The same gram weight of Kraft paper may have different hardness paper properties, which is mainly due to the original solid of the pulp. As we all know, the raw material of Kraft paper is plant fiber, the trunk part of the tree has the highest content of wood fiber, so the production of Kraft paper hardness is the highest, that is, we often say pure wood pulp Kraft paper.
However, recycled Kraft paper will add bark, rags and other materials, hardness will be lacking. So the hardness of Kraft paper depends on the content of wood fiber, the higher the content of the paper hardness is better. Different varieties of tree fiber content is not the same, different areas of the tree fiber content is also different, so the pulp produced after the production of Kraft paper hardness will be different. To reach the same hardness, it is best to use the same batch of Kraft paper.
