coating of wax on the surface which is more durable than simply mineral oil would be. If the product is a mixture of oil and wax which is quite thin, how can it build a layer of wax on the surface of the wood with repeated applications? Does the wood selectively absorb the oils? When subsequent applications are made, are the thinner oils able to diffuse through whatever wax has built on the surface?

What are the relevant concepts in play here, and in what directions might I research to gain a deeper understanding?
Mineral oil serially penetrates the wood to render its surface hydrophobic.  Nothing eats mineral oil and it does not easily oxidize (go rancid).  It is also the solvent vehicle to transport beeswax (plasticizer, compatibilizer, internal soft sealant) and the hard wax surface sealant. Nothing polymerizes (re linseed or tung oil) or chemically bonds to the wood.  All three are FDA GRAS.

Like dissolves like.  While the surface will be sealed against polar materials and provide no food for bacteria and fungi of itself (and absence of water is a good biostat), it can imbibe fats and oils.  Butcher block surfaces and such are best made of dense oily woods that are naturally sealed against water.  Top them off.  Lignin is a fair antibacterial and antifungal agent.  Polyethylene cutting boards have higher sustained levels of viable bugs than do wood cutting boards.

http://faculty.vetmed.ucdavis.edu/faculty/docliver/Research/cuttingboard.htm