The grinding of Engelmann spruce for newsprint and magazine quality mechanical pulps

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Material Information

Title:
The grinding of Engelmann spruce for newsprint and magazine quality mechanical pulps
Physical Description:
Unknown
Creator:
Schafer, E. R ( Earl R )
Pew, J. C
Forest Products Laboratory (U.S.)
University of Wisconsin
Publisher:
Dept. of Agriculture, Forest Service, Forest Products Laboratory ( Madison, Wis )
Publication Date:

Record Information

Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 29314718
oclc - 755789756
System ID:
AA00020576:00001

Full Text





TIE[ GIINIDING r IEN6ELMANN SIPIIUCE FCI NEWSPIPINT ANID

MAGAZINE QUALITY MECHANICAL PULIPS

January 1942






















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UNITED STATES DEPARTMENT OF AGRICULTURE
FOREST SERVICE
FOREST PRODUCTS LABORATORY
Madison, Wisconsin
In Cooperation with the Univenrsity of Wisconsin










9LKKNN SPRUCE FOR NEWSPRINT

LLITY MECHANICAL PULPS



SByineer
31FE, Engineer








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14-point diamond burr, and had been in service until the stone
s decidedly dull. The first pair of experiments was made on this
Pressure was adjusted so as to give somewhat above normal energy con-
In the second set of experiments the stone was dressed with a
1/2-inch lead spiral burr and then a 14-point diamond burr, and
ground until the surface was in a stable condition but still quite
e pressure in this case was adjusted so as to give normal or some-
normal energy consumption. Pit temperature, stone immersion, and
y were kept substantially constant in each pair of experiments.
obtained were lapped on the wet machine and samples tested according
d methods-.

Results

The properties of the wood ground, the grinding conditions and pulp
ts are given in table 1. The two species of spruce had about the
ty but the white spruce was considerably drier. Because of the
in diameter it was not possible to charge the pockets in exactly
manner with both species so the actual pressures may have been some-
riance. The runs on the dull stone surface (grinder runs 393 and 39)
somewhat above the normal amount of energy but gave exceptionally
ps, with slightly lower than normal freeness and average fiber
ith a sharp stone (grinder runs 395 and 396) free pulps of standard
'ere produced at rather low energy consumption. The two species
of about equal streng,'th-energy ratios, with both the dull and sharp
aces; therefore, it is concluded that Engelmann spruce and white
about the same density will grind similarly and produce similar pulpit

The properties of the two pulps produced at the lower energy con-
ere so close to that of standard newsprint groundwood that experi-
he making of newsprint paper from them did not seem to be necessary.
produced at the higher energy consumption were of sufficiently high
i consider them suitable for use in groundwood-containing book and
apers although no experiments were made to prove this. These two
also interesting from the standpoint of making a newsprint paper
rom groundwood. Table 2 shows the results of paper machine runs wit:
.t of the Engelmann and white spruce groundwoods and the average of
Snewsprints for comparison. The experimental papers compare quite
the commercial. The bursting and tensile strengths are higher than
*e standard newsprint but the tearing strengths are lower. The cast:
nationss of the experimental papers are appreciably higher than the
indicating there would be less rapidity in absorbing the printing
i the standpoint of machine operation the principal difference as
;o a standard furnish is the necessity of running the machine slower
Sthe lower freeness of the groundwood pulps.

standard testing methods for pulpwood, pulp, stuff, and paper,
Products Laboratory.






























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>as ---- - I I *04 .7I-s6 5500.6
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Table 2.--Newsprint paper composed entirely of Engelmann and white spruce groundwood pulps


-*.... . ,.. ... _, l .. . .. 9 9 t ttlll

Groundwood pulp : :Bursting:Tearing: :
Machine: ---------------------- -. Weight:Thick-:---------------- :Tensile:White- :Castor :Opacity: Ash
run : Species :Grinder:Jordan- : per : ness : Per pound : per : ness : oil :
: ing : ream: : per ream : square: :penetra-:
S: : : : : inch :- : tion :
-- ------- ----. - -- -- - -- - ----------- -., :- --- : -- - --- --.....-
Number : :Number : :Pound : Mils : Point : Gram : Pound :Percent:Seconds :Percent:Percent

1790A :Engelmann spruce: 394 :None : 37.5 : 3.08 0.21 : 0.4 : 3290 ; 64 : 78 : 93 : 1.5

1790B : Do.......: 394 :Jordaned: 38.2 : 3.32 : .34 : .31 : 3800 : 64 : 109 : 93 : 1.0

1791 :White spruce : 393 :None : 37.0 : 3.36 : .29 : .38 : 3580 : 65 : 153 : 91 : 1.5

Average of 29 commercial newsprint papers 37.0 : 3.20 : .25 : .48 : 2592 : 58 : 48 93 : 1-0

-Standard ream 25 x 40 500. To convert to the newsprint trade ream of 24 x 36 500 multiply by 0.864








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