I treated stains on some vintage formal white linen napkins with bleach, and then washed them alone with some Tide. There are initials embroidered on the napkins in white thread. The white embroidery has turned blue in varying degrees. I have applied straight vinegar with no result. Can I do anything to turn the embroidery back to white?
I’m not sure from your description exactly how you treated the napkins and whether the initials were also involved. I suspect that you used a concentrate/full-strength bleach solution and that the initials are of a different fiber type than the linen napkins. If your bleach was too concentrated, then it could react with fluorescent whitening agents that are probably present in the thread. This changes the chemical composition and can result in a blue/purple hue. Unfortunately this is not reversible. Your vinegar post treatment would have been my suggested “fix.”