The process of custom jeans birth represents a long and a hard way. To manufacture only
one pair of jeans one needs to carry out about 100 operations – from fixing different
workpieces to stitching the seams, placing the brand’s logo and special furnishings.
Jeans are produced from initially rough fabrics covered with size and dyed with indigo.
Afterwards jeans undergo wet finishing the main stages of which are desizing, partial dyeing,
washing with neutralization and softening, bleaching, drying.
Desizing is an essential stage of the process, it can function as a final stage or proceed all
other stages of the process. The main aim of it is to soften and a bit dye made to measure jeans.
The dyeing stage uses potassium permanganat and sodium chloride oxide as main reagents. However,
lately hydrogen peroxide is often used for transformation of potassium permanganat into manganese
dioxide, which is safer for workers and more environmental friendly. On this stage generally the
technology of stone-washing is being realized, moreover it is necessary to carefully regulate the
possible number of oxidizers. This is the most important part of the process.
Neutralization generally follows the dyeing stage. During this stage the action of oxidizing
reagents is completed and all rests of chemicals are removed from the surface of tailored
jeans.
During the bleaching stage the finishing procession of jeans is carried out with the help of
different bleachers, softeners and optical bleachers. The contrast between colored and bleached
surfaces is getting higher (light, medium and rodeo).
Of course not necessarily all customized jeans undergo all these finishing stages, the process
can be finished already after the first stage or the second one. It all depends on the effect we
want to get as a result. That is why various shades of denim appear – from dark blue to white, as
well as different fabric structures – from classical brand new to worn to holes.
The color scheme of denim was significantly extended starting from the second half of the 1990s.
Before only indigo and black sulfide dyes were used. Other colors appear, some of them instead
classical ones, others meant specially for overdyeing technology.
Let us take a closer look at these dyes. They can be first of all classified according to the method
of use. In textile industry dyes of eight main classes are generally used. The first five classes of
dyes (direct, sulfide, azoic, reactive and vat) are used mostly for dyeing of cellulose fibers, for
example, cotton and viscose. The last three classes of dyes (acid, basic, disperse) are implied for
dyeing of other natural and synthetic fibers. Denim fabric and designer jeans are generally dyed
with direct, sulfide, and reactive dyes.
Direct dyes can be used without additional chemicals. However, the practice shows that the speed of
dyeing and intensity of color can be upgraded with the addition of inorganic salts.
Sulfide dyes are distinguished by their low cost. However, their main disadvantages are low brightness
and low stability towards wet finishing and light.
Reactive dyes are also sometimes called active dyes and were created in the 1950s. They are very
stable towards wet finishing, are however more expensive compared to direct, sulfide and azoid dyes.
The stability of reactive dyes towards the influence of chloride and other bleachers is sometimes
very low.
The dyeing of jeans can be carried out on the stage of fabric manufacture or after the jeans have
already been made (the so-called garment dyeing). In the first case on the first layer of the fabric
the second layer of the color is put. Generally direct, sulfide and active dyes of black, blue,
gray, brown and green colors are used. This process is usually the last phase in the technology of
jeans manufacture and is generally carried out in the same factory where the fabric is produced.
Steam is used for the color fixing. Unfixed color and additional chemicals are then washed out of
the fabric after the final stage. Generally the fabric is dried on the hot calendar rolls before
putting out of dyeing machine. For radical black colors final wash in vinegar acid for a more stable
color is used.
Personalized jeans made from overdyed fabric undergo abrasive treatment, not only for creating a
worn look. They should be freed from excessive unfixed color to improve consumer and hygienic qualities.
The most common color combinations for overdyeing are dark-blue, blue-gray and blue-green. The so-called
hodi technology is the last trend in tailor jeans procession. It’s main idea is to turn bright blue and
light-blue denim colors into bleached and dirty shades of blue-gray, blue-brown, blue-yellow, blue-pink
and others. The second dyeing process is carried out onto indigo layer and the chemical finishing is
made afterwards.
However, the final look and color of jeans does not depend on the consequence of finishing processes. It
does depend on the proportion and concentration of enzymes and dyes being used.
Historically the first one among chemical processing technologies of designer jeans was stone-washing. It
has been used by Japanese brand Edwin starting from 1975. The next technique was patented by Italian brand
Rifle in 1986 and is based on jeans treatment with pumices stones and acid simultaneously. It is now known
as “acid wash”. A great disadvantage of this method is cold abrasive treatment; besides, it demands much
handicraft and the necessity of much equipment to be used. Constant work with chloride is also considered
to be rather a disadvantage.
That is why today this method is successfully replaced by abrasive and
biochemical and bioabrasive treatments.
Bleaching is a close analogue of any other abrasive treatment. The main aim of this process is to achieve
deep degrees of denim lightening. The look of bleached jeans can be easily distinguished from all other
treatments – their color is light blue coming into white, besides, they have thick locked stitches.
Sandblasting is not widely used compared to other treatments. It is not meant for mass production, however,
is becoming very popular today. Its main aim is to highlight concrete places on custom jeans, by lightening
them. This processing is perfect for artistic people who want to design jeans where they can give way to
their fantasies. Sandblasting probably has good future. People tend to prefer designer jeans more and more
which can be explained by the growing aspiration of each person to achieve freedom and individuality.
By the way, do you know how the first bleached jeans appeared? The history is banal and prosaic like most
great discoveries are. It happened in Greensborough in North Carolina in 1969. The flood ruined the warehouses
of world famous Cone Mills denim factory which is a direct supplier of Levi’s since 1915. Wet fabric, dyed
with unstable color and put into rolls bleached. However, an original way-out was found soon. Wet jeans were
washed in a bleacher solution and irregular patterns were thus created – stains, stripes and rivers. These
novelty jeans were sold-out pretty soon. And this day can be probably considered as the invention of bleached jeans.
Posted: 13.02.2010 by Stella Tornton, fashion journalist, Getwear design jeans fan
