Old millboard contains sufficient iron impurities to promote the formation of sulfuric acid due to the presence of sulfur dioxide in the atmosphere, much in the same manner as in paper, although at a much slower rate. Millboard, furthermore, often suffers from an additional defect from the point of view of the bookbinder, namely, excessive lamination stemming from the pressure used in calendering. This excessive lamination can cause the corners of the boards to be subject to splitting and mashing.
Rope fiber millboards were first produced in the late 17th century, but they were not in general use until perhaps the first and possibly the second decade of the 18th century, and even then only in the superior grades of binding. The cheaper machine-made boards were in use as early as the 19th century. Millboard was used continuously until the Second World War in the better grades of binding. (82 , 161 , 198 , 236 , 335 )