A childhood belief about skin

My mother is a South-African who emigrated to Europe before I was born. As a political activist she always referred to Blacks as "Africans." I was unfamiliar with the term black as a noun rather than an adjective.
When I was five we visited South Africa. On a trip at Kruger Park I encountered a washing area that had a sign that said "Nie vir swartes nie" ("Not for black people"). I assumed that it meant that the washing area was forbidden for people who were, like me, black from playing in the dirt, and was consumed with the thought that I would be arrested for washing there. I also wondered how they expected me to become pink again if I wasn't allowed to wash, and where the washing area for dirty kids was, and whether I would be expelled from the country for putting my muddy feet in the basin.
When my father and mother explained about Apartheid and the meaning of that sign I cried in righteous indignation for hours.