It's not necessarily a bad idea for use building a rack but I would recommend putting a finish on the wood for sanitary purposes. Using unfinished wood prevents you from washing down the rack and if you ever get a mite infestation, it will be a nightmare with mites forming nests in the cracks and crevices of the wood. After putting a finish on the wood, you would need to let it cure for a few weeks before putting it to use.