How to remove stains from Karate gi?

[AnnPerkins]

Poor DH took delivery of a new gi yesterday, put it straight in the washing machine as directed and it came out covered in black marks. It's made from extremely stiff cotton canvas and must have got caught up in the door seal and wiped all the gunk and crud off.

Gis are very expensive and DH is gutted. He sprayed it with Vanish and washed it again but it had zero effect. I'm going to leave it soaking in the bath all day with detergent. Any other ideas for getting the stains out?

[JiltedJohnsJulie]

Sunlight? If you can find any that is...

[AnnPerkins]

Yes it's in short supply here today