We made a semi commercial grinding test of some soft woods grown in the Shizuoka district. The woods used are as follows :
Pines (Akamatsu & Himekomatsu), Firs (Sirabe & Momi), Spruce (Tohi), Hemlock (Kometsuga), Larch (Karamatsu) and Chamaecyparis (Hinoki).
The grinding conditions : 400 Hp 3 pocket grinder, natural sandstone, 250r.p.m.press 301bs, pit temp., 70°C, Burr ; spiral 8 cut I 1/2 in. lead.
The characteristics of pulping these woods are as follows :
Akamatsu ; Refined pulp yield is high. Energy consumption is comparatively low.The pulp is short fibred, bursting ratio 0.9, whiteness 66, grayish.
Himekomatsu ; A.P.M.W. screen waste and white water loss are much, so the refined pulp yield is very low. The pulp is long fibred, bursting ratio 0.9 whiteness 70, but very yellowish. The fatal defect Is high pitch content (about 30%).
Momi ; Refined pulp yield is a little lower. The pulp is short fibred, bursting ratio 1.0, whiteness 64, a little reddish.
Shirabe ; A.P.M.W. screen waste is much. Refined pulp yield is low. Energy consumption is low. The pulp is long fibred, bursting ratio 1.1, whiteness 70.5.
Tohi ; A.P.M.W. screen waste is much. Refined pulp yield is low. The pulp is long and soft fibred, bursting ratio 1.4, whiteness 68, a little reddish.
Kometsuga ; White water loss great. Refined pulp yield is low. The pulp is a little short fibred, bursting ratio 0.6, whiteness 60, very reddish.
Karamatsu ; Refined pulp yield is low. Energy consumption is high. The pulp is short fibred, low freened, bursting ratio 0.8, whiteness 48, dirty.
Hinoki ; Refined pulp yield is a little lower. Energy consumption is high. The pulp is short and fine fibred, pulp sheet is dense, bursting ratio 1.1, whiteness 62.5, reddish.