Livos Lady, what is a certified product, regarding treatment for cutting boards? I am only aware of certifications from private labs, many of them owned by the people getting their product certified. For example, I have associates who own products that were “certified” by official sounding associations like the Washington Dentists Association, which their business owned.
What is a food safe finish is a long running argument on woodworking forums. In the end, it’s pretty much accepted any common finish can be used as food safe, once hardened or dried, if applicable.
In many instances, non hardened are superior to hardening finishes. Not because they wear better, but because they are easy to maintain and remain pliable. Mineral oil is the commonly accepted finish for butcher blocks for that reason.
As previously discussed, a hardening oil, like pure tung oil or linseed oil, once hardened, just as with a poly finish, isn’t easy to “touch up” or maintain. They seal the wood, so future applications are just surface building and fill only the new cuts.
A cutting board can be used immediately after applying a non-hardening oil, though it’s always a good idea to allow it time to soak in, rather wasting it by wiping it off. The oil will swell the wood grain, which is why mineral oil can make cracks and splits in dried cutting boards disappear.