INDUSTRIAL A N D ENGINEERlNG CHEMISTRY
916
Potassium xanthate is a desirable soil fumigant but too expensive for acreage treatment except on crops yielding high profits, the cost for an acre being from $30 to $50. Eradication cannot be expected but only varying degrees of control for 1or possibly 2 years. The most satisfactory use of soil fumigation is in nurseries and beds and trucking or orchard soils.
VOl. 20, s o . 9
Xanthate has given practical control of the garden nematode in the 2 years’ experimentation, but the scope of the work is too limited to warrant recommending definite measures. Xanthate has not given control of the sugar beet nematode, Heterodera schachtii Schmidt.
Influence of Laundering on Cotton Fabrics’ Especially with Washing Agents Containing Sodium Perborate P. E. Raaschou and V. Ahrend Larsen LABORATORY FOR GENERAL TECHNICAL CHEMISTRY, POLYTECHNICAL COLLEGE, COPENHAGEN, DENMARK
On boiling cotton fabric, under definite conditions, with solutions containing 1 per cent of soda, 0.5 per cent of sodium hydroxide, l per cent of water glass, or l per cent of soap in hard water, reduction in tensile breaking strength increases with a n increasing number of boils, and t h e amount of this weakening is in t h e order in which these solutions are named. A mixture of 0.33 per cent of soap, 0.33 per cent of soda, and a small quantity of water glass (0.04 per cent in the lye) produces a very slight weakening. The addition of a small quantity of perborate (0.01 per cent of the lye) to these solutions increases the weakening, which in certain cases, however, is slight in comparison with the weakening influence of the pure laundering agent. The addition of increasing quantities of perborate (0.01 t o 0.15 per cent of the washing lye) to the standard lye causes a pronounced decrease in the strength. Special soiling of t h e fabric causes an additional weakening, when t h e boiling is done with the standard lye plus 0.05 per cent of perborate. On boiling with distilled water
(containing a trace of copper) a n especially pronounced weakening is found when the standard lye plus 0.05 per cent of perborate is used. A comparison of the breaking-strength tests with tests on the dissociation of the perborate during t h e boils shows t h a t boiling with a lye retarding the perborate dissociation results in a low degree of perborate-weakening, and vice versa. Thermostatic tests of the perborate dissociation show the factors accelerating and retarding the dissociation. Determinations of the quantities of ash and incrusted substances have been made, t h e latter according to a special method. In a single washing series a comparison has been made between the loss of weight and the loss of strength during the washing. An attempt has been made t o separate the total weakening during washing into the following individual factors-incrustation weakening, perborate weakening, and other causes of weakening.
H E Great War gave impulse to investigations concerning the injurious effects exerted on cloth by washing preparations, especially in countries suffering from scarcity of raw materials for textiles and washing agents, and during recent years interesting results have been obtained. A review of the more important washing investigations carried on in Germany was published in 1925 by Heermann.2 The principal object of the present investigation was to ascertain the degree to which cotton materials are weakened by being washed with so-called self-acting washing preparations-i. e., preparations containing perborates and other bleaching agents. In order.to procure a basis of comparison, washing tests were performed with the usual washing preparations, both separate and mixed with each other, paftly with and partly without sodium perborate. I n addition, to ascertain the purely mechanical wear occurring in home laundering, tests were conducted by the usual method of washing clothes by hand. The weakening of textile fabrics by washing preparations, in particular those containing sodium perborate, depends on the manner and the degree to which the fabrics are soiled. The fabrics were therefore soiled with various substances before they were washed-with mixed fruit juice for slight soiling, and with tea and claret for more or less intense soiling.
Preliminary investigations were also made of the processes of decomposition of the perborate in the various washing preparations and mixtures thereof employed, in order to find the relations between the quantity of perborate decomposed, or the speed of its decomposition and the extent to which the materials were weakened by the perborate. Further, quite independent, tests were made to ascertain the effect of various ions on the rate of decomposition of the perborate. Finally a study was made for some of the specimens in each series of washes, the contents of ash and incrusted substances formed by adsorption, on the fabric, of the laundering agents and the calcium salts of the washing water.
T
1 Received November 6, 1926. Revised manuscript received April 24, 1928. “Die Wasch- und Bleichmittel und Ihre Einwirkung auf Gewebe Nnd Game,” Verlag des deutschen Waschereiverbandes. e. V., Berlinkchterfelde. f
Materials Used
TEXTILES-TWO qualities of cotton cloth were used: Medium heavy unbleached cotton cloth: Weight, 133 grams per square yard (159 grams per square meter) Number of threads per cm., 33 in warp direction, 23 in weft direction Yarn, 24 warp and 24 weft ( b ) Light cotton cloth: Weight, 36 grams per square yard (13 grams per square meter) Number of threads per cm., 48 in warp direction, 46 in weft direction Yarn, 120 warp and 110 weft
(a)
WASHING WATER-Hard water (Copenhagen water supply) was used, the composition being:
INDUSTRIAL A,VD ENGINEERING CHEMISTRY
September, 1928 Tra.ce 117 65.5
HSOa
cot
HCI
33
H&Od
CaO MgO
137 23
Residues from evaporation dried at 130’ C. Consumption of oxygen for oxidation of dissolved organic substances “3. “02, HIPO~
447 0.1 0
Distilled water, which a special examination showed to contain about 0.06 mg. of copper per liter, was also used. Finally, for pure dissociation tests redistilled water, containing no appreciable quantities of catalysts for the perborate dissociation, was used. L~UXDERING AGmTs-The chemicals used in the preparation of the washing lye in the various series were of the following composition: Sodium hydroxide Water glass Soda Soap Perborate
V
88.17 NaOH 2 5 . 0 8 SiOz, 7.57% NazO 8 5 . 8 % NazCOs 8 5 . 2 % fattyacid, 7.5670 Na, h.O6% water 1 0 . 3 % active oxygen
Washing Tests
The tests tTere performed in enameled-iron tubs under uniform conditions. The soiled cotton fabric was introduced into a lye a t a temperature of 50” C., which was then heated For 30 minutes to 100’ C., and boiled for a further 30 minutes. The material was stirred frequently. Between the washing processes the test fabrics were rinsed, and the water was removed by hand pressure (no wringing) before drying. The manual washing was performed by allowing the fabrics to soak in cold water, scrubbing them for 5 minutes with soap and soda on a scrubbing board, boiling for 30 minutes in a 1 per cent soap solution, and finally rinsing and drying. Tensile-Strength Tests of Washed Fabrics
PROCEDURE-These tests were effected by means of a Schopper tensile-strength testing machine having a maximum capacity of 100 kg. The apparatus was tlriven by water power. The specimens were strips of 100 threads each cut from the washed fabrics in both warp and filling directions. The humidity of the air before and after the tensile tests was maintained a t 65 per cent. Check measurements with Assmann’s ventilation psychrometer showed the deviations from this humidity to be less than 1 3 per cent. The result of each test was registered automatically by the Schopper machine, which was fitted with a special device causing a style to describe a curve on a cylinder in such a manner that the abscissa was proportional to the tensile stress and the ordinate proportional to the elongation. Figure 1 shows ten such individual curves each corresponding to one tensile breaking test. The ten strips were cut in the ~ a m edirectian from the same piece of cloth. The curves run from right to left. The initial points are 1.5cm. apart in a vertical direction, the style of the recording device being raised 1.5 cm. after earh test. The left-hand end points indicate the breaking points. Since these curves represent the same piece of cloth cut in the same direction, the abscissas measured from the right to the end of the curves also give an idea of the degree of uniformity of the results. A computation of the relative mean error, f, of the mean value, by aid of the formula f =
4 s
where d indicates the difference between the. individual result and the mean value, and n, the number of tests, shows that .f is equal to about 2 per cent for the group of ten individual tests. RESULTS--The upper part of Figure 2 shows the results of washing tests with medium heavy cotton cloth, speciniens for tensile-strength tests being taken after 10, 20, 30, 40, and
917
50 washings. The figures given for 10, 20, 30, and 40 boils are the average of 40 individual breaks, 20 in the warp direction and 20 in the filling direction. The figures after 50 boils are the mean of 20 individual tests (10 in the warp direction and 10 in the filling direction). Strips of 100 threads each were tested in each case. The strength is given in per cent of the original strength (desized cloth). The lower part of Figure 2 shows the results of washing tests with thin cotton fabric. All curves were determined from tests after 20 and 40 boils, the figures being the mean of 20 individual tests, loin the warp direction and 10 in the filling direction, on strips of 100 threads each. On using the usual washing agents-viz., a 1 per cent solution of soda, a 0.5 per cent solution of sodium hydroxide, a l per cent solution of water glass, and a 1 per cent solution of soap-boiled in ordinary manner with slightly soiled (mixed fruit juice) c o t t o n f a b r i c s , a weakening was found which increased in the order that these agents a r e n a m e d . ( F i g u r e 2, series 1 to 4) The weakening, for medium heavy fabric after 50 boils, and Figure 1-Graphical Record on for light fabric’after Schopper Ap aratus of One Individ4 0 boils. i s shorvn i n ual T e n s i l e - d s t Series A-Tensile strength; B-Elongation Table I. Table I-Reduction
of Strength Caused by Usual Washing Agents MEDIUM HEAVY LIGHTCOTTON FABRIC FABRIC P e r cent P e r cent Soda 3 26 Sodium hydroxtde 9 25 Water glass 13 31 Soap 24 42
It is surprising that the soap solution caused the greatest weakening, as this is contrary to what other investigators have found. However, comparison of these curves with the corresponding perborate curves, as well as with those for the hand-washed heavy fabric, which was boiled in a soap solution, after each washing, shows quite uniform weakening, and seems to confirm the present writers’ results. It is possible that both the soap and the water were of different quality than those with which other investigators have worked, and the weakening may perhaps be due to a chemical or physical action of the large quantities of incrusted calcium soaps. (Table IV) Mixed laundering agents-viz., a mixture of 0.33 per cent of soap, 0.33 per cent of soda, and 0.04 per cent of water glass dissolved in hard water-cause only a very slight weakening of medium heavy fabric after 50 boils, and of light fabric after 40 boils. A solution of 0.33 per cent of soda plus 0.33 per cent of soap in hard water (series 6) causes a considerably greater weakening than the same lye with the further addition of 0.04 per cent of water glass. In the presence of this small auantitv of water elass the formation of calcium-soaD in&ustat:on in the f a k c is presumably less than in the series with hard water without water glass. (Table IV)
918
ILYDUSTRIAL AiVD ENGINEERING CHEMISTRY
Vol. 20, No. 9
tenslle strer&.th ir. 0
0
0
0
0
3 0
i c
I
M
ISDCSI'RIAL A,ITD E.VGI;VEERI,VG CHEJfISTRY
September, 1928
Figure 2, series 1 to 4, shows that the addition to the lye of a small quantity of perborate (0.01 per cent) generally increases the weakening, which in certain cases, however, may be slight in comparison with the weakening influence of the pure laundering agents. This applies to slight soiling (mixed fruit juice). Table 11-Effect of Addition of Perborate to Standard Lye on Strength of Fabric DECREASE I N STRENGTH Medium h e i v y ~ Light AMOUNT OF PERBORATE fabric fabric SOlLINO ADDED (50 boils) (40 ttoils) Per cent Per cent Per cent ~~
H A R D WATER
DISTILLED WATER
0.05
(TRACE
OF
presence of fruit juice greatly accelerates the rate of decomposition. The slower dissociation in series 5e (Figure a), special soiling, than in series 5c, fruit juice, must be due to the fact that in the second case it is taking place mainly in the lye, and in the first case largely on the fibers. Tests have been made to find the general relations between the additional weakening caused by perborate in combination with the various washing preparations and the rate of decomposition of the perborate in such preparations. The value, per single boil, for the additional weakening caused by perborate is calculated by dividing the perborate weakening by the respective number of boils and these values are given in Table 111. Table 111-Perborate Weakening per Single Boil PER C E X T O F SERIES MEAKSTRENGTH NaOH-perborate 0.26 0.20 Soda-perborate Soap-perborate 0.15 0.05 Water glass-perborate
cu) 63
38
A comparison of these tensile-test results with those of decomposition tests (Table 111)has shown that boiling with a lye retarding the perborate decomposition gives a slight perborate weakening (additional weakening caused by the content of perborate) and vice versa. The weakening is rapidly increased by the addition of increasing quantities of perborate to a standard lye, consisting of a solution czontaining 0.33 per cent of soap, 0.33 per cent of soda, and 0.04 per cent of water glass, as will be seen from Figure 2, series 5 , and Table 11. 5 The considerable weakening found by boiling with laundering lye prepared with distilled water is evidently due in part to the 4 circumstance that pure distilled water by itself causes greater weakening than hard water under otherwise similar conditions, but 3 the main cause of the weakening is probably the presence of copper in the distilled water, since this tends to produce a catalytic dis- 2 sociation of the perborate on the fibers. HANDWASHIXGTEsTs-These tests have shown that the additional weakening caused 1 by the mechanical treatment of cotton fabrics is immaterial in the case of ordinary manual washing. The weakening of textile fabrics by ordinary manual washing seems therefore to be due essentially to the chemical action \ 9 A of the washing preparations. Rate of Decomposition of Sodium Perborate
BOILS-Samples were taken from the perborate-containing lye a t suitable intervals during the boiling, and the concentration of oxygen was determined by titration with thiosulfate, after any soap present had been removed by addition of hydrochloric acid and separation of the fatty acids by means of carbon tetrachloride. Figure 3 shows the rate of decomposition of sodium perborate during these washing tests. The curves were determined from the mean of two or more independent boils. The decomposition proceeds most slowly in water glass-perborate lye, faster in solutions of soap-perborate and soda-perborate, and fastest in solutions of sodium hydroxideperborate. The order is the same for stained .and original (not stained) materials, and the
The order for the perborate weakening seems to be the same as for the perborate decomposition rate or the quantity of dissociated oxygen in the same series. DETERBIINATIOXS IN THERMOSTAT-A.series of determinations was made of the rate of dissociation of the perborate, mainly a t 50" with a maximum deviation of +=0.1" C., in minu t ea, clean c o t t o n material s o i l e d cotton material
c o n o o e i t l o n of l y e :
1.
2.
3. 4.
standard l y e : I/? % aoau i / j % ;odd 0.04
*
6
4 r(
2 a
5
4 0
4
%
wa-
ter glase,
6
DETERMINATIONS DURIXG LAUNDERIXG 7
919
1 % w a t e r glaes + 0.01 $ pecborate ( i n i t i a l percent) 1 % soap do. 1 %soda do. $ c a u s t i c aoda do.
a
+ +
+
standard l y e + 0 . 1 5 % ( i n i t i a l p e r c e n t ) perborate ( c l e a n c o t ton m a t e r i d ) la. do. ( s o i l o d material 2 . standard l y e +O.o5 $ pexb. (cleau matarial) do. (soiled m a t & r i a l ] do. (spec. soiled) do. ( d i s t i l l e d wat,er, do. c l e w material) ( d i s t i l l e d water, s o i l e d mat.: 5. standard l y e + O . o l 7 perborate [ c l e a n mat.erial] 5a. do. (soiled material:
I,
U 0
3 1
Figure 3-Dissociation
Rate of Sodium Perborate during Washing Process
INDUSTRIAL A N D ENGINEERING CHEMISTRY
920
order to ascertain the influence of the ordinary laundering agents and the water-hardening agents, and the action of various substances retarding or accelerating the dissociation. .4 pure sodium perborate from Kahlbaum was used. The experiments were conducted in three-necked glass vessels in a thermostat with constant agitation. Unless otherwise stated, redistilled water was used and gave coincident curves when conditions were alike. The ordinary distilled water a t hand gave widely varying results, probably owing to small contents of copper (averaging about 0.06 mg. per liter). The oxygen concentration was generally determined according to the permanganate m e t h ~ d . ~Only when soap was present a titration with thiosulfate was made after the liberated fatty acids had been removed by means of carbon tetrachloride. Figures 4 and 5 show effect of various salts, etc., on the rate of decomposition of the perborate. The effect of the individual salts will not be discussed in detail here, but the tests as a whole indicate that the rate of decomposition of the perborate depends partly on the following factors: (1) The hydrogen-ion concentration, since the decomposition
* Holde, “Kohlenwasserstoffbleu. Fette,” p. 697, Berlin, 1924. time i n minutes 100 150
50
50
100
increases with the pH value in all cases up to a certain limit, after which a further increase of the hydroxyl-ion concentration will cause the rate of decomposition t o be again reduced. A similar occurrence has been noted in the case of hydrogen peroxide.4 Menze15has discussed the combination of hydrogen peroxide t o boric acid and borate ions and the affinity properties of perboric acid. ( 2 ) The action of the other ions, which in some cases (Cu, Mn, Fe, series 2 and 9) may be regarded as a positive catalytic action, while the action of the stabilizing ions, such as calcium and magnesium may consist in the formation of more stable per-salts or peroxides. Water glass per se does not appear t o be a stabilizing compound (series 4). In combination with magnesium ions it has a lesser modifying effect on these ions than soda and sodium hydroxide (Figures 3 and 4, series 6). Series 2 , Figure 4,shows that calcium and magnesium ions have a stabilizing effect in the presence of copper ions, while water glass (sodium silicate), on the contrary, increases the speed of decomposition when Cu++ions are present. (3) The rate of decomposition depends on the presence of organic acceptors for the oxygen, such as the organic constituents of raspberry juice, fatty acids, etc.
The results show clearly that in carrying out the washing tests to ascertain the effect of the perborate on the fibers, it is necessary to pay attention to the composition of the water used, and it is probable that several of the discrepancies between the results found by various investigators may be due to differences in the composition of the water, the washing preparations, and the substances used for soiling the fabric.
50
150
15c
100
Ash and Incrusted Substances in Washed Fabrics
50%.
4
4
1 . hard d o n e s t . v a t e r 2 . r e d t s t i l l e d do. 3 . destllled do.
-
1. n/lOO QCl2 I. d o + n/lOOOOO CuS04 ?, 4 1 0 0 ~ a ~ 1 2 do in/lOOOOO CuSOq ~JIOOOOO M ~ S O ~ 7 . n / l O O O O O CuS04 ‘a do 4 2 0 HapSiOj
I:
+
I
I
60% ./%o:c.
I
I
800c.
1-2
4
-6O’C.
-
80%.
50
2.
3.
I
I
100
150
Figure 4
4 800C.
1. n / 1 0 0 &c12 do+ 4 2 0 Nasi03 do+n/20 Na C O 3 4 . do 4 2 0 N ~ H
1. r e d i s t i l l e d water 2. 4 2 0 Na2Si03 3. 4 2 0 U a O H 4 . 4 2 0 Na2C03
Vol. 20, No. 9
+ I
I
L
50 100 1: tlme in m i n u t e s
For ascertaining the effect of the washing preparations on the fibers themselves the tensile-strength test alone is not sufficient, as it is possible that the substances which are adsorbed on them and originate from the water and the washing agents may, in case of continuous washing, have some influence on the strength. Furthermore, these substances will greatly affect the properties of the washed fabric, in respect to appearance, touch, weight per unit of surface, elasticity, etc. The quantities of ash and incrusted substances for the various washing tests have therefore been determined in both heavy and light cotton fabrics. (Table IV) The incrustations were removed by treatment with 2 per cent formic acid, 1 per cent hydrofluoric acid, and in certain cases ether. Blank tests showed that these chemicals did not appreciably reduce the weight of the fibers themselves. From Table I V it appears that the quantity of incrusted substances when washing with Copenhagen drinking water depends on the washing preparation used, as such preparations form insoluble compounds with the hardness-producing substances in the water, and these insoluble compounds are adsorbed on the fibers. The incrustation is at 4 Birckenbach, “Die Untersuchungen des Wasserstoffsuperoxyds,” p. 40, Stuttgart, 1909. 5 Z. physik. Chcm.. 106, 402 (1923).
September, 1928
I X D USTRIAL AiVD ENGINEERING CHEMIXTR Y
921
within this series certain regularities could be ascertained. Figure 6 18 shows that the strength is reduced more rapidly than the weight, which 16 means that a t any rate an appreciable 14 portion of the loss of strength is due to the fact that the organic sub12 stance becomes converted, and 10 thereby weakened, by the perborate. 8 If the action of the perborate is 6 0 uniform over the entire surface of the fibers, then the removal, by solu4: tion, of a superficial layer will cause 0 a weakening proportional to the de2 U crease in weight, provided that all 0 % the converted cellulose goes into the 0 Tolution and the remainder retains s its original strength. This reasoning, on the other hand, evidently does not apply when the action is localized. It should be noted that the weakening due to incrustation (see 18 next section) does not play any im16 portant part in this series. How14 ever, since oxidation usually means an increase of weight a t first, there 12 is no reduction in weight until some of the compounds formed have been 10 dissolved in the washing lye or rea moved mechanically during or between the washing operations. 6
15
14 12
1 : 8
6 4
Relative Influence of Various Weakening Factors on Resultant Weakening '; . c
4 8
422
2 %
L 6
$0
0 :
a,
n
An attempt was made to determine separately the weakening of 4 the fibers due to incrustations and 4u to the perborate and, from the difrerenee between these two weakenings and the total weakening, the t i n e i n 8:r:utes wiakening which must be due to other causes. IluCRUSTATIoxS-Ten consecutive strips from a portion of the washed material were selected as tensile-test specimens. Every second strip was exposed to de-incrustation as described above. After equilibrium of humidity had been attained, the tensile strength WRS determined for each strip. Owing to lack of material, the strength was determined only 3
4. 0 0 0
Figure 5
a minimum where sodium hydroxide is used and a maximum where water glass or soap is used. I n case of soap the acids of high molecular weight form relatively heavy calcium and magnesium salts which are decomposed by incineration. Reduction of Weight of Fibrous Substances by Washing
In order to obtain the greatest possible turning of the scales, the pieces of fabric that had been exposed to a large number of boils (40 or 50) were used. From each of these three specimens of exactly 200 X 200 threads were selected. These specimens were submitted to the de-incrustation process, and then dried, cooled, and weighed separately in closed weighing glasses. In similar manner the quantity of dry substance in de-sized and de-incrusted original cloth was determined. The results must be considered unreliable on account of the lack of uniformity of the textiles, the relatively small specimens it was practicable to handle and, possibly, the imperfection of the method of de-incrustation. Therefore, only a single series will be discussed in detail-viz., heavy fabric, special soiling (Figure 2, series 5e), where the loss of weight was particularly pronounced. The loss of weight for increasing number of boils was determined and it was found that
Table IV-Ash
a n d Incrusted Substances in Washed Fabrics MEDIUM HEAVY COTTON LIGHTCOTTON (50 BOILS) (40 BOILS) COMPOSITION OF LYE Ash Incrusted Ash Incrusted
SERIAL 1 la 2 20 3 3a 4 4a 5
5a 5b 5C
5d 5e 6
6a 7
NaOH 0 . 0 1 % perborate Same 1% water glass 0 . 0 1 % perborate Same 1% soda Same 0 . 0 1 % perborate 1% soap 0 . 0 1 % perborate Same Standard lye 0 . 0 1 7 perborate Same 0 , 0 5 8 perborate Same Same 0.15% perborate 0 . 0 5 7 0 perborate, Same special soiled material Same 4- 0 . 0 5 % perborate, distilled water =/a% soda, '/a% soap, distilled water Same, hard water Hand washing I/a%
+ + + +
+ + + +
%
%
%
%
3.3 3.3 43.0 43.5 11.8 11.6 4.7 5.4 12.0 12.2
4.5 4.0 36.8 31.0 14.8 16.3 3.9 3.0 16.6
9.3 8.6
5.3 5.0 53.7 52.4 15.3 15.7 50.5 46.4 24.1 22.6 19.6 17.7 17.7
6.1 6.5 44.1 44.9 23.3 23.5 29.9 27.4 31.3 30.4 27.0 20.4 17.5
0.8
0.7
0.7
1.4
0.08
0.1
0.1
0.9
9.2 2.8
26.6 25.7
lo,,
16.7 15.6
11.5 11.5
INDUSTRIAL A N D ENGINEERING CHEMISTRY
922
for one way of the cloth, the warp. Blank tests in which the de-incrustation method was applied to fabric practically free of incrustations had shown that the treatment had a negligible influence on tensile strength. When the cloth tested contained incrustations it became apparent, in nearly all cases, that these incrustations (originating from the hardness producers and the laundering agents) had a weakening effect on the cloth, since their removal caused an increase in tensile 0
10
20
30
40
50 of Washings
E
Lose of Weight i n c a s e o f UeI n c r u e t e d Fabric
10
20 Washing S e r i e s No.50 Composition o f Lye:
30
Soap
0.33 $
Soda
0.33 $
Water Glans 0.04
Perborate 0.05
Figure 6-Loss
% 5
\
LOSS
of
6trenGth I n c a g e o f Inc r u n t e d Fabric
of Weight and Strength Due to Perborate Washing
s Irength. This incrustation weakening, however, was generally only a small percentage of the original strength. I n the cases where water glass alone and water glass plus perborate had been used (Figure 2, series 2), considerable incrustation weakenings were found, however, due presumably to calcium silicate, etc. Thus, for heavy fabric, 40 boils, 1 per cent of water glass in the lye, an incrustation weakening of 20 per cent was found and for heavy fabric, 40 boils, 1 per cent water glass plus 0.01 per cent of perborate in the lye, it was 22 per cent. In
Vol. 20, No. 9
both cases the incrustation weakening represents most of the total weakening caused by laundering. Similarly for light fabrics considerable incrustation weakenings were found in the water-glass series. For 40 boils, one way, an incrustation weakening of 15 per cent was found in the water-glass series, but only 13 per cent in the water glass-perborate series. This may explain the fact that in certain cases the perborate-curve may lie above the nonperborate curve (Figure 2, series 2, light cotton fabric). By the use of washing preparations with high contents of water glass it must be considered probable that an extra weakening may occur due to substances incrusted on the fibers. This weakening may also be evident when the fabrics become exposed to mechanical forces during actual use. PERBORATE WEAKENING-The perborate weakening is computed as the difference between the strength, one way of the cloth, with incrustations after 40 boils with perborate, and the corresponding strength without perborate. The results are shown in Table IV, and the figures are computed from the test material for which the final results are illustrated in Figure 2. The incrustation weakening is here assumed to be the same for the corresponding perborate and non-perborate curves, which seems to be largely justified from the tests described. The investigations indicate clearly that the perborate weakening increases with increasing perborate concentration in series 5, a to d , and remarkably uniform values for heavy and light cotton fabrics are obtained. Table V-Reduction Series
of Strength Warp Direction after 40 Boils, Due t o Action of Perborate 5d 5c 5a 5b 5c
7 0 % Perborate added to standard lye Reduction of strength: Heavy fabric Light fabric
0
0.01
0 0
3’ 1
%
%
%
0.06
0 15
0.05
8
7
19 19
22 22
OTHERCAUSESOF WEAKEP~’ING-T~~ remaining differential weakening must be due mainly to the chemical action exerted on the fibers by the washing preparations (except the perborate) , but possibly also partly to mechanical causes such as modification of the friction between fibers, felting, mercerizatisn, swelling, etc. This weakening is indicated by the varying slope of the strength curves (Figure 2, all non-perborate curves). Only in series 2 does the incrustation weakening play any essential part.
Newsprint Paper from New Zealand Hardwoods h’ewsprint paper, equal in quality to American standards, has been made from New Zealand hardwoods by the U. S. Forest Products Laboratory, Madison, Wis., after a year of experimentation for the New Zealand Forest Service. The final test was the production of several tons of newsprint and rotogravure papers a t two Wisconsin mills and the running of the newsprint paper over the presses of a daily newspaper. The arrival at thinning age of 100,000 acres of fast-growing planted forests in New Zealand and the consequent desire to put the plantations on a sound production basis through profitable utilization of thinnings prompted the attempts to use two native species and four introduced species in the manufacture of newsprint and other papers. The Forest Products Laboratory undertook the investigation in the belief that results might be obtained which would be applicable t o American species. This belief has been justified. The development of this process opens up possibilities in the use of American hardwoods (hitherto unused for this purpose) for newsprint production in this country. The pulping trials of New Zealand woods began when Alex R. Entrican, engineer in forest products representing the New Zealand Forest Service, arrived a t the Forest Products Laboratory with two carloads of logs. For the purposes of the pulping trials two New Zealand woods and the insignis pine were considered most important. The main objectives of the experiments were to produce a pulp or pulps suitable for newsprint from the available species, particularly rimu (the dominant New Zealand softwood), tawa (a New Zealand hardwood unsuited to the production of lumber), and insignis (Morterey) pine;
a satisfactory kraft (dark-colored wrapping) pulp from pines and larch; and bleached chemical pulps. These objectives were realized in a gratifying way. A satisfactory newsprint sheet was produced from mixtures of tawa groundwood and tawa sulfite (chemical) pulp with insignis pine sulfite. Satisfactory kraft pulps were produced from the New Zealand pines and larch, and bleached pulps suitable for book paper and similar products were produced from tawa by the soda and sulfite processes and from insignis pine by the sulfite process. The development of a satisfactory newsprint process for tawa and insignis pine-there are also indications that bleached rimu and European larch might be added or substituted-holds interesting possibilities for New Zealand in a n economic way. New Zealand at present buys newsprint from Canada and England. Conservatively weighted cost figures for the manufacture of newsprint from tawa and insignis pine indicate that a newsprint mill established in New Zealand could compete with Canadian pulp laid down in hTew Zealand ports and possibly could hold its own in any price-cutting competition that might arise. It is estimated that New Zealand could absorb the output of a mill producing 100 tons of pulp daily, with a tendency to increase the demand. The production of newsprint from hardwoods is of great significance in the United States. With spruce, the “Old Reliable” of newsprint, and hemlock nearing depletion in this country, with finished newsprint, pulpwood, and pulp being imported in quantities, and with the prospect of increasing rather than decreasing prices, diversification of any sort should be welcome.
