Greige Fabric Inspection

Greige/Gray/Grey Fabric

Newly constructed fabric as it comes from the mill is called as greige fabric

The goods must pass through various processes to make it suitable for its intended use

GREY ROOM OPERATIONS

Fabric inspection involves following three processesPerchingBurlingMending

GREY ROOM OPERATIONSPerching It is a visual inspection and it is carried out through the inspection table which consists of a frosted glass with lights behind and above it.

The fabric imperfections like thick places, defects, yarn knots, stains and other flaws are marked.

Burling It is the removal of yarn knots or other imperfection from the fabric.

GREY ROOM OPERATIONSMending is the actual repair of imperfections.

The recent innovation by the use of laser beams. The imperfections like stains, holes, thick places, loose ends and protruding threads of warp and weft are detected.

Eliminates human error. Sewing: After the goods have been inspected, checked and classed in the grey room, according to quality and stamped, they are sewn together, end to end, by sewing machines

Fabric Inspection

PrincipleImportanceTypes of InspectionRequirements Inspection Systems

Fabric Defects

Minor, Major and SeriousWoven & Knitted

Defects

Major Defect:

A defect that, if conspicuous (clearly visible) on the finished product, would cause the item to be a second.

A "second" is a garment with a conspicuous defect that affects the sale-ability or service-ability of the item.

Minor Defect:

A defect that would not cause the product to be termed a second either because of severity or location.

WOVEN FABRIC DEFECTSJerk-in (major/minor) - Caused by an extra piece of filling yarn being jerked part way into the fabric by the shuttle. The defect will appear at the selvedge Knots (minor) - Caused by tying of yarns together. Burl Mark (major) - extra piece of yarn is woven into the fabric Drawbacks (major) - Caused by excessive loom tension applied by some abnormal restriction. When the restriction is removed the excess slack is woven into the fabric. Usually the ends are broken Dropped Pick (major) - Caused by the filling insertion mechanism on a shuttle-less loom not holding the filling yarn, causing the filling yarn to be woven without tension.

End Out (major) - Caused by yarn breaking and loom continuing to run with missing end

Mixed End (major) - Yarn of a different fiber blend used on the warp frame, resulting in a streak in the fabric

Mixed Filling (major) - Caused by bobbin of lightweight yarn or different fiber blend used in filling. Will appear as a distinct shade/color change Open Reed (major) - Results from a bent reed wire causing warp ends to be held apart, exposing the filling yarn. Slub (major/minor) - Usually caused by an extra piece of yarn that is woven into fabric. It can also be caused by thick places in the yarn. Often caused by fly waste being spun in yarn in the spinning process

Smash (major) - Caused by a number of ruptured warp ends that have been repaired

Soiled Filling or End (major) - Dirty, oil looking spots on the warp or filling yarns, or on package-dyed yarn

Stop Mark (major/minor) - When the loom is stopped, the yarn elongates under tension; when loom starts again the slackness is woven into the fabric Thin Place (major) - Often caused by the filling yarn breaking and the loom continuing to run until the operator notices the problem

Barre (major) - Caused by mixing yarn on feed into machine. Fabric will appear to have horizontal streaks

Birdseye (major/minor) - Caused by unintentional tucking from malfunctioning needle. Usually two small distorted stitches, side by side

Broken Color Pattern (major) - Usually caused by colored yarn on frame.

Drop Stitches (major) - Results from malfunctioning needle or jack. Will appear as holes or missing stitches.

End Out (major) - Results from knitting machine continuing to run with missing endKNITTED FABRIC DEFECTS

Hole (major) - Caused by broken needle Missing Yarn (major) - Caused by one end of yarn missing from feed and machine continuing to run Mixed Yarn (major) - Results from wrong yarn (or wrong size yarn) placed on feed. Fabric could appear as thick end or different color if fibers have different affinity for dye Needle Line (major/minor) - Caused by bent needle forming distorted stitches. Usually vertical line

Press-Off (major) - Results when all or some of the needles on circular knitting fail to function and fabric either falls off the machine or design is completely disrupted or destroyed. Runner (major) - Caused by broken needle. Will appear as vertical line. Most machines have a stopping device to stop machine when a needle breaks Slub (major/minor) - Usually caused by a thick or heavy place in yarn, or by lint getting onto yarn feeds.

Inspection

PRINCIPLEInspectionDetection of defectsFeedback of these defects to appropriate personnelDetermination of causes of defectsCorrection of the defects

IMPORTANCEFabric inspection is done to determine its acceptability.If inspection is not done, it may result in Loss of the materialLoss of timeDissatisfaction due to poor qualityPoor customer return

InspectionInspection is carried out mainly to appraise the quality of products in terms of manufacturing defects and adherence to the specifications and other requirements.

Normally, the visual inspection is carried out on the fabric to examine the occurrence of yarn defects, fabric defects, design/colors besides specification particulars.

In the earlier days, the inspection was mainly carried out to segregate the defective products from the good products thereby controlling the quality of products at the exit points.

Types of InspectionThere are two ways of doing inspection viz. 100% inspection and sampling inspection.

The 100% inspection is generally carried out to segregate the products quality-wise and perform mending activity for products having mendable defects whereas the sampling inspection mainly focus on sentencing the lot or batch for acceptance or otherwise based on the sample.

This will lead to reduction in defects in the final product, rejection level, replacement and thereby improve the quality of the final product which results in quality image in the market

Requirements of Inspection

Inspection and Mending is to be carried out on a flat table in a well illuminated/ ventilated place.

Inspection equipments/tools: counting glass, a good calibrated measuring tape, metallic comb, clipper/plucker needle.

CHECKING OF DIMENSIONSMEASUREMENT OF WIDTH:Width shall be measured at three different places of the fabric and recorded.

While measuring width, care should be taken

to remove the wrinkles/ crease gently from the fabric surface.to keep the measuring tape straight across the fabric horizontally from selvedge to selvedge.to measure the width as far as possible near the center avoiding the ends.not to stretch the fabric while measuring.

MEASUREMENT OF LENGTH:

Length is measured by any of the following methods

By passing through metre counter fitted roller.By manually clipping the fabrics in the fold measuring frame.By counting the number of metre fold in case of folded fabrics.

Care to be taken to ensure that the folds are of one metre length by measuring a few folds.

CHECKING OF CONSTRUCTIONALPARTICULARSENDS PER INCH:Ends per inch shall be counted at two places along the width of the fabric and recorded.

PICKS PER INCH:Picks per inch shall be counted at three places along the length of the fabric and recorded.

Care to be taken while placing the pick glass to see that the edges of the template should coincide with the yarn. Ends/Picks per inch may be counted for one inch. Also the picks should not be counted at defective places like weft bars and cracks.

WEIGHT PER SQ.MTR.:Pieces are to be weighed and recorded. Weight per square metre to be calculated and recorded.CALCULATION OF WEIGHT/SQ.MTR.:Weigh the individual piece under Inspection and note-down.Work out the sq.mtrs. of the piece by multiplying the length of the piece in mtrs. and width of the piece in mtrs.Calculate wt./sq.mtrs . as:Weight in kgs.---------------------------------------------------Length in mtrs. X Width in mtrs.

Inspection SystemsThere are three different systems for grading the quality of fabric, which are as follows:SYSTEM . I (FLAW BASED)In this system, depending upon the magnitude, defects are classified as minor, major or serious.Note:Minor Flaws:

Minor flaws occurring more than one in number within 15 cms. length of the cloth shall be reckoned as one minor flaw only

2) Major Flaws:

Major flaws occurring more than one in number within a length of 15 cms. of the cloth shall be reckoned as one major flaw only.

Major flaws occurring in a consecutive length beyond 15 cms. shall be reckoned as one major flaw each for every 15 cms. or part thereof.

3) Selvedge Defects:

In case of furnishing fabrics all selvedge defects like pulled in selvedge, wavy selvedge etc. of minor nature are also to be reckoned as major flaws.

Defective or damaged selvedge exceeding 5% of the length of the piece in case of furnishing fabrics are to be reckoned as serious flaw.

All types of selvedge defects or weaving defects very close to the selvedges are not to be reckoned in case of fabrics used for making garments/made-ups.

ACCEPTABILITY CRITERIA FOR FLAWS:The acceptability level for first quality fabric is usually established by mutual agreement between the buyer and the seller.

The different types of fabrics have different point levels of acceptability depending upon their end use.

Some of the commonly followed standard for acceptability for the above mentioned systems are listed here

Note:Minor flaws : @ 25 per 100 meters maximum are acceptable.Serious flaws: No serious flaw is acceptable.

Sample size (m)Acceptd no. of major flawsSample size (m)Acceptd no. of major flaws

Standard.A-1Standard AStandard.A-1Standard A

1200294035071011752839325691150273830068112526372755711002636250461075253522546105025342003510252433175341000233215023975233112523950223110012

SYSTEM . II (4-POINT SYSTEM)

The 4-point system, also called the American Apparel Manufacturers Association (AAMA) point grading system for determining fabric quality, is widely used by producers of apparel fabrics and by the Department of Defence in the United States

Fabric flaws or defects are assigned point values based on the following:

Length of defect in fabric, either length or width Points allotted

Up to 3 in. (7.5 cms.) 1Over 3 in. (7.5 cms.) up to 6 in (15 cms.)2Over 6 in. (15 cms.) up to 9 in. (23 cms.) 3Over 9 in. (23 cms.)4Holes and openings(largest dimension)Points allotted

1 in. (2.5 cms.) or less 2Over 1 in. (2.5 cms.)4

The maximum number of defect points to be counted against any one linear yard/metre is four points. Overall, fabric quality is assessed on the basis of the number of defect points per 100 sq yards/sq mtrs. of fabric.

ACCEPTABILITY CRITERIA FOR FLAWS:

Normally fabric rolls containing up to 40 points per 100 sq yds. and 48 points per 100 sq mtrs. are acceptable.

However, based on the price line and end product more or less than 40/48 points per 100 sq. yds./100 sq mtrs. respectively may be accepted.

Example - 1A fabric roll of 120 yds. long and 48 in. wide contains the following defects:

2 defects up to 3 in. 5 defects over 3 in. but less than 6 in. 1 defects over 6 in. but less than 9 in. 1 defect over 9 in.

Points/100 sq. yds

Total points scored in the roll=---------------------------------------------------Fabric width x Total yard inspected

Answer??????????????????????????????????????

2 defects up to 3 in. 2 x 1 = 2 points5 defects over 3 in. but less than 6 in. 5 x 2 = 10 points1 defects over 6 in. but less than 9 in. 1 x 3 = 3 points1 defect over 9 in. 1 x 4 = 4 points

TOTAL =19 points

Therefore, Points/100 sq. yds.Total points scored in the roll x 3600=---------------------------------------------------Fabric width in inches x Total yard inspected

19 x 3600= --------------- 48 x 120

= 11.9 defect points/100 sq. yds.

So if the acceptance criteria is 40 points/100 sq. yds. then this roll is acceptable.

Example - 2:A fabric roll of 100 m long and 150 cm wide contains the following defects:

3 defects up to 7.5 cm. 6 defects over 7.5 cm. but less than 15 cm.2 defects over 15 cm but less than 23 cm.1 defect over 23 cm.

Answer?????????????????????????????

SYSTEM . III (10-POINT SYSTEM)No linear yard of fabric is assigned more than 10 points, no matter how bad or frequent the defects are.

Acceptability criteria for flaws:

Fabric is considered of first quality if the number of defect points are less than the number of yards of fabric inspected.

In the case of fabrics wider than 50 in., the fabric is considered of first quality if the total defect points do not exceed the number of yards of fabric inspected by 10%.

Length of defect, Warp defectsPoints allottedUp to1 inch11 to 5 inch 35 to 10 inch 510 to 36 inch 10Filling defect (weft defect)Points allotted

Up to 1 inch11 to 5 inch35 inch to half-width5Larger than half-width10

Fabric Pre-Treatment

Series of cleaning processes/steps/operations that make the fabric fit for the preceding/subsequent process e.g. Dyeing or Printing or Finishing

Improper preparation is often the cause of problems encountered in the dyeing and finishing steps

Preparation ProcessesColoration processesFinishing ProcessesTo ensure that textiles has the right physical and chemical properties for subsequent operationsTo provide the textile with color for aesthetic or functional purposeTo provide textile with properties that end-use demands and that have not been provided already by earlier processesExamples:ScouringBleachingHeat SettingExamples:DyeingPrintingExamples:Water RepellencyFlame RetardencyAnti-soiling Finish

PREPARATORY OPERATIONSThe main objectives:Removes all impurities from the fiber, both naturals and / or those added during production that may interfere in subsequent dyeing and / or finishing process.Improve the ability of the fibers to absorb water solutions of dyes and chemicals.Impart the proper brightness or whiteness to fabrics according to need, especially when brilliant or certain pastel shades are desired.

The most effective and widely used method

Chemically enzymes are proteins of high molecular weights.

Amylases are the enzymes used in de-sizing.

They are two categories namely -amylase and - amylase

These enzymes can be derived from sources like animal (pancreatic) and vegetable (malt and bacterial)

Enzymes & Condition for De-sizing

S.NoAmylase EnzymeConc. gplTemp CpH1Malt5 - 2050 -606 7.52Pancreatic1 - 350 -606.5 7.5

3Bacterial0.5 - 160 -705.5 7.5

This is the oldest and cheapest method because no chemical is used in this treatment.

The fabric is soaked in warm water and at 35 40C temperature and passed through a padding mangle and squeezed.

It is allowed to stand for 24 hrs.

During the storage the bacterial growth takes place, which helps effective removal of starch materials.

After that hot washed.

Rot Steeping

Advantages: Most economical and simplest processDisadvantages: Time consuming Unevenness in de-sizing No control over the process

In this method, dilute hydro chloric acid or sulphuric acid or a mixture of both are used to hydrolyze the starch from the sized fabric.

The fabric is steeped in 0.25% (10 gpl) of the acid, passed through padding mangle and kept for 6 hrs at temperature 50C.

The starch present in the fabric is liquefied and is easily removed by washing.

Since, acid can attack cellulose, care have to be taken to avoid damage of cotton.

The fabric should be washed with hot water after de-sizing. Acid Steeping

Advantage: The time consumption is reduced compare with rot steeping

Disadvantage: There is no control over the process.

Oxidative De-sizingIn this process starch is oxidized. The commonly used oxidative de-sizing agents are Hydrogen per oxide Sodium bromide. Ammonium per sulphate

Hydrogen peroxide of 1-2 volume concentration & caustic soda (7-15 gpl ) is prepared in padder

The cloth is first impregnated at room temperature and steamed for 3 minutes.

Advantages Time required is less and the process is continuous. Water and energy consumption is less Combination with other preparatory process such as scouring and bleaching is possible Excellent & uniform removal of size Disadvantages There may be possibilities of penta-chloro phenol content in the de-sized fabric that may be harmful.Expensive process

Synthetic detergents are now being increasingly used in place of soap.

Their main advantage is that they permit continuos processing of piece goods and the time of treatment is shorter by 40 minutes.

In this method, the material is treated with 2.5 to 5 g/l detergent (Sandopan SRS liq. of Sandoz) at pH 11.2 to 11.5 for 30 to 60 minutes at boil, then rinsed thoroughly first with hot water and then with cold water.

The disadvantage of this method is that soft feel is not always obtained.

Degumming with Synthetic Detergents

Degumming with EnzymesTreatment with some protein enzymes like trypsin or papain may dissolve the sericin gum. The treatment is time consuming and involves three step process.This treatment is longer than that with synthetic detergents I Step: The material is first treated with 0.5 g/l soda ash ; 0.5 g/l Glaubers salt ; 3 g/l penetrating agent like Imerol XN liq. (Sandoz); at boil for about 1 hour.

II Step: It is then treated with 1-5 gpl sericin dissolving enzyme(trypsin or papain),1gpl soda ash, 2gpl Glauber's salt at 450C.

III Step: The above material is treated in the 3rd bath with 0.5gpl soda ash, 2gpl sodium silicate, 2gpl penetrating agent and 0.5gpl Glauber's salt at boil for one hour.

The reaction takeing place during scouring :-

Oils, waxes and free fatty acids are emulsified by the soaps

Pectin's are converted into soluble salts

Proteins are degraded to simple soluble amino acids and mineral matter is dissolved

Dirt is removed and other added impurities are broken into soluble products

Scouring of woolImpurities present in wool are animal fat, suint (dried perspiration) dirt and mineral matter.

Animal fat is a wax which can be removed by the formation of emulsion with alkali.

Suint is soluble in water

The dirt and sand in the wool are removed during scouring by mechanical agitation

CLEANING OF WOOLThe technique consists of passing wool fibres through a series of four long narrow bowls containing soap or non-ionic synthetic detergents and sodium carbonate at a temperature of 40-550 C.

DetergentSoda ashpHTemperature1-bowl0.25%0.25%9-1048-520C.2-bowl0.2%----1046-500C.3-bowl0.1%-------43-460C.4-bowlFresh water wash alone40-450C.

KIER BOILING A kier is a cylindrical vessel capable of holding 250 to 5000 kgs of fabric. It is provided with temperature, pressure gauge and safety valve.

For kier boiling, a mixture of 5-10 g/l caustic soda solution, 1% sodium silicate, 1% soap along with wetting agent.

The circulation of hot alkaline liquor through the fabric is carried out under pressure ( at 25-30 psi and 130-135 C) for period of 6-12 hrs, depending on the type of fabric.

In atmospheric scouring process (open kiering) ---- at 95-98C for 4-6 hrs

After that hot and cold washes are given to complete the process.

J-Box - CONTINUOUS SCOURING In continuous machines, scouring can be carried out through a series of J-Boxes for progressive de-sizing and scouring.

The de-sized and washed fabric is padded with strong alkali solution (5-10 gm/lit NaOH or mixture of NaOH & sodium carbonate), emulsifying agent and wetting agent.

J-Box CONTINUOUS SCOURING After padding the saturated cloth, it enters in to J-Box where it remains for 40-60 min in plaited form at a temperature of about 100C.

The cloth before entering J-Box is rapidly preheated by means of steam in U- shaped heating tube.

The internal surface of the entire J-Box is very smooth to avoid any friction on the moving cloth.

Oxidizing Bleaching agents:Sodium hypo chlorite, Sodium chlorite, sodium per borate, sodium per corbonate.

Advantages of bleaching with hydrogen peroxide :Hydrogen per oxide is a universal and is used extensively for the bleaching of cotton materials.

Hydrogen peroxide. Universal bleaching agent Almost all cotton, silk, wool ; polyester/cotton blends are bleached with hydrogen peroxide.

It can be employed for bleaching fibers like wool, silk, polyester and other man- made fibers also, under a wide range of application conditions.

It requires less manipulation of fabric and hence less labor.

Advantages of bleaching with hydrogen peroxide :The loss in weight of fabric in bleaching is less than that with hypochlorite bleaching.

Per oxide bleached are more absorbent than hypochlorite bleached fabrics.

No possibilities of yellowing of fabric.Continued.

The yarn or cloth after scouring is thoroughly washed before bleaching and is squeezed or hydro extracted to remove excess of water as otherwise it would dilute the bleach liquor (chemicking)

Since the bleaching is done in alkaline medium (pH 10-11) the alkali, which is present in the material has to be neutralized with dilute mineral acid. It is referred as souringSodium hypochlorite Bleaching:

Sodium hypochlorite Bleaching:

ADVANTAGESDISADVANTAGESPowerful and economical method of processingExcessive chlorine may cause pollution

Free from the defects of bleaching powderAll protein impurities must be completely removed before bleaching otherwise the fabric may turns yellowishResidual chlorine must be removed.

Sodium hypochlorite Bleaching: To remove the residual chlorine, the fabric is to be washed with sodium thio - sulphate (chlorine destroyer) or hydrogen peroxide (weak solution) the chlorine will wash away.

This treatment is called antichlor

Types of BleachesFull-BleachIt is done generally when highest degree of whiteness is required and going to be used as a white fabric for apparels or to be printed with white background.This is achieved by bleaching with hypochlorite followed by hydrogen peroxide bleach.Half-BleachIt is done for fabrics meant for dyeing and printing where more absorbency is required than the whiteness and fabrics going to be used during finishing.This is generally done using by bleaching with hypochlorite or hydrogen peroxide of adequate concentration.

BLEACHING CONTINOUS BLEACHING PROCESS:In this process de-sizing, scouring and bleaching are combined together. These are very attractive options since savings in time, energy, labor, etc., are possible.

In this method, the fabric is padded with the enzyme bath and then passed into a wet steam chamber at 960C- 1000C where the desizing takes place in less than a minute.

The fabric after desizing is impregnated in a solution of 4-6% NaOH, 1-3 g/l wetting agent, and 1-3 g/l emulsifier at the period of 2-3 minutes.

BLEACHING CONTINOUS BLEACHING PROCESS:J- B0X

The fabric after impregnation is taken out and piled into J-box at 980C and allowed to remain there for two hours during which period the alkali reacts with the impurities.

The fabric is then rinsed and impregnated with 1% hydrogen peroxide at pH 10.5-using1% sodium silicate as a stabilizer and wetting agent.

The cloth after impregnation is again heated to 90-95C and stored for an hour in J- box.

It is then rinsed thoroughly.

OPTICAL BRIGHTENERS- fluorescent whiteners (FWA)The purpose is to obtain extraordinary brilliant whiteness to cotton materials. Optical brighteners acts as fluorescent dyes and they are colorless

They absorb light near to ultraviolet region ( below 400nm) and re-emit the light in the violet blue visible region.

Near white bleached cloth, possesses a yellowness caused by absorption in the blue region.

When FWA is applied, the blue florescence compliments the yellowness and adds a bluish hue to the fabrics, which the eye appreciates as brilliant white.

Hue is one of the main properties of a color, defined technically, as "the degree to which a stimulus can be described as similar to or different from stimuli that are described as red, green, blue, and yellow,"

OPTICAL BRIGHTENERSApplication of Optical Brighteners:The application of optical brighteners depends on the types of fibres. classified as direct, disperse and cationic types. The direct brightening agents are mainly used for the brightening of cotton, linen, viscose and nylon materials. The acid florescent brightening agents serve mainly for the brightening of silk and wool fabrics. The disperse florescent brightening agents are used primarily for polyester, acetate and acrylic materials.

Definition:The treatment of cotton fabrics or yarns with a cold concentrated solution of Sodium hydroxide solution for one minute or less is called mercerization.

MERCERIZATION

Internal reorientation of cellulose structure modifiedStrength is increased to 15-25%; It also improves elasticity and dimensional stabilityLuster and feel further enhanced; It also improves absorbency of water, dyes and other finishing chemicals.Increases the uniformity of dyeing and improvising the color yield by increasing the dye affinity, resulting enhanced color fastness & saving in cost of dyestuffsMercerization improves the following properties :MERCERIZATION

Fabric is padded with about 20-25% NaOH solution containing a wetting agent. Passed over several cans to allow a dwelling time of approximately one minute. During this time NaOH will penetrate the fibers and react with them. Mercerization Process :MERCERIZATION

At this stage the tension is applied lengthwise. The fabric is then placed on a tenter frame and is pulled to its desired dimensions (Tension is applied in both the warp and filling direction). While on the tenter frame, the fabric is washed by spraying water until the concentration of Sodium Hydroxide is reduced to less percent.Then the fabric is washed by passing through several washers, one of which contains a diluted sulphuric acid or acetic acid.Continued.Mercerization Process :MERCERIZATION