<<Disclaimer: Verify this information before applying it to your situation.>> I just spoke with a representative of the Humphrey Charcoal Corp. They have two types of charcoal...both hardwood. The "pure hardwood lump" is 100% wood and contains no additives. the hardwood briquettes contain corn starch as a binder. He does recommend that, just to be safe, we use the pure hardwood version. Happy grilling. Jo