Art A drawing or painting on brittle yellowing paper may not be an antique. The process that causes aging in works on paper can damage the art in a matter of weeks or months rather than decades. It is the acid in the paper that causes it to gradually discolor yellow or brown with age. If the work on paper is framed properly the process will be slower but never completely stopped. The best way to prevent the discoloration is to use acid free paper and to prevent the paper from contacting other acids.
Paper is made of cellulose which is an vegetable material from cotton, wood or flax.
When cellulose ages it will discolor and become more brittle but the better quality the paper, the more slowly the process will occur. Sizing is the gelatin that seals the paper to make it less absorbant. Cotton also has cellulose but the cotton plant fibers are shorter and the resulting paper is not as strong. Papers such as newsprint, cardboard, or inexpensive drawing paper are made from wood pulp are acidic and will yellow quickly The lignen that holds the wood cells together is very acidic but innexpensive papers are also often sized with acidic sizing. Matboards sometimes have a buffering agent added to counteract the acid bearing lignen in the board.