WATER IN FUR DRESSING AND DYEING
The assertion has often been made, although its absurdity is now quite
generally realized, that the success of the European fur dressers and
dyers, particularly in Leipzig, is due to the peculiar nature of the
water used, which is supposed to be especially suited for their needs.
The achievements in this country in the fur dressing and dyeing industry
during the past few years are ample and sufficient answers to the claim of
foreign superiority in this field no matter what reason may be given, and
particularly when the quality of the water used is advanced as a leading
argument. For the water employed by the establishments in and about New
York, as well as in other sections of the country is surely not the same
as the water of Leipzig, yet the work done here is in every respect the
equal of, if not better than the foreign products.
It is interesting to note that similar rumors were current here in the
early period of the development of the American coal-tar industry since
1914. Our efforts to establish an independent dyestuff industry were
doomed to failure, according to those who circulated the stories, because
we did not have the water, which they claimed was responsible for the
German success. The present status of the American dye business, in its
capacity satisfactorily to supply most of the needs of this country and
of others as well, speaks for itself.
However, as is often the case with such erroneous assertions, there
is just enough of an element of truth in the statement regarding the
peculiar qualities of certain kinds of water, to make the matter worthy
of consideration. Water is certainly a factor of great importance in fur
dressing and dyeing, and it is not every sort of water that is suitable
for use. This fact was recognized by the early masters of the art, for
they invariably used rain-water as the medium for their tanning and dyeing
materials, and their choice must be regarded as an exceedingly wise one.
While the necessity for giving consideration to the quality of the water
for fur dressing purposes is great, it is in fur dyeing that the effects
of using the wrong water are largely evident, and so extra care must be
exercised in the selection of water for this purpose.
The essential requirements for a water suitable for the needs of the
fur dressing and dyeing industry, are: first, a sufficient, constant
and uniform supply; and second, the absence of certain deleterious
ingredients. Chemically pure water is simply the product of the
combination of two parts by volume of hydrogen with one part by volume
of oxygen. Such water can only be made in the laboratory, and is of no
importance in industry. For practical purposes, distilled water may be
regarded as the standard of pure water. Here, too, the cost and trouble
involved in the production of distilled water on a large scale is
warranted only in a certain few industrial operations. A natural source
of water which in its character most nearly approaches distilled water
is rain. In fact, rain-water is a distilled water, for the sun’s heat
vaporizes the water from the surface of the earth forming clouds, which
on cooling, are condensed and come down as rain. Rain-water is usually
regarded as the purest form of natural water. Exclusive of the first
rain after a dry period, rain-water is quite free of impurities, except
possibly for a small percentage of dissolved atmospheric gases, which
are practically harmless, and which can usually be readily eliminated
by heating the water. Moreover, rain-water is quite uniform in its
composition throughout the year in the same locality, and it possesses
all the desirable qualities of a water suited for fur dressing and dyeing
purposes. Formerly when the quantity of water used in the industry
was comparatively small, the supply from rain was sufficient to meet
all the requirements. But now, when tremendous quantities of water are
used constantly, rain-water is no longer a feasible source, and other
supplies must be utilized, although in a sense, all water may be traced
to rain-water as its origin.
When rain-water falls on the earth it either sinks into the ground until
it reaches an impervious layer, where it collects as a subterranean
pool, forming a well, or continues to flow underground until it finally
emerges at the surface as a spring; or on the other hand the rain-water
may sink but a short distance below the surface, draining off as ponds,
lakes or rivers. In the first case the water is called ground water, in
the latter it is known as surface water. Ground water usually contains
metallic salts in solution, and relatively little suspended matter. If
the water has percolated through igneous rocks, like granite, it may be
quite free even of dissolved salts, and such water is considered “soft.”
If, however, the rocky formations over which, or through which, the water
has passed contain limestone or sandstone, or the like, salts of calcium
and magnesium will be dissolved by the water. The presence of the lime
and magnesia salts, as well as salts of aluminum and iron, in the water,
causes it to be what is termed “hard.” Surface water is more likely to
contain suspended matter, with very little of dissolved substances.
Suspended matter, like mud, contains much objectionable matter such
as putrefactive organisms and iron, but most of these materials can be
removed by filtration or sedimentation, and seldom cause any difficulties.
Hardness in water is generally the chief source of trouble when the water
is at fault. Hardness may be of two kinds, either permanent, or temporary,
or sometimes both are found together. Water which is permanently hard
usually contains the lime and magnesia combined as sulphates. Temporary
hardness, on the other hand, is due to the presence of lime and magnesia
in the form of bicarbonates, the carbon dioxide contained in the water
having dissolved the practically insoluble carbonates:
CaCO₃ + CO₂ + H₂O = Ca(HCO₃)₂
calcium carbon water calcium
carbonate dioxide bicarbonate
Temporary hardness can be eliminated by heating the water, the carbon
dioxide being expelled and the carbonates of lime and magnesia being
precipitated and then filtered off. Both permanently and temporarily hard
waters can be softened by the addition of the proper chemical, such as
an alkaline carbonate like sodium carbonate. This precipitates insoluble
carbonates of the lime, magnesia, iron and aluminum, leaving a harmless
salt of sodium in solution in the water. The sludge is allowed to settle
in tanks before the water is used.
In fur dressing and dyeing, water is employed for soaking and washing the
skins, dissolving chemicals, extracts and dye materials, and also for
steam boilers. A small amount of hardness in the water is not harmful,
and up to 10 parts of solid matter per 100,000, may be disregarded.
Permanent hardness is particularly objectionable in water for boiler
purposes, as it forms scale. The effect of the impurities of the water
depends on the nature of the chemicals and dyes used. Where acids are
used in solution compounds of magnesium, lime and aluminum will generally
not interfere. Hard water must not be used for soap solutions, as sticky
insoluble precipitates are formed with the soap by the metals, this
compound adhering to the hair, and being difficult to remove, will cause
considerable trouble in subsequent dyeing. An appreciable loss of soap
also results, as one part of lime, calculated as carbonate will render
useless twelve parts of soap. In tanning or mordanting, where salts of
tin, aluminum or iron are employed, hard water should not be used, as lime
and magnesia will form precipitates with them. Bichromates will be reduced
to neutral salts, and cream of tartar will also be neutralized. With dyes
also, hard water has a deleterious effect. Basic dyes are precipitated by
this kind of water, rendering part of the dye useless, and also causing
uneven and streaky dyeings. Sometimes the shades of the dyeings are
modified or unfavorably affected. Considerable quantities of lime and
magnesia in the water will cause duller shades with logwood and fustic
dyeings. The presence of iron, even in very slight quantities generally
alters the shade, darkening and dulling the color.
These facts were apparently all recognized and understood by the fur
dressers and dyers of an earlier period, for instead of utilizing the
water of lakes and streams near at hand, which afforded a more constant
supply, but which contained harmful impurities, they collected the
rain-water, which was always soft. Whether they realized the nature
and character of the substances that make water hard is uncertain,
but they were always careful to avoid such water. At the present time
establishments located in and about large cities like New York, where
the majority of American fur dressing and dyeing plants are situated,
have no trouble about the water. The cities supply water which is soft,
suitable alike for drinking and industrial purposes. Other plants, not
so fortunately situated, often have to employ chemical means to treat the
water so as to make it suitable for use.