Mineral oil Brendan! Mineral oil, if consumed in large amounts, is a natural laxative; easy on the stomach. However, if you are just coating the exposed steel in mineral oil and it is consumed, you won't be running to the john every 5 minutes and it will be 100% safe for your children. Hope this helps! Its what I use for my beloved Swamp Rats, and I have yet to see a rust spot or any patina on my blades.