an article to explain the ways to improve dyeing and finishing productivity

1. Wet Processing Productivity Management
Dr. Muhammad Mushtaq Mangat
mushtaq.mangat@gmail.com
mushtaq.managt@moderno.com.pk
(Your comments will be highly appreciated)
1 Introduction
Bleaching, dyeing, printing and finishing of textile materials are very important for end-to-end
textile and clothing production process. There are many ways to explain the whole process.
Commonly the term Wet Processing (WP) expresses the whole manufacturing process. There are
many other phrases, which are commonly used for example textile chemistry, dyeing or
finishing. We shall use the term “wet processing” to explain the whole process in this article.
This term removes all possible ambiguities. We can define the WP in the following words:
"Wet Processing is a process in which fiber; yarn, fabric or garments are treated with
dyes and chemicals to achieve certain colors and to impart required hand-feel and some
special properties."
2 Wet Processing Technology
WP is a complete process, in which, we take textile materials in order to color and finish them
according to the requirements. Textile materials may be raw materials for example fiber, yarn,
and fabric or a finished product for example a garment. However, there are different machines
for different types of materials. Normally dyes and chemicals, which are used in different textile
manufacturing processes, are same to some extent. There are four major processes in wet
processing:
1. Bleaching (Preparation)
2. Dyeing
3. Printing
4. Finishing
In bleaching department, we remove all impurities both natural and added. For this purpose,
textile materials are processed with different chemicals like detergents, desizers, bleaching

2. agents etc. In dyeing department, textile materials are put into contact with different dyes by
using different machines, which depends upon the type of textile material. Some auxiliaries
are also used to make dyeing process smoother and faster. The third department in wet
processing is printing. In printing department, textile materials (mainly fabric or garments)
are printed with the help of different machines and in some cases, manual printing is done on
them. In finishing department, we apply different mechanical and chemical finishes to textile
materials. For this purpose, different machines are used along with some chemical
application. Its purpose is to explain the ways and techniques to improve productivity of this
department. Explanation of wet processing is beyond the scope of this study.
3 Dyeing Cost and its Bifurcation
Following are main factors, which contribute to the cost of wet processing of textile materials:
1. Chemicals
2. Utilities (steam, electricity)
3. Wear and tear (maintenance)
4. Depreciation
5. Labor cost
6. Financial charges/interest charges/financial service charges
7. Any other fixed expenses/costs
It is important to note that the share of different factors in total cost varies from product to
product and also depends upon the type of process. For example, in case of white knitted fabric,
cost of dyes will be negligible, whereas in case of dark shades, cost of dyes will be higher.
Moreover, in case of garment dyeing, labor costs are normally more than yarn-dyeing cost when
manufacturing is done with the help of computerized machines.
4 Measuring Productivity
There are many methods of measuring productivity but the most common method of measuring
productivity is using the ratio of output to input. Moreover, many additional terms are used to
describe productivity. Here, we shall briefly discuss some of them for better understanding of
productivity.

3. 4.1 Partial productivity
Ratio of one factor to output for example production/labor cost
4.2 Total factor productivity
Ratio of more than one factor and output for example production/ (labor +electricity)
4.3 Total Productivity
Ratio of whole output to all inputs for example production/ (labor + raw material costs +
utilities)
There are many other terms related to productivity, which are not in the scope of this work for
example, green productivity, social productivity and sustainable productivity etc. Our focus of
discussion is partial/total factor and the total productivity.
4.4 Factors Affecting WP Productivity
There are a number of factors, which can influence the WP productivity. We can divide these
factors into two main categories; input (dyes, chemicals, fuel for boiler, electricity & labor) and
processes (the way WP is done). Keeping all these factors in mind, we have selected the
following factors, which have significant impact on the WP:
1- Selection of Dyes
2- Selection of chemicals
3- Procurement of dyes and chemicals
4- Weighing and dozing systems of dyes and chemicals (small and bulk quantities)
5- Machine modification
6- Process standardization
7- Production planning
8- Issuing of dyes and chemicals
9- Application of Information Technology

4. In the following pages, we shall discuss the impact of above mentioned factors and ways to
improve their partial productivity.
5 Dyes Selection and Procurement
It is obvious that that dyes' cost has minimum contribution in the cost of producing lighter shades
and maximum contribution in the cost of producing darker shades. It is assumed that by
increasing dyes' productivity (partial productivity of WP), we can improve productivity of the
WP. There are a few dyes' manufacturers in Pakistan. Mainly Pakistani market depends on
imported dyes. Korea, Taiwan, China and India have a major share in dyes manufacturing
industry. Very few manufacturers are importing dyes from Japan and Europe because of their
high costs.
Dyes selection mainly depends upon:
1- Customer’s Quality Standards
2- Machinery Under Use
3- Technical Staff's Competence
4- Credit Availability from Suppliers
5- Price
6- Availability
7- Certification of hazard free production (without using dangerous chemicals)
We can reduce the share of dyes' cost in total cost structure and hence, we can improve WP
productivity. There are many ways to improve it. Some of those are:
1- By directly importing
2- By selecting most suitable dyes
3- By having close business relations with dyes manufacturers
4- By using different dyes for light and dark colors
5- By using accurate balances

5. 5.1 Direct import of dyes
By importing dyes directly from manufacturer reduces cost of dyeing. There is 10-15% cost
difference between costs offered by international and local suppliers. Moreover, every company
maintains stocks, which saves it from any shortage during the production process. International
suppliers also provide assurance that banned chemicals are not used in dyes. After the
enforcement of REACH by Europe, it is now impossible to export goods containing banned
chemicals. If any laboratory finds such chemicals, it is illegal to sell those goods in the Western
World.
Firms can save a lot on cost by borrowing from banks and using banking credit for the importing
dyes. In addition to all above-mentioned monetary benefits, firms can achieve the following
additional benefits:
1- More reliability of dyes
2- No shortages
3- Effective dyeing process
4- More manageable production process
5- Better reproducibility
5.2 Different Dyes for Lighter/Medium/Darker Shades
Dyes' cost has only 4% share in the total dyeing cost of producing light shades. It is commonly
observed that during dyeing, lighter shades are more difficult to dye as compared to medium and
darker shades. Most common problem is uneven distribution of dyes (uneven shade) and
reproducibility. High quality dyes manufacturers (mainly European manufacturers) claim that
their dyes have better evenness and high reproducibility. At the same time, these dyes are
expensive. In some cases, their cost may be twice as compared to cheaper Chinese dyes. After
having a long discussion with dyers, we have concluded that for lighter shades, a manufacturer
should prefer using expensive dyes. This will increase the inventory level of dyes. But on the
other hand, it is also important to note that for lighter shades, larger quantity dyes are not
required. A small quantity is quite sufficient for the whole year. But with a little increase in price

6. and inventory level, we can reduce the reprocessing percentage (re-dyeing or addition)
significantly, which helps in cutting manufacturing costs.
5.3 Dye Selection
There are many factors, which can influence the decision of dyes' selection. However, following
factors should be considered:
1- Fastness (Washing, Rubbing and Light)
2- Shade Depth
3- Leveling
4- Compatibility
5- Dyeing Time and Temperature
6- Reproducibility
A manufacturer should select dyes keeping in mind the above-mentioned factors. It has been
observed that to save a little in the cost of dyes, we might face a big problem. For example, if we
have to stitch white and dark fabric panels in a garment, we need high washing fastness as
compared to a solid garment. Any minor dye bleeding in case of panel stitching of different
colors can lead us to a loss because it can affect our white fabric due to poor washing fastness of
dark fabric. In such cases, a big loss might take place.
Other than above-mentioned factors, we should focus on the following factors:
1- Accurate dye weighting measuring balances (preferably electronic balances)
2- Proper use of dye kitchen
It is assumed that by adopting the above-mentioned recommendations, a manufacturer can save
up to 25% of the cost of dyes.
6 Selection and Procurement of Chemicals (Generic and Auxiliaries)
Chemicals contribute approximately between one fifth and one third share in total cost of dyeing
and averaging 25% share in total dyeing cost. It can be reduced significantly. There are many
ways of improvement. Some of them are listed below:

7. 1- Using concentrated chemicals
2- Importing chemicals is normally are cheaper than buying same chemicals from the local
market
3- Continued testing of new chemicals
4- Identification of the optimum level of chemical consumption
5- Storage in proper place
6- Proper arrangements for taking chemicals from drums
In the following lines, we'll briefly explain all above-mentioned factors.
6.1 Use of Concentrated Chemicals
Two types of chemicals are used in WP including generic chemicals and auxiliaries. Hydrogen
Peroxide, Caustic Soda, acids etc. are called generic chemicals, while softening agents,
detergents, levelers etc. are called auxiliaries. In both cases, chemicals are available in diluted
and concentrated forms, which may vary from 10% to 100%. It has been observed that
manufacturers use both concentrated and diluted chemicals. It depends upon the business
approach and its utilizing mechanism.
Most of the chemicals are imported in Pakistan because Pakistan does not domestically produce
most of them. Only a few chemicals are made in Pakistan. There are firms, which import
concentrated chemicals and formulate them according to the customer’s requirements and sell
them in the local market. Some firms are importing concentrated chemicals and diluting them for
the utilization of the local industry.
We have observed that there is a significance difference between the costs of diluted and
concentrated chemicals. There are many drawbacks of diluted chemicals. Some of them are
listed here:
1- High cost of packaging and transportation
2- Difficult to handle
3- Need more space for storage
4- Uncontrolled dilution

8. Keeping all the mentioned facts in view, it is recommended that manufacturers should use
concentrated chemicals instead of diluted chemicals. In the following lines, we'll explain the
impact of diluted chemicals on the cost of production with an example.
Cationic softener is commonly used to soften the fabric. This is available in:
1- Flakes and concentrated paste form
2- Paste of flakes 10-15% (solid contents)
Using flakes can easily make paste. No big plant is required and no technical process is involved
in the dilution process. Dilution of flakes is quite simple and the flakes manufacturers always
guide the manufacturers how to make paste by using flakes. In addition to that, negligible cost is
added in the dilution process. But there is a great difference in the cost of production.
There are many other chemicals, which are commonly available in the market both in
concentrated and diluted forms. A list of such chemicals is given below, which can be imported
in the concentrated form rather than in the diluted form from the local market:
1- Anti Foam
2- Dispersing agents
3- Leveling Agents
4- Anti-creasing agents
5- Special finishes
6- Sequestering Agents
There are many other chemicals, which can be purchased in the concentrated form.
6.2 Testing of New Chemicals
Chemicals and auxiliaries market is a rapidly changing market. Every company is trying to
develop newer, cheaper and more effective chemicals. We can quote many examples for
example alkali buffers replaced soda ash, three-in-one chemicals replaced caustic, detergent, and
stabilizer etc.

9. Manufacturers normally have less information about new chemicals, because most of production
line workers, supervisors, and even owners of textile industries are not well qualified. In some
cases, new chemicals can create problems and they might not work in combination with other
chemicals but the process of introducing and discovering new chemicals cannot be stopped
because new chemicals can be helpful for decreasing production cost. For example, Silicone
based fabric softeners are used to provide a good hand feel and elasticity to the textile material.
In case of fabric, particularly the fabric for ladies should have a better hand feel along with
elasticity. For knitted garments, only better hand feel is needed because knitted fabrics are
naturally very elastic. There is a significant difference in the price of above mentioned two
silicone based fabric softeners. It has been observed during an industrial survey that many firms
are still using expensive chemicals even when a cheaper alternative chemical can provide the
required results. This is only possible by the continuous testing of alternative chemicals.
6.3 Identification of Optimum Level of Consumption
In most of the cases, manufacturers of auxiliaries recommend a specific combination for better
results. In case of generic chemicals, it depends upon the experience and expertise of the people
who use them. There is a big range of possible recommendations. For example, it is commonly
written that softener A can be used 2-3% OWM (on weight of material). Apparently it seems that
there is a difference of only 1% but in fact, there is a difference of 33% between the lowest and
the highest value. The optimum level for a particular process depends on many factors for
example type of textile material (TM), required quality standards and machines under use etc.
Identification of optimum level of chemical usage for manufacturing is as important as the right
medicine dose for humans. There are many ways to identify the optimum level. The most
common method is lab research and its application in bulk. This phenomenon can be understood
more easily from the example of bleaching time with hydrogen peroxide. It is mentioned in the
literature provided by hydrogen peroxide manufacturers that for best results, TM should be
treated at boiling temperature for one hour. It has been observed that for full bleach,
manufacturers treat the TM at boiling temperature for one hour. There are many factors, which
can influence this bleaching process for example quality of TM, water hardness, and machine
type etc. Running machines for one hour is not recommended in all cases. The treating time is

10. different for different TM, different water hardness and for different qualities. But unfortunately,
in most of the cases, TM is treated for one hour. Researches should be conducted to find out the
exact time for different cases.
There are many other examples of time variations because spending less or more than the
required time can incur losses. It is assumed that we can save some losses by using the
recommended quantity, time, temperature and machinery. Following are some possibilities of
losses:
1- Less use of wetting agents in bleaching increases the dyes' consumption
2- Extra use of caustic soda increases fabric roughness
3- Extra use of antifoam negatively affects the output quality
4- Extra use of softener affects its draping properties
5- Less use of softener can decrease stitching production because needle punching becomes
difficult
6- Extra use of softener can block the needle eye
7- Less use of softener will not give required results in raising/brushing
Based on all the facts given above, we can say that there is a need to know the optimum level of
consumption of chemicals.
7 Storage of Chemicals
Every product used in WP has certain shelf life. Dyes and chemical manufacturers print storage
instructions on the packing. Almost all the packs have a written instruction to store in a cool and
dry place because their strength loses gradually during storage. It may be due to heat or moisture.
In some cases, oxidation of the chemicals is also possible. For example, sodium sulphide
becomes oxidized when it is exposed to air because of presence of oxygen in the air. It loses its
strength after oxidation. Some chemicals lose their strength due to high temperature. For
example, hydrogen peroxide can lose its strength up to 5% if stored at 50C° for more than three
months.

11. In some cases, bacteria can grow due to long time storage or pastes can get fungus if antifungal
poison is not added, which is quite harmful for people and the environment. Certain chemicals
are highly flammable especially petroleum based chemicals. They should be stored properly.
Many tragic incidents have happened so far. Some chemicals can catch fire if they come in
contact with water and ultimately become unusable for example Sodium Hydrosulphite.
8 Dyes and Chemical Feeding to Machines
There are two steps in dozing; first to get dyes and chemicals from the drums and then feeding
them to machines. Chemicals are supplied in plastic drums while dyes are supplied in cartons.
Very common practice is to use plastic mug to take chemicals out of drums. In some cases,
drums are laid down on the slab and chemical is taken out by pouring. In both cases there is a
loss of chemicals. Following problems are more likely to occur:
1- It is dangerous
2- It creates problems
3- It causes loss
4- There is a chance of unwanted mixing of two or more chemicals or unwanted chemical
reactions
To avoid all these problems, following methods are suggested:
1- Pumping of chemicals
2- Storage in big tanks
3- Direct supply to machine tanks
4- Auto Dozing system
Certainly, mistakes and problems can be avoided by adopting the recommended measures.
9 Machine Operators
Mostly, dyeing houses are not fully automated while mills have semiautomatic systems. In most
of the cases, machines are operated manually. In fact, we do not have any training arrangements
of WP operators because most of them only get on-the-job training. They learn by mistakes and

12. mostly operators have less formal education. Less qualified and barely trained machinists and
operators cause following issues:
1- Reprocessing rate increases
2- Higher consumption of dyes and chemicals
3- Delays in delivery
4- Increased dyeing time
Following methods can help overcoming these problems:
1- Operators' training
2- Automation
In WP, every function is related to time for example hot wash is carried out at 70C° for 15
minutes but it is manually quite difficult. It is observed that more than 50% variations are due to
operators' performance and manual machine settings. It has been observed that if there is a less
or compromised control on production process, more variation will be found in processing
particularly in processing during evening and night shifts.
It is advised to initiate fully automated processes or cost effective semiautomatic systems in WP.
Some fully automated mills are not performing well because the production culture of Pakistan
resists the automation while semiautomatic system is more effective in Pakistan because it can be
operated by less educated and trained people. This system is more feasible and can save the
dyeing time and consumption of dyes and chemicals.
10 Machine Modification and Maintenance
It is a universal truth that proper machine maintenance plays an important role in better
productivity. Normally, maintenance is not given its due attention and a lot of time is wasted due
to maintenance problems. We collected data of a WP department and came to the conclusion that
5- 10% production can be increased by proper maintenance of machines. Furthermore, it is quite
interesting to note that in most modern machines, big difference is observed in the heating,
filling and drain areas. Dyeing time in modern machines is almost the same as the older models

13. of machines. We can modify our existing machines and can have better productivity. In the
following lines, we will explain it with the help of some examples.
10.1 Examples of Modification
1- Using extra tank (may be common for many machines) filled with heated water to reduce
the heating time because it is possible to supply hot water to the machine
2- Motorized suction of water
3- High pressure supply of water
4- Supply of high temp/pressure/dry steam
During an experiment in a mill, hot water tanks with more capacity than the machine cap were
placed near the machine at a certain height and those machines have no built-in pre-heating
tanks. Later, a water tank is attached with three dyeing machines and arrangements were made
to heat it with steam. There was an auto temperature control fixed on this machine. We managed
to store hot water with temperature more than 85°C all the time. Workers were trained to take hot
water from this tank instead of taking cold water from the water storage tank. This arrangement
saved the machine time which was required to increase water temperature from 25 °C to 80 °C.
By doing so, we saved two hours per batch and five hours in a day and got 20% more production
from the same number of machines.
Cost of this system is not more than Rs. 0.2 Million per machine but savings are significant.
Same is the case with filling and draining of the machine. Water is filled more than 14 times in
soft flow dyeing machine during reactive dyeing process. Normally it takes five to seven minutes
for draining and filling. Drain with gravity leaves a lot of effluents in the machine, which creates
problems in next processes but motorized suction and supply can reduce 50% time. It means that
it can save one hour, which is 10% of the total time. We can increase 10% production from the
same machines.
In addition to all above areas, high temp steam (high pressure) can also reduce the time. Most
commonly, boilers have 150 pounds per square inch pressure (PSI). It has been observed that
boilers are operated at 100 PSI and ultimately supply of steam at low-pressure increases the
heating time. By increasing pressure, we can save 5-10% of the total dyeing time. It is important

14. to note that dyeing time of knitted fabric on modern machines is 5-6 hours while it is 8-10 hours
with older machines. Main time saving is in heating, cooling, feeding of chemicals, filling and
draining but not in dyeing time, which is the same in both cases (one hour in case of reactive
dyeing). We can reduce 25% dyeing time just by doing some modifications in the machines.
11 Summary of Improvement Areas
1- 25-30 % in the price of local and imported dyes
2- Suitable dyes as per requirements of the customers
3- Different dyes for light and medium/dark shades
4- Importing concentrated chemicals
5- Testing of new chemicals
6- Proper handling of dyes/chemicals in stores
7- Training of operators
8- Using small trolleys and lifters for the movement of fabric
9- Machine automation
10- Machine modification
11- Supplying high temperature/pressure steam
During a survey of the industry, we have observed that there are many areas, where improvement
is possible. It is true that every factor does not have a significant impact. But it is also true that
small factors can jointly create a greater impact and synergies.
Few observations of the areas, where improvements are possible, are mentioned below:
1- No lifter in WP hall: Big trolleys (over 1000 kg on each trolley) can be used with many
workers pushing them. Lifter can reduce labor requirements and can enhance the production
speed.
2- No pumps in dyes/chemicals stores: Use of mugs etc creates danger and causes the loss of
dyes and chemicals.
3- High cost of chemicals and dyes: More than 85% of the total purchase of dyes and chemicals
from local market increases the cost of production.

15. 4- Continuing the use of old chemicals: Manufacturers are generally reluctant to test and switch
to new chemicals.
5- No modification of machines: Minor changes in machines can significantly increase their
productivity.
6- Boiler at 100 PSI: Increases the dyeing time.
There are many other areas, which need our attention for example finishing and material
movement etc.
In this article, we have explained only dyeing section of the WP. There is a great need that we
should discuss every part of the mill to improve its productivity. We are quite sure that there is a
chance of 20-25% improvement in WP productivity by adopting the above-mentioned methods.