The methods for removing blackened hands caused by walnut skin include: washing with hand soap, white vinegar, soapy water, and wind oil, and leaving it to fade naturally.

1. Washing with hand sanitizer: The reason why walnut skins are dyed is because walnut skins contain a large amount of walnut greeningin, which will oxidize and turn black when it comes into contact with human hands. If you accidentally get walnuts in your life, Skin juice can be washed away with hand soap.

2. White vinegar cleaning: If the walnut peel liquid has been on your hands for a while, it is generally recommended to use vinegar to clean it, because vinegar contains a large amount of acetic acid and has a strong cleaning effect. Can help dilute walnut cingonin.

3. Washing with soapy water: Soapy water is an alkaline liquid, and walnut bark cyanin is acidic. Washing hands with soapy water can neutralize the acid-base stains on the stained area. Apply soap to the stained area, scrub a few times, and then rinse with clean water.

4. Cleaning with Fengyoujing: Fengyoujing is a good organic solvent. When applied on the hands, it can help dissolve the stained parts of walnuts and has a very good cleaning effect. Dip a cotton swab into an appropriate amount of wind oil essence and apply it on the stained hands, then rub your hands and let it sit for a while until the color can be obviously lighter. Finally, use alcohol or gasoline to clean it.

5. Wait for it to fade naturally: Due to the walnut cyanin in the walnut liquid, once it has been oxidized and turned black for a long time, it will be more difficult to clean. If the above methods are used, it will not be able to achieve the goal. To achieve the desired effect, it is generally recommended to let it fall off with the metabolism of the skin over time. These substances are not harmful to the human body.