As for your question about lead being heavy, it's true that lead is a dense metal. However, the amount of lead used in paint was relatively small, so it didn't significantly affect the paint's weight or application. The benefits of lead in paint outweighed the minor inconvenience of its weight for many years. The health risks associated with lead paint, particularly lead poisoning in children, were not fully understood until the mid-20th century. This led to the eventual ban of lead-based paints in many countries, including the United States in 1978.