Here is what the wood doctor said about his walnut oil products:
Walnut allergy is elicited by the proteins in the nut, wood and leaves. The walnut oil I use is treated and filtered such that no protein is detectable by the most sensitive methods in my lab (mass spec and colorimetric). I can find no data on cross reactivity between nut allergens. I do not guarantee that there is not risk of allergy, but the risk is as small as I can make it. Moreover, since walnut oil is a drying oil, it is found in the wood as a solid, plastic-like material that is not going to be lost in a liquid form, making any protein residue unavailable for biological interaction.
He buys walnut salad oil that has been filtered and treated[SUP]1[/SUP] to remove the protein that causes the allergic reaction. He feels reasonably confident that the risk of allergic reaction is minimal, but not enough to put his neck on the line. His walnut oil products may be perfectly safe, but I have no way to know for absolutely certain and I suspect that because of his disclaimer, neither does he. His walnut oil products are not the same as other walnut oil products so there is no implied extension that all walnut oil finishes including those made by other companies are just as safe as his for anyone with an allergy to walnuts.
I use walnut salad oil because I agree with the wood doc that it gives a better looking finish than BLO or tung oil. I don't make treenware so my finish is not going to come in contact with food. If I make something that is going to Empty Bowls or given to someone I don't know then I don't use an oil finish.
[SUP]1[/SUP] Probably homogenized which is a process that pressurized a liquid product to 2500 PSI or higher and passes it through a microscopic orifice to break the bonds in long organic chain molecules. This is done in milk to keep the butterfat protein molecules from separating from the whey. Breaking up the protein molecules in walnut oil could possibly prevent the body's immune system from having an allergic reaction. He doesn't say it is heat treated and I doubt that it is beyond pasteurization which involves minimal heating (typically 160° F for about 30 minutes).
