By: Wes Wallace
She recommends looking at the type of paper. High cotton or rag papers was popular before 1850. She says you can hold it up to the light to check for horizontal and vertical lines called 'chain and wire lines.' Examining it for watermarks and certain inks also help too. "A popular ink is the iron gall ink, which is very acidic and often eats holes in paper," explains Dr. Speer.