Problem scenario
You have been reading The Declaration of Independence: The Evolution of the Text by Julian P. Boyd. The color photographs of the drafts of the Declaration of Independence show a brown ink. Why did Thomas Jefferson choose a brown ink?
Solution
He did not use brown ink; he used black ink. Over time with air, the color of the writing turns to a brownish appearance on the original pages (according to the introduction of American Scripture: Making the Declaration of Independence by Pauline Maier).