White numna sweat stains

[intothegreek]

Some lovely specimen has "borrowed" my daughters brand spanking new white numna and left it covered in sweat, now it's stained deep brown at the saddle contact points. Any tips to get this out. I've soaked it in a bit of bleach and bio gel, it's now baking in the sun but still looks terrible. TIA

I wash ours in the machine. Sounds like dye from the saddle leather rather than sweat.