Yes, you can clean a junk knife, but the process may vary depending on the level of rust, grime, or damage on the knife. If the knife is severely damaged, it might not be salvageable, but if it's just dirty or rusty, you can try the following steps:
Safety first: Before handling the knife, ensure you take appropriate safety precautions. Wear gloves to protect your hands and be careful not to cut yourself during the cleaning process.
Remove loose debris: Use a soft brush or cloth to remove any loose dirt, food particles, or debris from the knife. Be gentle, so you don't scratch the blade or hurt yourself.
Soak in warm, soapy water: Fill a sink or container with warm water and a few drops of dish soap. Submerge the knife in the soapy water and let it soak for about 10-15 minutes. This will help to loosen dirt and grime.
Scrub with a soft sponge or brush: After soaking, use a soft sponge or brush to gently scrub the knife, paying special attention to any stubborn stains or rust spots. Avoid using abrasive pads or steel wool as they can scratch the knife's surface.
Rinse thoroughly: Once you've cleaned the knife, rinse it thoroughly with clean water to remove any remaining soap residue.
Dry immediately: To prevent further rusting, dry the knife immediately with a clean, dry cloth.
Remove rust: If there are rust spots that persist after cleaning, you can try removing them using a mixture of baking soda and water. Create a paste by mixing baking soda with a little water and apply it to the rust spots. Let it sit for a few minutes, then scrub gently with a soft sponge or cloth until the rust is removed.
Lubricate the blade: To protect the knife from future rusting, you can apply a small amount of food-grade mineral oil or knife lubricant to the blade after cleaning and drying. This will help create a barrier against moisture.
Keep in mind that the above steps are intended for cleaning a regular kitchen knife or one that is made of stainless steel. If you have a high-quality knife or one with special coatings, you may want to follow the manufacturer's instructions or seek professional help for cleaning and maintenance. Additionally, if the knife is in very poor condition or if you're unsure about cleaning it yourself, it's better to consult with a professional knife sharpener or restorer.