Friday, February 12, 2010

Color Matching in Textiles

Colour is one of the most fundamental aspects of textile design which contributes greatly to the overall visual effect of a finished fabric. Colour matching is a vital process in ensuring continuity of colour from the master standard to all subsequent production batches.
A variety of conditions affect how a color looks
1.Light- source difference
2.Observer Difference
3.Size Difference
4.Background Difference
5.Directional difference
How to Ensure Effective Color in Today's Manufacturing Processes?
The three components of colour matching
There are three components involved in colour viewing,which are  LIGHT, VISION and OBJECT. If any omponent changes, the actual perception of colour will also change.
It is important to keep the conditions (as mentioned above) constant when viewing colors.
Colour matching requires the use of a standard light box which has several illuminants:-

 Some of the standard light sources 

  • A - tungstun

  • CWF - Cool White Fluorescent

  • TL84,  

  • UV,

  • U30
Learn about Various Light Sources
Importance of color Management
Everybody's perception of colour is slightly different. Light boxes are therefore employed so that whenever samples are viewed the conditions are exactly the same.
Color Viewing booth / light box for color matching.

It's difficult to see the true color under different light sources in which measurement color deviation intends to occur when performing the color evaluation without a standard light sources. To simulate different light sources to obtain an objective color, color difference and color evaluation, we can put the test specimen into the color viewing booth / color light box, so that it's easily to see the true color daytime, night, indoor and outdoor, and ensure the color consistency.
The Problem of Metamerism
Metamerism in textile shade matching is defined as a phenomenon in which two colored objects appear same in one light source but differ when the light source is changed. This could be due to difference in pigments or materials.
The spectral reflectance characteristics of the colors of two objects are different , but the resulting tristimulus values are same in under one light source but different in another.
Color Measurement Methods for Textile Fabrics
Color Tolerances for Consistent Pass/Fail Decisions
Every colour has a colour space which can be pinpointed by coordinates given by a computer. Colour can also be checked by eye and given a colour space, but again this is open to subjectivity.
The three fundamental aspects of colour are lightness, chroma and hue.
Lightness( bright colors,dark colors,light colors, the lightness of color changes vertically) is shown on the "L" axis. It indicates the depth of a colour, ranging from white to black with grey in between. One way of picturing depth of colour would be to imagine a black and white photograph where every colour is shown as a different depth of black, white or grey. The lightness of the fabric sample would be represented by a number on the "L" axis.
Chroma or saturation ( Vivid colors, dull colors, chroma changes outward from the center) is shown as the distance away from the "L" axis.
If the colour is described as being at the very outside edge of chroma it will appear to the observer to be very clean and bright. As it moves towards the grey central "L" axis it will become greyer, flatter and more dirty.
Hue (Redder, greener, yellower, bluer etc. hues form the color wheel) is the variation in colour. For example, a blue may be very red - moving towards purple lilac - and would appear in the blue colour space at the red side. Different shades of blue would all appear in the blue colour space but in different areas.
Lightness, chroma and hue are checked on all yarns and piece dyed fabrics to ensure colour continuity standards are maintained to the highest levels. They can be represented as a three dimensional figure.

More Information on Color Theory

A Note on Color Inconstancy
Read Book on Color Space conversions
CIE color model

Complementary colors
Electromagnetic energy
HSV color model
Light primary colors
Print primary colors
Secondary colors

Background knowledge of different light sources
CIE Fluorescent Illuminants
Artificial Daylight D65 which corresponds to a mid-day sun in Western Europe / Northern Europe is a commonly-used standard illuminant defined by the CIE. It is part of the D series of illuminants that try to portray standard illumination conditions at open-air in different parts of the world. Artificial Daylight D65 light sources do not exist actually, only simulators. The quality of a simulator can be assessed with the CIE Metamerism Index. —CIE S005/E-1998.

TL84 - CIE Fluorescent Illuminants, Light Source (F11), TL84 light sources represent a tri-band fluorescent lamp. —CIE 1931.

CWF - CIE Fluorescent Illuminants, Light Source (F2), CIE F series light sources represent various types of fluorescent lighting. CWF(Cool White Fluorescent) light sources found in office environments.

Incandescent A - CIE Incandescent A is intended to represent typical, domestic, tungsten-filament lighting. Its relative spectral power distribution is that of a Planckian radiator at a temperature of approximately 2856 K. CIE standard Incandescent A should be used in all applications of colorimetry involving the use of incandescent lighting, unless there are specific reasons for using a different illuminant. It is found in our home.

UV - UV Ultra Violet Black light to reveal the presence of fluorescent dyes and bleaches.

U30/U35 - Neutral-white fluorescents have a CCT (Correlated color temperature) of 3000K or 3500K.

Saturday, February 6, 2010

Color Fastness To Vuclanizing and phenolic Yellowing

Click The links below for Details
Color Fastness To Vuclanizing  Hot Air 
Color Fastness To Vuclanizing :-Sulphur Monochloride
Color Fastness to Vulcanizing ;- Open Steam
Phenolic Yellowing ,
New Testing Standard :-
ISO 105-X18:2007 specifies a method intended for assessment of the potential to phenolic yellowing of textile materials.
The method is specific to phenolic yellowing and does not cover the many other possible causes of yellow discolouration found on textile materials.

Textile Testing and Analysis
Issues In The Analysis And Testing Of Textile Composites With Large Representative Volume Elements
Applied basic textiles;: Raw material, construction, color, and finish, fabric analysis, chemical and physical testing of textiles, spot and stain removal, and care of clothing,

Tuesday, February 2, 2010

Mercerizing Of Knit fabrics

Tubular Knit Fabric Mercerising
The available mercerising machines are not suitable for knit fabrics due to following reasons,

  • Difference in constructional features of the fabrc.

  • Sensitivity towards the tension and stretch applications.

  • The unsuitability of usual woven cloth expanders for knitted fabrics.
Main sections of a Tubular Knit Merceriser are

  • Special entrance scaffolding suitable for knit fabrics with guide rollers

  • Impregnation compartment

  • Ring Expanders

  • Dimensional stability section

  • Fabric Straightening Section

  • Washing Section

Swastik Merceriser for Tubular Knit Fabrics For details click Here
Patchy dyeing in Mercerised Knit Fabrics :-Analysis and Corrective action
Open Width mercerizing of Knitwear :- A Study
Knitwear open concepts Knitline
Singeing Machine for Knits EcoSinge®
Machine for Knit Mercerising EcoMerc® and EcoCombine®    EcoMerce
Finishing of woven and knitted fabrics with elastane fibers Read Here
Menzel continuous merceriser
Mercerising system is to small and medium production volumes Menzel Minimerce

Fabric Mercerising Process

Mercerization, the treatment of cotton with a strong caustic alkaline solution in order to improve the luster, hand and other properties,was names after its discoverer, John Mercer.

Mercerization leads to a number of changes in fibre and fabric properties:

• a more circular fibre cross-section
• increased lustre
• increased tensile strength, a major factor for technical textile fabrics
• increased apparent colour depth after dyeing
• improved dyeability of immature cotton (greater uniformity of appearance)
• increase in fibre moisture regain
• increase in water sorption
• improved dimensional stability.

Types of mercerization

Mercerization is widely used, and in the mercerization of different kinds of cellulose products, including blended products, the machine used and the treatment conditions must be selected in accordance with the type of fiber, the form that it is in and its properties, and also in accordance with the aims and the timing of the mercerization.

The wide range of treatment methods can approximately be broken down into the following divisions. Parentheses denote established terminology.

1. Classification according to the form of the product

a) Yarn mercerization

  • Batch : Hank mercerization
  • Cheese mercerization
  • Continuous : Single end mercerization
  • Tow mercerization
  • Warp mercerization

b) Knit Mercerization

  • Open mercerization
  • Closed mercerization (Round mercerization, tubular knit mercerization)

c) Cloth mercerization

  • Chainless mercerization (Roller mercerization)
  • Chain mercerization (Stenter mercerization)
  • Batch-up mercerization

2. Classification according to the marcerizing conditions

a) Water content
  • Dry mercerization
  • Wet mercerization
b) Tension
  • Fixed-length mercerization
  • Tension mercerization
  • Tensionless mercerization
c) Alkaline concentration
  • Low-concentration alkaline mercerization
  • High-concentration alkaline mercerization
  • Two-step mercerization
d) Temperature
  • Ambient-temperature mercerization
  • High-temperature mercerization
  • Low-temperature mercerization
3. Classification according to timing
  • Gray mercerization
  • Pre-dyeing mercerization
  • Post-dyeing mercerization

4. Classification according to the number of treatments

  • Single mercerization
  • Double mercerization

5. Classification according to the type of alkali used

a. Caustic soda mercerization

b. Ammonia mercerization
Liquid ammonia treatment is a highly effective and well-controlled alternative to caustic soda mercerisation, but the high capital cost of the necessary equipment for recovery and reuse of the ammonia as well as the application step limits the adoption of this sophisticated approach more widely. The effect of liquid ammonia treatment on the dyeing of cotton depends on the way that the ammonia is removed. Aqueous washing gives a product almost as dyeable as mercerised cotton. As with mercerising, treated yarns and fabrics appear more deeply dyed than untreated material having the same amount of dye present
6. Other

a. Alkali pad-dry method
b. Alkali pad-steam method

While other variations are also used, mercerization in industry is generally implemented according to a combination of the basic factors as listed above.

Fabric Mercerising Machine
Chain Mercerizing Machines
In order to make up for the shortcomings of the roller mercerizing machine, a clip stenter is used for post-mercerization treatment, in which a widthwise tension is applied then most alkali is showered off the fabric kept on the stenter, followed by thorough alkali removal and neutralization using an open-width washing machine.
Chainless Mercerising Process
This method of mercerization running fabric through a number of rollers without the use of a clip stenter is also called roller mercerization. The machine used has a number of stainless rollers, or stainless and rubber rollers, of a relatively-large diameter tiered zigzag in close contact to each other inside a long trough, with the lower tier designed to submerge in alkaline solution for mercerization.
Cotton Fabric and Yarn mercerising process
What is mercerized cotton?
Mercerization Process Produces Quality Fabrics

Hot Mercerization
Main steps in hot mercerising process are
1. Saturation with mercerising-strength caustic soda solution at a temperature close to its boiling point
2. Controlled hot stretching for a brief dwell period
3. Controlled cooling and dilution of the caustic liquor
4. Traditional tension-controlled washing and final rinsing.
Advantages of Hot Mercerising
The main chemical and physical changes to achieve the desired improvement in fabric properties do not take place at the high temperature of the saturator but when the cooling fabric passes through the traditional caustic dilution and washing-off stages.
1. Shortening of the process sequence to provide cost savings

2. Increased efficiency and reproducibility
3. Use of chain or chainless mercerisers with fewer problems related to fabric width control
4. Improved lustre, tensile strength and dimensional stability because greater stretching of the fabric is practicable
5. Increased dye uptake at moderate tension, but excessive stretching can result in lower dyeability
6. Improved results from fabric qualities containing lower-grade cotton
7. Flash scouring effect obtained
8. Good desizing action
9. Enhanced penetration of the fibre by the hot caustic liquor.

Study of some important parameters of greig cotton after Hot mercerization
Effect of heat on mercerization
An Investigation on the Effect of Hot Mercerization on Cotton Fabrics Made up of Open-End Yarns
Effect of mercerization treatment on dimensional stability of weft knitted fabrics

Foam Mercerizing

Mercerizing strength sodium hydroxide may be foamed and this foam applied to cotton by conventional methods. Application of foamed sodium hydroxide offers the possible advantages of savings in sodium hydroxide and dyes as well as ability to treat selectively given areas of the fabric. This technology may be useful in areas other than mercerization.
The following advantages has been claimed by the experts in this area are,
1.No specialized machinery is required.
2.Less consumtion of alkali.
3.Better control of fabric dimensions
4.Preferential treatment of one face of fabric when needed.
5.Penetration of lye in pile fabrics with less lye.
6.Possibility of printing with sodium hydroxde.
7.Possibility of better coverage of dead cotton and resulting into uniform dyeing.

Slack Mercerizing :-Loose mercerizing or mercerizing without tension
Slack mercerizing is done by exhaust. The fabric is slacked and treated with NaOH solution by this process of mercerizing no  luster is obtained but absorption is increased.
Slack mercerization is different than normal mercerizimg  that it must be planned in advance and will result into a stretch fabric. Fabric to be slack mercerized  is woven with enough space left between the yarns to crimp up knowing it will be slack mercerized. Once the fabric is slack mercerized it will become tighter and narrower while at the same time giving  a permanently crimp that makes for 100% stretch cotton. It’s like giving hair a perm. It is possible to get up to 15% comfort stretch and in a twill utility stretch.

Technology highlights of Goller Mercerizing Machine

 Watch video of knit mercerizing here

Monday, February 1, 2010

Gas Singeing Machines

Singeing is a finishing method for smoothing surfaces of fabrics by burning and removing fuzz thereon, and visualizing fabric textures. A gas-singeing machine is normally employed.
The gas-singeing machine is typically equipped with four burners, and is capable of singeing one or both surfaces of the fabrics. A water-cooled roller is provided at a location opposite to the burners, thereby enabling singeing to be performed without undermining the strength of even thin fabrics. It is important to set a drain temperature of the water-cooled roller in a range of 50 to 550C. Cautions are required because a dew-point is generated when the water-cooled roller is cooled down too much, and results in increased amount of remaining fuzz or adhered carbon. The fabric feed speed is preferably set at around 100 to 150m/minute.

Swastika Gas Singeing Machine
Textile Wet Processes: Preparation of Fibers and Fabrics

Rotary Cylinder Singeing Machines

In this type of singeing machine, the cloth passes over and in contact with a heated rotary cylinder made of copper or cast iron. The rotary cylinder has internal firing and revolves slowly so that constantly a fresh surface of the roller comes in contact with the cloth. The direction of rotation of the cylinder is opposite to the direction of the fabric so that the protruding fibres or nap of the fabric is raised.
This type of machine is particularly suitable for the singeing of velvets and other pile fabrics.
If the singeing of both sides of the fabric is required, then two cylinder are employed, one for each side of the fabric.
Singeing of Knitted Goods
Because knitted fabrics are very sensitive to tension , it is therefore necessary to take special care in singeing. Important control factors in knit singeing are
  • Appropriate Singeing temperature for the particular fiber compositon.
  • Tension control at fabric entry, fabric run and fabric delivery.
  • The machines should have tension controls throughout the fabric passage. 
Gas Singeing Process and machines
Singeing Fundamentals

Plate Singeing Machines

Plate Singeing Machine

In this type of singeing machine, the cloth passes over and in contact with one or two heated curved copper plates. The thickness of the plates ranges from 1 to 2 inches. The heating of the plates is done by a suitable burning arrangement of gas mixed with air. The plates are heated to bright redness and the cloth passes over and in contact with these plates at a speed ranging from 150 to 250 yards per minute.
The passage of the cloth can be arranged in such a manner that one or both sides of the fabric may pass over and in contact with the heated plate(s), in order to accomplish singeing of one or both sides of the fabric in a single passage.
In order to avoid local cooling of a certain part of the plate(s) by constant passage of cloth over it, an automatic traversing mechanism is fitted to the machine. This mechanism brings the cloth into contact with a constantly changing part of the plate(s), not only to avoid local cooling but also local wearing of the plate(s).


Textile wet processing :- E Learning

 Introduction to textile Wet Processing
 Click Here
Textile Preparation
          1) Plate Singeing Machine.
          2) Rotary Singing Machine.
          3) Gas Singeing Machine.
  1. Dyeing Methods
  • Fiber Dyeing
  • Yarn Dyeing
  • Piece Dyeing
  • Rope Dyeing
  • Open width Dyeing
  • Garment Dyeing

2. Dye Classes
Quality Control and Color Measurement
 3. Dyeing machines
      HTHP Package dyeing machines
Hank Dyeing Machines
Rope Dyeing Machines
Open Width Dyeing Machines
Garment Dyeing Machines
Printing of Textile Materials
      Printing Process
  • Preparation of print paste
  • Printing of fabric
  • Drying
  • Fixation of dyestuff
  • Washing – off
Printing Methods
  • Flat Bed Screen Printing
  • Rotary Screen Printing
  • Heat Transfer Printing
  • Digital Inkjet Printing
  • Resist Printing
  • Discharge Printing
  • Flock Printing
  • Other Printing Methods
  • A Handbook of Garment Dyeing and Cleaning

Finishing is the final series of operations that produces finished textile fabric from greige goods. Finishing operations are predominantly wet operations requiring large amounts of thermal energy for water heating and drying.
Chemical Finishing
  • Optical Finishes
  • Resin Finish
  • Absorbent and Soil Release
  • Softening and abrasion Resistance finishes
  • Water repellent
  • Oil repellent
  • Flame retarding
  • Bio Finishing
  • Anti Microbial Finishing
  • Stiffening and weighing
  • Laminating
  • Plasma treatments
  • Anti mildew Treatment
  • Enzyme Treatments
Mechanical Finishing
  • Heat Setting
  • Raising
  • Shearing
  • Calendering
  • Decating
  • Sanforising
  • Compacting
  • Brushing and Napping
  • Embossing
  • Sueding
Energy Management In Textile Wet Processing
Environmental Management System in Textile Wet Processing
Water and Waste Water in Textiel Wet processing
Health and Safety In Textile Wet Processing