soap flakes

US /ˈsoʊp ˌfleɪks/
UK /ˈsoʊp ˌfleɪks/
"soap flakes" picture
1.

small, thin pieces of soap, used for washing clothes or for making soap solutions

:
She added a handful of soap flakes to the warm water for delicate laundry.
My grandmother always used soap flakes for handwashing.