John L. Crist was a founder of Southern Chemical in Charlotte in 1933. The company later became known
as Southern Dyestuff Corporation and then Sodyeco, the largest producer of sulfur dyes in the U.S. Earlier in
his career, Crist had established Beaver Chemical in Damascus, Virginia. He was highly regarded as an
expert on the manufacture of sulfur dyes and their application to textiles.
as Southern Dyestuff Corporation and then Sodyeco, the largest producer of sulfur dyes in the U.S. Earlier in
his career, Crist had established Beaver Chemical in Damascus, Virginia. He was highly regarded as an
expert on the manufacture of sulfur dyes and their application to textiles.
| John L. Crist (1890-1961) Photo: American Dyestuff Reporter, 1957 |
Reproduction of Article by John. L. Crist, "The Place of Sulfur Colors in our War Production", American Dyestuff
Reporter, Vol. 31, No. 6, March 16, 1942, pp. 133-136. Presented at Piedmont Section meeting of the American
Association of Textile Chemists and Colorists, January 24, 1942:
Reporter, Vol. 31, No. 6, March 16, 1942, pp. 133-136. Presented at Piedmont Section meeting of the American
Association of Textile Chemists and Colorists, January 24, 1942:
In the preparation of this paper the purposes of our association as expressed in its by-laws have been kept clearly in mind, namely, "to
promote increase of knowledge of the application of dyes and chemicals in the textile industry; to encourage in any practical way
research work on chemical processes and materials of importance to the textile industry; and to establish for the members channels
by which the interchange of professional knowledge among them may be increased."
It was well toward the end of the first World War and during the post-war period when sulfur colors of domestic manufacture became
available to the textile industry. At this time some of these colors were rather poorly made, and the technique of application was not as
far advanced as at present. Consequently, even though many sulfur colors were dyed and used successfully during this period, and
during the decade following, unfavorable results were at times obtained. Here, as Mark Anthony said, "The evil is longer remembered
than the good." It is now known, even in this period of something like twenty years ago, that many unfavorable results were blamed on
sulfur colors when other factors such as preparation, stripping, aftertreating and finishing were really at fault.
By the time vat colors became available, we were, as present developments painfully prove, unfortunately maintaining an inadequately
small force of more or less professional soldiers, sailors and marines, whose terms of enlistment were for relatively long duration.
Therefore, the quantity of cotton goods required for our armed forces was correspondingly small and could easily be dyed with
available vat colors. Since in many instances these goods were carried in storage for long periods, it was the logical procedure to
specify vat colors for most cotton goods used by our defense forces. The procurement agencies remembered the relatively few
unsatisfactory experiences they had had with sulfur colors and it seemed to them that these could be best avoided by specifying vat
dyes.
Now that we are engaged in a full, all-out war effort with a greatly expanded armed force in all branches, and since a large portion of
the cotton goods which are to be produced for and consumed by these agencies is intended for immediate distribution and use, and
further since the present requirements are on such a tremendously large scale, a definite shortage of certain vat colors, strategic raw
materials, and intermediates from which they are made has developed. It is therefore perfectly logical for our procurement agencies,
and for the textile and dyestuff industries, to make a careful study and a thorough survey to determine if and where sulfur colors can be,
and should be, specified and accepted instead of vat and other dyes. The speaker wishes to testify to the open-mindedness, sincerity,
and desire to learn the truth on the part of our procurement agencies and government departments. They understand much progress
has been made in the past twenty years and that more satisfactory and dependable results are obtainable with modern sulfur dyes
applied by modern methods than were possible in the first World War.
By specifying sulfur colors wherever the requirements are such that this group of dyestuffs can be used to produce satisfactory and
acceptable results, there is effected a tremendous saving in essential and strategic materials required by other agencies in this great
war effort. For instance, most of the faster vat colors are made from the basic intermediate, anthraquinone. This, in turn, requires
Phthalic Anhydride (in great demand for plastics), aluminum and chlorine in its manufacture, as well as large quantities of sulfuric acid
and other industrial chemicals and intermediates of which there is a definite shortage. Then, when the dyestuff is to be applied on the
cotton, sodium hydrosulfite is required, which needs zinc in its manufacture. It obviously becomes evident that whatever can be done to
save vat colors will automatically save Phthalic Anhydride, chlorine, aluminum, sulfuric acid, zinc and many other essential chemicals
and materials, all so vitally needed to produce war supplies used by the fighting forces. Sulfur colors also require some intermediates
made from essential materials but the yield of sulfur colors from their intermediates and chemicals both in pounds of color, and in
yards of cloth that can be dyed to a given shade, is so much greater than is true in the case of vat colors that the savings are
tremendous. We will cite an example—
Meta Toluylene Diamine is of course made from Toluene, also the intermediate used in the manufacture of the explosive, TNT, which
is in great demand. Yet, one pound of Toluene (which costs about 4 cents) made completely into MTD and then into sulfur dyes will
produce sufficient sulfur khaki dyestuff to dye approxiamately 600 lbs. of cotton to the army OD-3 shade. This, converted to four-yard
goods, is the equivalent of 2400 yards or, let us say, approximately one and one-half miles of four-yard goods dyed to the OD-3 shade.
Mind you, this is done from one pound of Toluene, costing 4 cents. This is a typical example of the tremendous leverage in the
manufacture of sulfur colors from their intermediates considered either in pounds of sulfur dyestuff or in yards of cloth dyed therefrom.
In the manufacture of vat colors, much larger quantities of the organic intermediates and various chemicals are used than are required
to produce equivalent quantities of sulfur colors. This is also true of equipment, time, labor, fuel, supplies, etc., because there are
many more and longer process steps in the manufacture of vat colors than there are in the manufacture of sulfur colors. Specifying the
use of sulfur colors instead of vat colors where it is logical to do so, greatly relieves the strain on these strategic materials. This is
especially vital at this time, since the intermediate and chemicals used in the manufacture of vat dyes, and the processes in which they
are made, parallel very closely the production of explosives and materials necessary for chemical warfare, all of which are used by and
needed for our fighting forces. This also applies, to a degree, to sulfur colors, but, as pointed out above, to only a fraction of the extent
as with vats.
Owing to the relative abundance of the intermediates and chemicals used in the manufacture of sulfur colors, and the relative ease
and speed of production, there is not now, and it is not contemplated that there will be, a serious shortage in the colors of this class
used for Army work such as prevails in the vat colors and the hydrosulfite necessary for dyeing them. There is in existence in the
dyestuff industry, production capacity far in excess of the present demands for sulfur dyes. This capacity to produce can be further
expanded much more easily and more quickly than is possible with vats, since the sulfur colors require fewer process steps, less
equipment, and shorter time cycles.
The cost of dyeing the Army OD shades with sulfur colors as compared with the cost of producing the same shade with vat colors
reflects the factors discussed above. As a general rule for comparison, the dyestuff and chemical cost to dye these shades with sulfur
colors is from 1/7to 1/12 the cost of dyeing the same shade with vat colors. In dyeing yarn and rawstock, considerably more production
per machine per day is obtained when dyeing sulfur colors than when dyeing the same shade with vats.
It is felt that vat colors should be used to the limit of their availability on the finer counts of fabrics such as combed-yarn drills and twills
and for fabrics that are to be made into garments which receive the most severe treatment. Outside of this field where maximum
fastness is required and where the use of vats is clearly indicated, there are many fabrics which should be specified to be dyed with
sulfur colors such as bedding materials, sleeping bags, linings, silicas, barracks or dunnage bags, Boy Scout clothing, Civilian
Defense Corps clothing, black-out cloth, less expensive work clothing in the fighting forces, perhaps fatigue suitings, socks, cover-alls,
webbings and other fabrics.
Sulfur colors as produced now by reputable manufacturers show great improvement over those colors available during the first World
War. Likewise, the technique of application of this and other classes of colors, has shown much improvement. As a result of these two
factors, goods can be dyed with sulfur colors now that are much faster to light and washing and which have no hazard toward
tendering, such as was sometimes found twenty years ago. It is known that some instances of goods deteriorating in storage were
blamed on sulfur colors when other factors were responsible. Until recently, little care or thought was given to the removal of all
residual acidity following the aftertreating of sulfur colors as is commonly done with chrome and acetic acid, or copper and acetic acid,
or a combination of copper, chrome and acetic acid. Yet it is a recognized fact that when acetic acid is left in goods which are
subsequently heated to high temperatures, tend-ring is brought about, regardless of whether these goods are dyed or with what class
of colors, or are white goods.
Except in the case of full shades of sulfur black, there is no hazard of tendering of goods dyed with sulfur colors, if proper care and
discretion are used in the selection of the colors and in their application. Even in the case of sulfur black, information and procedure
are now available to the dyers which permit dyeing full shades of sulfur blacks and aftertreating them in a way to effectively prevent
tendering in storage. There is very little sulfur black used by our Defense agencies; consequently this is a subject which falls
somewhat outside the scope of this paper.
Since there were isolated cases of sulfur-color dyed goods deteriorating in storage after the first World War, it was deemed desirable
by the procurement agencies to set up methods of testing and to write specifications by which dyers would know that their goods
would not deteriorate and inspectors could check these results. After much careful work, it has been determined that accelerated
tendering tests can be rather easily conducted to determine the amount of deterioration or tendering which takes place over a given
period of time under ordinary storage conditions. This test is carried out as follows:
Samples to be tested should be checked as to alkalinity. It has been determined that residual acidity in the goods will accelerate
tendering; consequently all goods dyed with sulfur colors that are aftertreated with acetic acid should be given a final rinse in dilute
alkali (Soda Ash is entirely satisfactory) so that the goods will have a pH of not less than 9 after dyeing. Care should also be exercised
in the finish of the goods to assure, after finishing, that the goods will be on the alkaline side, having a pH of 9 or above.
Goods to lie tested are heated in an electric oven for two hours at a temperature of 135° C. (275° F.) and then removed from the oven,
allowed to cool to room temperature, exposed in an atmosphere of steam, as over a dye bath, for ten minutes. They are then replaced
in the oven at the temperature of 135° C. and subjected to this heat for an additional period of two hours, with subsequent steaming.
This treatment is repeated the third time, making a total of six hours heating, with steaming after each heating. The goods are then
allowed to condition in the open atmosphere for 18 hours to regain normal moisture.
Breaking tests are made of both warp and filling (or on yarn if it is being tested) in sufficient number to obtain a dependable average.
Similar breaking tests are conducted on a portion of the goods that was not subjected to the heat treatments. It is also desirable to run
a blank check by heating a sample of the undyed goods, which has been similarly adjusted as to alkalinity along with the dyed sample.
Break tests are conducted on the unheated undyed goods and also on the heated undyed goods and compared with the loss of
strength of the dyed goods.
The percentage of strength remaining is calculated by dividing the remaining strength after heating, by the strength before heating. To
be acceptable, goods should retain as much as 75% of their initial strength after this heating, which is considered to be equal to four
and one-half years storage under normal conditions.
Since it has been found and definitely proven that the presence of organic or mineral acids in dyed and finished cotton goods will
accelerate tendering of the goods when subjected to the accelerated tendering test, and that when these goods are finished to a pH of
9 or above, there is no appreciable tendering, the following method of testing the pH of the goods has been developed.
This procedure is intended to check dyed and finished cotton goods for residual acidity or alkalinity. A stock of distilled water containing
a suitable wetting-out or penetrating agent to assure complete and rapid wetting-out, should be first prepared and adjusted to a pH of
9, with a dilute soda ash solution using a potentiometric or a colorimetric method.
10 grams of the goods to be tested is steeped in 150 cc. of the 9 pH water for one hour at room temperature (70° F). Frequent stirring
of the solution and goods is necessary to give accurate results. It is advisable to run a blank of water at the same time and under the
same conditions as when the goods are steeped. After steeping the goods for one hour, they are removed and the pH of the water is
again determined. The final pH of all tested solutions should be 9 or above. Should the pH of the tested solutions be below 9, this is
an indication that the goods contain some acid which will tend to accelerate tendering and the goods should be rejected. When the pH
of the final solution is 9 or above, this is an indication that the goods are on the alkaline side and are therefore acceptable.
The speaker has in his possession samples of OD shades dyed with sulfur colors in 1924 that are now 17 years old. These samples
have been stored under ordinary room conditions. The goods were aftertreated with copper and acetic acid and finished off in dilute
soda ash. They are apparently as strong today as they were when they were woven. The pH is now approximately 8.0. He also has
twelve-year-old samples of OD shades of goods dyed with sulfur colors that were aftertreated with copper and acetic acid and not
neutralized after dyeing. The pH is now about 6.0. These goods show definite tendering; they have lost about one-half of their original
strength. In fact, we have seen tests of goods that were properly dyed with sulfur colors and properly finished that actually resisted the
accelerated tendering tests better than undyed white or grey goods.
To impart the ultimate in fastness to both light and washing, sulfur colors should be aftertreated with either copper or chrome.
Aftertreatments with perborate or peroxide impair the fastness to both light and washing. Aftertreating OD shades with copper and
acetic acid does not cause the goods to tender on ordinary storing, or when subjected to the accelerated tendering test, if the acid in
the goods has been neutralized and if they have been finished off to a pH of 9 or above. The improvement in the fastness of goods
dyed with sulfur colors, when aftertreated with copper or chrome, is considered to be due to the formation of the relatively inert
chromium and copper color lakes formed in the goods. Since sulfur colors are more active in alkaline conditions than in acid, the
formation of these lakes is more readily accomplished if the dyed goods can be aftertreated in a bath which is neutral or slightly
alkaline. This is now being done with chromium salts with superior fastness and other desirable results. The oxidation of the sulfur
colors by chrome and acetic acid or by any other agents does not improve the fastness of the color. As a matter of fact, the fastness is
actually impaired by oxidation. It is the formation of the relatively inert metallic lakes which contributes so much to the improvement in
fastness.
OD shades dyed with sulfur colors and properly aftertreated possess unusually good fastness to light. These shades properly
selected and properly dyed will withstand approximately 75 % as much exposure to Fade-0-Meter and to light as the same shade dyed
with vat colors.
While there is no question but that the vat colors are more permanent and more durable, as a class, than the sulfur colors, and
certainly vat colors should and will be used and specified for the better fabrics which have the most exposure to light and are most
often subjected to laundering, yet sulfur colors, when properly applied, are durable, are relatively easy to apply, and are often as
durable as the cotton goods on which they are dyed. In that great volume of cotton goods listed in part previously which are used by our
defense forces, the use of expensive vat colors made from vital and strategic materials of which there is a shortage, can hardly be
justified when there are readily available sulfur colors of high quality made from materials which are relatively abundant.
Appreciation should be expressed to the officers and technicians in the Quartermasters Department, and to Mr. Lanier and Dr. Lippert
of the War Production Board for their cooperation and helpfulness in working out the tests described herein, and for their untiring
efforts in the solution of the many problems encountered.
Sulfur dyes are being, and will continue to be, used at a greatly accelerated rate. The manufacture of high grade sulfur colors, the
continued development of better types and better methods of their application on goods for our fighting and defense forces, is
constituting a worthwhile contribution to our all-out war effort. Those of us who are engaged in this work, whether it be in developing or
in manufacturing or in selling the dyes, or in the dyeing and finishing of the goods, or in specifying the dyes and procuring the goods,
can confidently feel that we are doing an important job in the conservation of strategic and essential materials.
This job, well done, will be our contribution toward helping our armed forces, and those of our Allies, beat the life out of the
unscrupulous aggressor nations, with whom we are now engaged in this most gigantic of all wars, to preserve our national freedom
and the American way of life.
promote increase of knowledge of the application of dyes and chemicals in the textile industry; to encourage in any practical way
research work on chemical processes and materials of importance to the textile industry; and to establish for the members channels
by which the interchange of professional knowledge among them may be increased."
It was well toward the end of the first World War and during the post-war period when sulfur colors of domestic manufacture became
available to the textile industry. At this time some of these colors were rather poorly made, and the technique of application was not as
far advanced as at present. Consequently, even though many sulfur colors were dyed and used successfully during this period, and
during the decade following, unfavorable results were at times obtained. Here, as Mark Anthony said, "The evil is longer remembered
than the good." It is now known, even in this period of something like twenty years ago, that many unfavorable results were blamed on
sulfur colors when other factors such as preparation, stripping, aftertreating and finishing were really at fault.
By the time vat colors became available, we were, as present developments painfully prove, unfortunately maintaining an inadequately
small force of more or less professional soldiers, sailors and marines, whose terms of enlistment were for relatively long duration.
Therefore, the quantity of cotton goods required for our armed forces was correspondingly small and could easily be dyed with
available vat colors. Since in many instances these goods were carried in storage for long periods, it was the logical procedure to
specify vat colors for most cotton goods used by our defense forces. The procurement agencies remembered the relatively few
unsatisfactory experiences they had had with sulfur colors and it seemed to them that these could be best avoided by specifying vat
dyes.
Now that we are engaged in a full, all-out war effort with a greatly expanded armed force in all branches, and since a large portion of
the cotton goods which are to be produced for and consumed by these agencies is intended for immediate distribution and use, and
further since the present requirements are on such a tremendously large scale, a definite shortage of certain vat colors, strategic raw
materials, and intermediates from which they are made has developed. It is therefore perfectly logical for our procurement agencies,
and for the textile and dyestuff industries, to make a careful study and a thorough survey to determine if and where sulfur colors can be,
and should be, specified and accepted instead of vat and other dyes. The speaker wishes to testify to the open-mindedness, sincerity,
and desire to learn the truth on the part of our procurement agencies and government departments. They understand much progress
has been made in the past twenty years and that more satisfactory and dependable results are obtainable with modern sulfur dyes
applied by modern methods than were possible in the first World War.
By specifying sulfur colors wherever the requirements are such that this group of dyestuffs can be used to produce satisfactory and
acceptable results, there is effected a tremendous saving in essential and strategic materials required by other agencies in this great
war effort. For instance, most of the faster vat colors are made from the basic intermediate, anthraquinone. This, in turn, requires
Phthalic Anhydride (in great demand for plastics), aluminum and chlorine in its manufacture, as well as large quantities of sulfuric acid
and other industrial chemicals and intermediates of which there is a definite shortage. Then, when the dyestuff is to be applied on the
cotton, sodium hydrosulfite is required, which needs zinc in its manufacture. It obviously becomes evident that whatever can be done to
save vat colors will automatically save Phthalic Anhydride, chlorine, aluminum, sulfuric acid, zinc and many other essential chemicals
and materials, all so vitally needed to produce war supplies used by the fighting forces. Sulfur colors also require some intermediates
made from essential materials but the yield of sulfur colors from their intermediates and chemicals both in pounds of color, and in
yards of cloth that can be dyed to a given shade, is so much greater than is true in the case of vat colors that the savings are
tremendous. We will cite an example—
Meta Toluylene Diamine is of course made from Toluene, also the intermediate used in the manufacture of the explosive, TNT, which
is in great demand. Yet, one pound of Toluene (which costs about 4 cents) made completely into MTD and then into sulfur dyes will
produce sufficient sulfur khaki dyestuff to dye approxiamately 600 lbs. of cotton to the army OD-3 shade. This, converted to four-yard
goods, is the equivalent of 2400 yards or, let us say, approximately one and one-half miles of four-yard goods dyed to the OD-3 shade.
Mind you, this is done from one pound of Toluene, costing 4 cents. This is a typical example of the tremendous leverage in the
manufacture of sulfur colors from their intermediates considered either in pounds of sulfur dyestuff or in yards of cloth dyed therefrom.
In the manufacture of vat colors, much larger quantities of the organic intermediates and various chemicals are used than are required
to produce equivalent quantities of sulfur colors. This is also true of equipment, time, labor, fuel, supplies, etc., because there are
many more and longer process steps in the manufacture of vat colors than there are in the manufacture of sulfur colors. Specifying the
use of sulfur colors instead of vat colors where it is logical to do so, greatly relieves the strain on these strategic materials. This is
especially vital at this time, since the intermediate and chemicals used in the manufacture of vat dyes, and the processes in which they
are made, parallel very closely the production of explosives and materials necessary for chemical warfare, all of which are used by and
needed for our fighting forces. This also applies, to a degree, to sulfur colors, but, as pointed out above, to only a fraction of the extent
as with vats.
Owing to the relative abundance of the intermediates and chemicals used in the manufacture of sulfur colors, and the relative ease
and speed of production, there is not now, and it is not contemplated that there will be, a serious shortage in the colors of this class
used for Army work such as prevails in the vat colors and the hydrosulfite necessary for dyeing them. There is in existence in the
dyestuff industry, production capacity far in excess of the present demands for sulfur dyes. This capacity to produce can be further
expanded much more easily and more quickly than is possible with vats, since the sulfur colors require fewer process steps, less
equipment, and shorter time cycles.
The cost of dyeing the Army OD shades with sulfur colors as compared with the cost of producing the same shade with vat colors
reflects the factors discussed above. As a general rule for comparison, the dyestuff and chemical cost to dye these shades with sulfur
colors is from 1/7to 1/12 the cost of dyeing the same shade with vat colors. In dyeing yarn and rawstock, considerably more production
per machine per day is obtained when dyeing sulfur colors than when dyeing the same shade with vats.
It is felt that vat colors should be used to the limit of their availability on the finer counts of fabrics such as combed-yarn drills and twills
and for fabrics that are to be made into garments which receive the most severe treatment. Outside of this field where maximum
fastness is required and where the use of vats is clearly indicated, there are many fabrics which should be specified to be dyed with
sulfur colors such as bedding materials, sleeping bags, linings, silicas, barracks or dunnage bags, Boy Scout clothing, Civilian
Defense Corps clothing, black-out cloth, less expensive work clothing in the fighting forces, perhaps fatigue suitings, socks, cover-alls,
webbings and other fabrics.
Sulfur colors as produced now by reputable manufacturers show great improvement over those colors available during the first World
War. Likewise, the technique of application of this and other classes of colors, has shown much improvement. As a result of these two
factors, goods can be dyed with sulfur colors now that are much faster to light and washing and which have no hazard toward
tendering, such as was sometimes found twenty years ago. It is known that some instances of goods deteriorating in storage were
blamed on sulfur colors when other factors were responsible. Until recently, little care or thought was given to the removal of all
residual acidity following the aftertreating of sulfur colors as is commonly done with chrome and acetic acid, or copper and acetic acid,
or a combination of copper, chrome and acetic acid. Yet it is a recognized fact that when acetic acid is left in goods which are
subsequently heated to high temperatures, tend-ring is brought about, regardless of whether these goods are dyed or with what class
of colors, or are white goods.
Except in the case of full shades of sulfur black, there is no hazard of tendering of goods dyed with sulfur colors, if proper care and
discretion are used in the selection of the colors and in their application. Even in the case of sulfur black, information and procedure
are now available to the dyers which permit dyeing full shades of sulfur blacks and aftertreating them in a way to effectively prevent
tendering in storage. There is very little sulfur black used by our Defense agencies; consequently this is a subject which falls
somewhat outside the scope of this paper.
Since there were isolated cases of sulfur-color dyed goods deteriorating in storage after the first World War, it was deemed desirable
by the procurement agencies to set up methods of testing and to write specifications by which dyers would know that their goods
would not deteriorate and inspectors could check these results. After much careful work, it has been determined that accelerated
tendering tests can be rather easily conducted to determine the amount of deterioration or tendering which takes place over a given
period of time under ordinary storage conditions. This test is carried out as follows:
Samples to be tested should be checked as to alkalinity. It has been determined that residual acidity in the goods will accelerate
tendering; consequently all goods dyed with sulfur colors that are aftertreated with acetic acid should be given a final rinse in dilute
alkali (Soda Ash is entirely satisfactory) so that the goods will have a pH of not less than 9 after dyeing. Care should also be exercised
in the finish of the goods to assure, after finishing, that the goods will be on the alkaline side, having a pH of 9 or above.
Goods to lie tested are heated in an electric oven for two hours at a temperature of 135° C. (275° F.) and then removed from the oven,
allowed to cool to room temperature, exposed in an atmosphere of steam, as over a dye bath, for ten minutes. They are then replaced
in the oven at the temperature of 135° C. and subjected to this heat for an additional period of two hours, with subsequent steaming.
This treatment is repeated the third time, making a total of six hours heating, with steaming after each heating. The goods are then
allowed to condition in the open atmosphere for 18 hours to regain normal moisture.
Breaking tests are made of both warp and filling (or on yarn if it is being tested) in sufficient number to obtain a dependable average.
Similar breaking tests are conducted on a portion of the goods that was not subjected to the heat treatments. It is also desirable to run
a blank check by heating a sample of the undyed goods, which has been similarly adjusted as to alkalinity along with the dyed sample.
Break tests are conducted on the unheated undyed goods and also on the heated undyed goods and compared with the loss of
strength of the dyed goods.
The percentage of strength remaining is calculated by dividing the remaining strength after heating, by the strength before heating. To
be acceptable, goods should retain as much as 75% of their initial strength after this heating, which is considered to be equal to four
and one-half years storage under normal conditions.
Since it has been found and definitely proven that the presence of organic or mineral acids in dyed and finished cotton goods will
accelerate tendering of the goods when subjected to the accelerated tendering test, and that when these goods are finished to a pH of
9 or above, there is no appreciable tendering, the following method of testing the pH of the goods has been developed.
This procedure is intended to check dyed and finished cotton goods for residual acidity or alkalinity. A stock of distilled water containing
a suitable wetting-out or penetrating agent to assure complete and rapid wetting-out, should be first prepared and adjusted to a pH of
9, with a dilute soda ash solution using a potentiometric or a colorimetric method.
10 grams of the goods to be tested is steeped in 150 cc. of the 9 pH water for one hour at room temperature (70° F). Frequent stirring
of the solution and goods is necessary to give accurate results. It is advisable to run a blank of water at the same time and under the
same conditions as when the goods are steeped. After steeping the goods for one hour, they are removed and the pH of the water is
again determined. The final pH of all tested solutions should be 9 or above. Should the pH of the tested solutions be below 9, this is
an indication that the goods contain some acid which will tend to accelerate tendering and the goods should be rejected. When the pH
of the final solution is 9 or above, this is an indication that the goods are on the alkaline side and are therefore acceptable.
The speaker has in his possession samples of OD shades dyed with sulfur colors in 1924 that are now 17 years old. These samples
have been stored under ordinary room conditions. The goods were aftertreated with copper and acetic acid and finished off in dilute
soda ash. They are apparently as strong today as they were when they were woven. The pH is now approximately 8.0. He also has
twelve-year-old samples of OD shades of goods dyed with sulfur colors that were aftertreated with copper and acetic acid and not
neutralized after dyeing. The pH is now about 6.0. These goods show definite tendering; they have lost about one-half of their original
strength. In fact, we have seen tests of goods that were properly dyed with sulfur colors and properly finished that actually resisted the
accelerated tendering tests better than undyed white or grey goods.
To impart the ultimate in fastness to both light and washing, sulfur colors should be aftertreated with either copper or chrome.
Aftertreatments with perborate or peroxide impair the fastness to both light and washing. Aftertreating OD shades with copper and
acetic acid does not cause the goods to tender on ordinary storing, or when subjected to the accelerated tendering test, if the acid in
the goods has been neutralized and if they have been finished off to a pH of 9 or above. The improvement in the fastness of goods
dyed with sulfur colors, when aftertreated with copper or chrome, is considered to be due to the formation of the relatively inert
chromium and copper color lakes formed in the goods. Since sulfur colors are more active in alkaline conditions than in acid, the
formation of these lakes is more readily accomplished if the dyed goods can be aftertreated in a bath which is neutral or slightly
alkaline. This is now being done with chromium salts with superior fastness and other desirable results. The oxidation of the sulfur
colors by chrome and acetic acid or by any other agents does not improve the fastness of the color. As a matter of fact, the fastness is
actually impaired by oxidation. It is the formation of the relatively inert metallic lakes which contributes so much to the improvement in
fastness.
OD shades dyed with sulfur colors and properly aftertreated possess unusually good fastness to light. These shades properly
selected and properly dyed will withstand approximately 75 % as much exposure to Fade-0-Meter and to light as the same shade dyed
with vat colors.
While there is no question but that the vat colors are more permanent and more durable, as a class, than the sulfur colors, and
certainly vat colors should and will be used and specified for the better fabrics which have the most exposure to light and are most
often subjected to laundering, yet sulfur colors, when properly applied, are durable, are relatively easy to apply, and are often as
durable as the cotton goods on which they are dyed. In that great volume of cotton goods listed in part previously which are used by our
defense forces, the use of expensive vat colors made from vital and strategic materials of which there is a shortage, can hardly be
justified when there are readily available sulfur colors of high quality made from materials which are relatively abundant.
Appreciation should be expressed to the officers and technicians in the Quartermasters Department, and to Mr. Lanier and Dr. Lippert
of the War Production Board for their cooperation and helpfulness in working out the tests described herein, and for their untiring
efforts in the solution of the many problems encountered.
Sulfur dyes are being, and will continue to be, used at a greatly accelerated rate. The manufacture of high grade sulfur colors, the
continued development of better types and better methods of their application on goods for our fighting and defense forces, is
constituting a worthwhile contribution to our all-out war effort. Those of us who are engaged in this work, whether it be in developing or
in manufacturing or in selling the dyes, or in the dyeing and finishing of the goods, or in specifying the dyes and procuring the goods,
can confidently feel that we are doing an important job in the conservation of strategic and essential materials.
This job, well done, will be our contribution toward helping our armed forces, and those of our Allies, beat the life out of the
unscrupulous aggressor nations, with whom we are now engaged in this most gigantic of all wars, to preserve our national freedom
and the American way of life.
 |  |  |  |  |  |
Sulfur Colors in World War II
ColorantsHistory.Org