Read the text and choose the correct answer.
1. As you travel through the countryside, you'll often see old barns. These barns remind us of the early days of farming and the importance of machines in our world. Many old barns share a common feature: they are painted red.
2. Today, red barns are a tradition. When a farmer builds a new barn, they often choose to paint it "barn red" to resemble the red barns from the past. But how did this tradition start? Initially, the first barns in America were not red. In fact, they were left unpainted because early farmers in New England had little time and money for painting. However, the severe weather caused barns to decay over time and need repairs. To protect their barns, farmers looked for ways to protect them from the elements.
3. They discovered that treating wooden barns with linseed oil, milk, and lime created a strong coating that dried quickly. To prevent mold and moss from growing on the barns and causing decay, farmers added iron oxide, or rust, to the paint mixture. Rust was abundant on farms and provided effective protection. The homemade paint made from linseed oil, milk, lime, and rust resulted in sturdy paint that dried to dark orange or burnt red. As many farmhouses were white, the red barns stood out and became fashionable.
4. Over time, better paints became available. Even though farmers no longer needed to make their own paint, many continued the tradition of painting their barns red to honor the history and charm of these iconic structures.
-> Farmers mixed some materials to make a coating EXCEPT ______________