Each premium tissue product is designed to satisfy the requirements of its target market. Worldwide, tissue product products and characteristics can vary quite substantially, however common is a requirement for a high degree of softness at a given strength and bulk. These three requirements are not independent, they are related to each other. Besides these, other properties can be required such as absorption (total as well as dynamic), a degree of wet strength, appearance, etc.
In recent years, the use of hardwood pulps (principally eucalyptus) in tissue has increased, the positive effects on softness and bulk are well known. Furthermore, the tissue maker exploits the price differential between hardwood and softwood pulps to minimize the cost of the furnish and therefore the tissue product, assuming that the manufacturing efficiencies in papermaking and converting are maintained at good levels.
The high quality Canfor softwood pulps have a high unrefined breaking length, long and slender fibres (a high fibre length but with a low coarseness) that allow the tissue maker to optimize its furnish and obtain the highest final tissue product quality, but also with good efficiency on the paper machine and in converting.
Manufacturing efficiencies are part of the total cost of the finished tissue product, in this category there are factors such as energy consumption (drying), overall equipment efficiency (OEE), finishing curves (strength degradation in converting) etc. As the fibre is the highest cost item in a tissue product, reducing its cost has a high priority. Also, good pulp preparation is very important for the end result. As refining affects some important tissue properties negatively (bulk, softness) and consumes energy, it should be minimized, and the refining conditions should be optimal. Without going into detail, the hardwood portion of the furnish should not be refined, or refined as little as possible, while the softwood portion should be refined separately and under optimal conditions. Using a proper pulp preparation strategy, freeness at the headbox can be optimized, which can reduce energy (drying) cost while having a positive effect on softness.
A mill trial with Canfor’s pulp is ideally prepared well in advance, whereby pulp and tissue products have been round robin tested by both the mill’s lab and Canfor Pulp Innovation. When the test results are coherent and understood, objectives are agreed to prior to the mill trial. In some cases, Canfor Pulp Innovation supports a trial with technicians and testing equipment.