14 BULLETIN 1296, U. S. DEPARTMENT OF AGRICULTURE 
PULPING CHARACTERISTICS OF DECAYED WOOD 
PHYSICAL PROPERTIES OF MECHANICAL PULP MADE FROM SOUND 
AND DECAYED SPRUCE 
CHARACTER OF WOOD USED 
In order to demonstrate the large losses sustained and the difficul- 
ties encountered in the use of decayed wood, comparative grinder 
runs were made on sound and on decayed spruce wood at one of the 
cooperating mills. 
The sound wood, sample 1 (PL IX, fig. 1), was 12-foot Wisconsin 
spruce taken direct from a car which had just been received at the 
mill. 
The decayed wood, sample 2546 (PI. IX, fig. 2), represented 
ordinary mill-run Minnesota spruce, approximately 3 years old. It 
had been stored in 8-foot lengths directly on the ground, in close 
ricks, in a solid mass of several thousand cords. (See PI. VI, fig. 3.) 
The logs used for the grinder runs were selected from the lower half 
of the piles. They were representative of severely infected material, 
but no wood was so badly decayed that it would have been rejected by 
the mill. 
The principal fungi rotting the wood, in the order of their frequency, 
were Fomes roseus, Stereum sanguinolentum, Polystictus abietinus, 
Lenzites sepiaria, and Trametes pini. A tally of 184 of the 250 sticks 
showed 75 sticks infected with the first fungus, 59 with the second, 
28 with the third, 16 with the fourth, and 6 with the fifth. Fomes 
roseus was represented in the living tree to a certain extent as a heart- 
rotting organism, but most of the rot probably developed in the pile. 
Trametes pini was undoubtedly introduced altogether as heart rot from 
the standing tree. All the other fungi developed from infections sub- 
sequent to cutting. Of these, Lenzites sepiaria readily attacks both 
heartwood and sapwood; Stereum sanguinolentum and Polystictus 
abietinus attack the sapwood principally. 
METHOD OF PREPARATION 
Approximately 5 cords each of infected and sound wood were 
selected, weighed, and ricked. This material was then sampled by 
cutting disks 6 inches thick for specific gravity determinations (PL 
IX, fig. 3) and thinner disks for moisture determinations. The 
moisture disks were weighed directly after cutting, wrapped in paper 
to prevent loss of small particles of bark and wood, and sent by 
express to the laboratory for the actual moisture determination. 
Fourteen of the sound and 26 of the infected sticks were sampled in 
this manner. 
After being sampled the logs were dumped into the hot pond and 
cut into 2-foot bolts, all the odds and ends being collected and 
weighed and this weight deducted from the weight of the rough wood. 
The 2-foot bolts were barked on knife barkers and corded in cord 
ricks. 
Preliminary to grinding, the ground-wood chest was run dry and 
washed out. Two 3-pocket grinders were used, with a pressure of 35 
pounds per square inch on the piston heads and an average speed of 
220 revolutions per minute. The stones were sharpened equally for 
