Hemp Hurds as Paper-Making Material Part 3

-----------+-----+------+-------------------+----------+ | | | Weight of 500 | | Laboratory | Run | | sheets. |Thickness,| No. | No. | Ash. +---------+---------+ 1/10000. | | | | | | | | | |25 by 38.|25 by 40.| | | | | | | | -----------+-----+------+---------+---------+----------+ | |_Per | | | | | | ct._ |_Pounds._|_Pounds._| | 31570 | 144 | 13.9 | 48 | 50-1/2 | 33 | 31571 | 143 | 14.5 | 49 | 51-1/2 | 35 | 31572 | 142 | 9.5 | 49-1/2 | 52 | 33 | 31573 | 141 | 10.9 | 48 | 50-1/2 | 38 | 31574 | 140 | 11.4 | 42 | 44 | 30 |[Transcriber's 31575 | 139 | 13.4 | 55 | 58 | 40 | note: Table III 31576 | 138 | 10.4 | 56 | 59 | 40 | continues below]

-----------+--------------------------+----------+------------------------- | Strength (Mullen). | | Folding endurance.

Laboratory | | Strength | No. +--------+--------+--------+ factor +-------------+----------- | | | |(25 by 40,| | |Average.|Maximum.|Minimum.| 500). |Longitudinal.|Transverse.

| | | | | | -----------+--------+--------+--------+----------+-------------+----------- | | | | | | | | | | | | 31570 | 15.0 | 17.0 | 11.0 | 0.30 | 5 | 3 31571 | 14.0 | 14.0 | 13.0 | .28 | 4 | 4 31572 | 19.0 | 20.0 | 19.0 | .37 | 8 | 6 31573 | 16.5 | 18.0 | 11.0 | .33 | 10 | 8 31574 | 14.5 | 16.0 | 13.0 | .33 | 7 | 6 31575 | 19.5 | 20.0 | 17.0 | .34 | 8 | 5 31576 | 20.0 | 20.0 | 19.0 | .34 | 23 | 15 -----------+--------+--------+--------+----------+-------------+-----------

There is no system of numerically recording the general appearance and "look through" of a paper, but it can be stated that only papers Nos.

143 and 144 are satisfactory in these respects, the other samples being more or less thickly specked with s.h.i.+ves. The general character and tests of these papers correspond very closely with No. 1 machine-finish printing paper, according to the specifications of the United States Government Printing Office, which call for a sheet not exceeding 0.0035 inch in thickness, strength not less than 12 points, free from unbleached or ground wood pulp, and ash not over 10 per cent. The strength factor of such papers is about 0.28. The ash should not be over 10 per cent for this grade of paper, but in spite of the larger amount used the physical tests are sufficiently high. It is to be noted that the physical tests of samples Nos. 138 to 142, inclusive, are higher than in Nos. 143 and 144, in which 23 per cent of soda poplar was used, which shows clearly that hemp-hurd stock imparts strength and folding endurance to a greater extent than does soda-poplar stock. From these preliminary tests it would be concluded, therefore, that hemp-hurd stock acts similarly to soda-poplar stock, but will produce a somewhat harsher and stronger sheet and one of higher folding endurance. Undoubtedly, there is more dirt in the samples than would be tolerated by the trade, but this was to be expected, since in this preliminary work the raw material was sieved by hand screens instead of by automatic machines which would sieve more thoroughly.

=CONCLUSIONS.=

There appears to be little doubt that under the present system of forest use and consumption the present supply can not withstand the demands placed upon it. By the time improved methods of forestry have established an equilibrium between production and consumption, the price of pulp wood may be such that a knowledge of other available raw materials may be imperative.

Semicommercial paper-making tests were conducted, therefore, on hemp hurds, in cooperation with a paper manufacturer. After several trials, under conditions of treatment and manufacture which are regarded as favorable in comparison with those used with pulp wood, paper was produced which received very favorable comment both from investigators and from the trade and which according to official tests would be cla.s.sed as a No. 1 machine-finish printing paper.