A greased paper window is a very inexpensive window made of paper coated in grease. The application of grease fills the gaps between paper fibers, reducing the amount of light lost to scattering, and thereby affording a somewhat diffuse light source which can still prevent insects and other animals from entering a structure. Greased paper windows were often used by American pioneers of the early 1800s and other itinerant peoples, in lieu of relatively expensive traditional glass windows. Laura Ingalls Wilder recalls living in a home with a greased paper window in her 1937 children's novel, On the Banks of Plum Creek.