In the manufacture of pulp and paper it is essential that pulpwood bolts be free of bark and it is important to facilitate the barking of pulpwood for decreasing the pulping cost.
For that purpose, the method of putting the chemicals into a tree has been reported to be of some effective.
Akamatsu (pinus densiflora) was used as the experimental tree and Sodium arsenite was applied to a ring-barked part.
Sodium arsenite proved to be the most effective chemical for facilitating removal of bark.
The chemicals went up all right with the sap flow and the withering phenomena seen after applying the chemicals into the tree extented downwards from the needles of 1st whorled branch, the top of stem, to bottom.
The experimental results are shown Table 1, 2 and Fig. 1-8.
June and July and possibly the first past of August were found to be the best months for application of chemicals in order to render the bark easy to peel in the Aufumn of the year of treatment.
After three months for application of chemicals the bark was easily removed, but after one or two months for application of chemicals the bark was not easily separeted from the wood and sometimes becomes difficult be remove.
The physiological means of chemical peeling is to perfectly killing the cambium region of the tree. I made clear this aspect by the microphotograph. For the purpose, the 40 per cent sodium arsenite solution was the most effective chemicals.