White Marks on Washing (pic)

[JennyCarrots]

Thrilling thread of the week alert....
I've washed all of the white shirts as usual on a 60 degree wash with soap powder, Oxy whitening powder and fabric softener as I've done for years. They've come out like the picture. I've rewashed without fabric softener and used white vinegar instead but it's made no difference. There's 10 school shirts and 5 of husband's work shirts like this! Any ideas if how to remove the marks and avoid an expensive shipping trip this weekend?

[JennyCarrots]

Stand down. The problem was stuff left in a shirt pocket that melted over the clothes, probably in the dryer.