Being able to put a keen edge on your knife is almost as important as carrying the knife in the first place. Since a dull knife won’t cut very much, every knife owner should have the skills to restore his blade to working order. Using the right sharpening equipment is an important facet of the operation, but once you have the right techniques down, you can literally sharpen your knife on a rock. Why do you think they call them sharpening stones, anyway? Here are three places you can sharpen your blade if you get caught without your usual sharpening equipment.

Car Window: The rough edge of car window can be surprisingly effective as a sharpening surface for knives with softer steel. Use the rounded edge at the top of any vehicle window the same way you’d use a sharpening rod. Drag the knife edge across the abrasive surface in a curving sweep. Make ten to twenty strokes on each side of the blade for light touch-ups. Use more strokes for serious sharpening jobs. Switch windows when you notice that the one you’re using loses abrasion.

Another Knife: If you’re carrying knives of different hardness, the denser steel can act as a honing surface for the blade with softer steel. If the harder knife has a square spine, drag the other knife edge across it. If not, use any other flat part of the harder blade. A

Rounded Smooth Stone: Look for a round, fine-grained stone in a nearby stream. Select one that has a smooth section and seems similar in texture to your normal sharpening stones. Apply some water to the stone and sharpen your knife with little circular strokes, equal numbers for each side of the blade. Rinse your stone often while sharpening to keep the pores open so they continue cutting steel. Strop the blade against leather or rough cloth, and then test the sharpness. Go back to the wet rock for more, if needed.

What unconventional means have you used to sharpen a blade? Let us know in the comments.