I was taught to use a much water as humanly possible to wash it off. Bear in mind that it is in the skin and clothes, so you will need to keep on rinsing it to try to negate the action of the acid in the skin. The clingfilm is to prevent dirt and bacteria getting to the damaged skin after it's been thoroughly rinsed. And in this weather, do not forget the risk of using so much water that the core body temperature gets dangerously cold - keep the rest of the body covered. Finally, treat for shock while you are waiting for paramedics.
I was taught to use a much water as humanly possible to wash it off. Bear in mind that it is in the skin and clothes, so you will need to keep on rinsing it to try to negate the action of the acid in the skin. The clingfilm is to prevent dirt and bacteria getting to the damaged skin after it's been thoroughly rinsed. And in this weather, do not forget the risk of using so much water that the core body temperature gets dangerously cold - keep the rest of the body covered. Finally, treat for shock while you are waiting for paramedics.