I've got a 100% acrylic jumper which has developed a musty, damp, unwashed smell that I can't get rid of. It started 2 washes ago and I thought it had just taken too long to dry so threw it back in the machine and made sure it dried quickly, but it still smells. The rest of the load is laundry fresh. I only ever wear the jumper on 'scruffy' days so I'm prepared to bin it but any suggestions on how to get rid of the smell before i do.