I use Perk by Twin Pines of Maine, along with their product Boost >>>msg
To whiten or brighten items. The items can be soaked for days safely in this solution. I also use their hair product for the doll hair or just shampoo and conditioner. You can also use baby shampoo. I press the clothing with a tiny iron and some steam or dampen the clothing, being careful not to burn with the iron.
You can email me if you need help. Iíve done a whole lot of vintage Barbie/Friends clothing like this. Good Luck!