Any of the cereal straws may be used to make paper pulp, and although wheat is the one most often employed, barley, rye, oat and rice straws are also used. There is probably no significant difference in the grade of pulp obtained from them. Even though the supply of straw runs into the millions of tons, it has not found very wide application in the manufacture of paper and board, except for its widespread use during the Second World War. The cereals are all annual crops and the bulk of the supply for a year's production of a paper mill would have to be gathered within a very brief period, which means that the mill would have to have a very large capacity for baled straw. In addition, unless the mill has means to protect the straw from the weather, deterioration might take place. In most cases the pulp mills are not located near the areas where the straw is produced; therefore, transportation costs would have to be considered. This is particularly significant since the bulk of straw is so much greater than that of wood, which means that the amount of paper pulp obtainable from a given digester capacity is relatively low.
Chemical tests for determining the presence of straw in paper include the aniline sulfate test, which gives a pink stain. (143 , 198 )