Stability and deposition tendency of colloidal wood resin

The influence of the chemical composition of dispersed wood resin obtained from Norway spruce and Scots pine on its colloidal stability and deposition tendency was studied. The ability of dissolved glucomannans to stabilise colloidal resin against aggregation with simple electrolytes was also examined. Free fatty acids increased the stability of wood resin against aggregation at pH 5. At pH 8 no significant differences in the stability between different compositions were found, except for the dispersion of resin from pine heartwood, which was considerably more stable against NaCl additions than other dispersions. Different preparations of glucomannans were shown to be effective stabilisers of colloidal wood resin against aggregation as well as deposition (at pH 5). Additions of free fatty acids increased the deposition tendency at pH 5, but decreased the deposition tendency at pH 8, when CaCl2 was not present in the dispersions. The addition of CaCl2 increased the amount of deposit both at pH 5 and pH 8.