I have a raincoat that I wear when I'm cycling in the rain and it almost covers my knees by not quite so they still get soaked. I was thinking I could lengthen the coat by adding some waterproof fabric along the bottom but I'm not sure what is an appropriate fabric to use and label has faded so I can't tell what this fabric is made from except that it includes nylon. I could use a spray adhesive and/or sew along the existing hem. The coat is grey and blue so I'll probably aim for a dark grey but a close match is not important.