Why have blue plasters?

Question

A blue plaster is quickly detectable visually. There is almost no food that is blue by nature. Should a blue plaster end up in the food chain, it can be seen and removed quickly thanks to its blue colour.

Accepted Answer

A blue plaster is quickly detectable visually. There is almost no food that is blue by nature. Should a blue plaster end up in the food chain, it can be seen and removed quickly thanks to its blue colour.