I have made quite a few trivets over the years. Almost always in hardwood although did do a few in aromatic cedar. For a finish, I dipped them in mineral oil, then let them drip dry. When completely dry, I buffed them with a brown paper bag to give them a sheen. I have one on my table that has been in use for over 10 yrs with no problem. I found out however, that the ones I gifted tend to get hung on the wall rather than used.