A cheap way to keep carbon steel knives and axes lubricated and rust-free is to use common store-bought Mineral Oil or Petroleum Jelly. Mineral Oil is particularly suited to knives because it is safe to ingest while also being odor-free and taste-free.
For axes, try Petroleum Jelly. It has a thicker consistency and sticks to the metal axe head better. Axes generally aren't used for food prep, so taste and edibility are not an issue, making petroleum jelly the better choice. Be sure to wipe off any excess jelly before putting your axe inside your pack, or else a lot of your other gear will get lubricated too!
Mineral Oil and Petroleum Jelly can also be used in other ways for bushcrafting. Petroleum Jelly combined with cotton balls makes a great tinder that's easily ignited with the spark of a firesteel, and Mineral Oil can be used to lubricate moving parts on liquid gas backpacking stoves like the MSR Whisperlite, XGK, etc.
Editor's note: I'm a city girl compared to Jason and Dave and I had never heard of using Petroleum Jelly to start a fire until I edited this article. Over Memorial Day I had some friends over and we decided to have a bonfire. I brought out the cotton balls, Petroleum Jelly, and my Mora Fire-Knife. My friends were skeptical, but humored me. With just one spark from the Mora the cotton ball caught fire and we had our bonfire! I was impressed with how well this worked and my friends were amazed at my new knowledge...now I'll be the one to start our bonfires! -Leah
About the author
Jason Schwartz is the founder and senior editor of Rocky Mountain Bushcraft. He is a former Red Cross certified Wilderness & Remote First Aid Instructor, and has taught bushcraft and wilderness survival techniques to the Boy Scouts of America, interned with the US Forest Service, and studied wilderness survival, forestry and wildland firefighting at Colorado Mountain College in Leadville, Colorado. Jason has also written for magazines such as The New Pioneer and Backpacker, including writing the "Tinder Finder" portion of Backpacker's "Complete Guide to Fire," which won a 2015 National Magazine Award (NMA). Email him at rockymountainbushcraft @ hotmail.com (without spaces)