At the class reunion, I signed my name on my clothes, but they were dirty and dirty. How to wash dirty things, but the signature is clear?
That depends on what pen you use. If it is a black signature pen, don't worry at all, no detergent can wash it off!
If it is a blue ink pen, it is not easy to wash it off as long as it is rubbed hard without washing powder or detergent. The suggestion is to soak it in water and wash it clean. It's okay.