Sample handling

Some hints regarding how to handle the pulp samples.

Sub-sampling. The pulp sample to be analyzed typically has to be sub-sampled to determine the weight and viscosity. Never cut the sample using scissors, since that might affect the viscosity of the sample. The cutting will introduce shorter fibers which might reduce the viscosity. Instead, always tear the sample by hand in order to minimize the amount of artificially disrupted fibers in the sample to be analyzed.

Reduce oxidation. In order to reduce the oxidation of the sample in the CED solution, the air in the bottle should be evacuated. Use a soft bottle with an airtight cap. Squeeze the bottle until all air is removed and tighten the cap.

Time to analysis. The analysis of the prepared sample should be performed as soon as possible after the sample preparation is completed. This is important since the viscosity of the prepared sample is gradually reduced during storage 1. If a certain time is required after the sample prep is completed, all samples should preferentially be analyzed given the same delay in order to be possible to compare.

Control samples. Some labs have reported lifetimes of control samples in the range of 1-2 years instead of the more standard 3-6 months. This can of course be an effect of the nature of the control samples themselves, but also of the handling of the control samples. Keeping the control sample in a dark, dry, refrigerated and airtight environment seems to increase the lifetime of the sample.

The ViscLab software contains support for using 0.5 M CED solution as a control sample. While this does not include the sample preparation procedure as when using a pulp control sample, iit is a quick method to determine the status of the most important parameters.

1 Wood Sci. Technol., 2004, 38, 139-148