The mutual interaction between cellulose and plastics has led in recent years to more and more complicated and improved products capable of capturing an extensive share in the paper, board and packaging industry. In most finishing processes, whether they are concerned with the substance of the paper or its surface properties, the maintenance of the morphological structure of cellulose is of decisive importance. This is because the features associated with this structure, especially those of sheet formation and in contrast to synthetic finishing materials, have an enormous influence upon the combined technological properties of the finished product. Indeed, various cellulose derivatives and modified celluloses are known that would achieve the properties obtained when synthetics are added for finishing purposes, but they have the disadvantage in most cases that the fibre structure of cellulose is lost on modification. Therefore, it is not surprising that most composite paper and cellulose products, apart from a few products used mainly in the textile industry, represent an aggregate of the fibre and finishing material.