Hi, I am a healthcare worker and need some either black or navy trousers for work. I need to look relatively smart, but also do a lot of moving and handling, and need to be able to wash clothes at 60 degrees. I was thinking of linen smart cargos, but think they'll look creased and not be able to wash at 60? I'm confused as to whether cotton or viscose are a good idea. Advice much appreciated.