Around the beginning of the twentieth century, separatist standards, such as the brown paper bag, comb, pencil, and flashlight tests began to be implemented.
Closer inspection revealed that some nails, which were less corroded, were insulated from the copper by brown paper which was trapped under the nail head.
One of the most visible uses for unbleached kraft pulp is to make brown paper shopping bags and wrapping paper where strength is particularly important.