Removing a plaster stain

[Alexis]

My husband was using plaster of Paris to mend something and wiped his hands on his jeans and then sat in his black leather chair.

There are now streaks of white on the seat.

I have tried vinegar and leather cleaner. Any suggestions?

[home improvement guy]

Plaster of Paris dries, hardens and is tough to remove. Since vinegar and leather cleaner have not worked for you, it is time to ask our readers to weigh in.