US3290752A

US3290752A - Woven cotton-polyester blend fabrics having recoverable stretch characteristics

Info

Publication number: US3290752A
Application number: US267932A
Authority: US
Inventors: Harry W Ormand
Original assignee: Thomaston Cotton Mills
Current assignee: Thomaston Cotton Mills
Priority date: 1963-03-26
Filing date: 1963-03-26
Publication date: 1966-12-13
Anticipated expiration: 1983-12-13
Also published as: LU45613A1; GB1028020A; BE644898A; NL6401658A; CH378064A4

Description

Dec. 13, 1966 w QRMAND 3,290,752 WOVEN COTTON-POLYESTER BLEND FABRICS HAVING RECOVERABLE STRETCH CHARACTERISTICS Filed March 26, 196:5

WOVEN FABRIC CONSISTING OF BLEND OF COTTON AND POLYESTER FIBER DESIZE FABRIC WET FABRIC WITH MERCERIZING SOLUTION 0E SODIUM HYDROXIDE SHRINK FABRIC IN FILLING DIRECTION BY ACTION 0}? MERCERIZING AGENT WHILE SUBSTANTIALLY UNTENSIONED IN FILLING DIRECTION BUT MAINTAINING TENSION IN WARPWISE DIRECTION WASH FABRIC WITH TENSION IN WARPWISE DIRECTION BUT WITHOUT TENSION INEILLLNG DIRECTION AND DRY WITHOUT STRETCHING IN FILLING DIRECTION IMPREGNATE FABRIC WITH A LIQUID MIXTURE OF FLUORESCENT DYE AND WETTING AGENT, AND DRY WHILE RESTRICTING SHRINKAGE IN FILLING DIRECT ION HEAT DRIED FABRIC TO SHRINKAND STABILIZE POLYESTER FIBERS OFFILLING YARNS WHILE MAINTAINING FABRIC UNDER TENSION IN WARPWISE DIRECTION BUT WITHOUT TENSION IN FILLING DIRECTION IMPREGNATE. FABRIC WITH LIQUID MIXTURE OF SOFTENER AND PIGMENT AND DRY WHILE CONTROLLING WIDTH SUBJECT FABRIC TO COMPRESSIVE SHRINKAGE OPERATION '10 CONTROL RESIDUAL SHRINKAGE INVENTOR HARRY W. ORMAND ATTORNEYS United States Patent 3,290,752 WOVEN COTTON-POLYESTER BLEND FABRICS HAVING RECOVERABLE STRETCH CHARAC- TERISTICS Harry W. Ormand, Upson County, Ga., assignor to Thomaston Cotton Mills, Thomaston, Ga., a corporation of Georgia Filed Mar. 26, 1963, Ser. No. 267,932 5 Claims. (Cl. 28--74) This invention relates to woven fabrics comprising blends of cotton and synthetic fibers having recoverable stretch characteristics, and is particularly directed to the production of cotton-polyester blend fabrics woven from standard or normal twist yarns which have desirable stretch properties in the filling direction.

A primary object of the invention is to provide a simple but elfective process for manufacturing woven cottonpolyester blend fabrics whereby stabilized width stretch characteristics are embodied therein by a novelcombination of mechanical and chemical treating steps Without using stretch or textured yarns, and without requiring special machinery.

Another object is the provision of a new and economical method for producing fabrics woven of cotton and polyester fibers having high stretch and recovery properties in the filling direction wherein only standard or normal twist yarns are employed.

A further object is to produce woven cotton-synthetic blend fabrics of improved stretch characteristics which.

are especially well adapted for end use in the apparel field, for such items as shirts, pajamas, brassiere fabrics, outerwear, underwear, lounge wear, sportswear, foundation garments, shoes, bathing suits and coating for rainwear, and for such industrial end uses as the manufacture of vinyl, rubber, pyroxylin and polyurethane coated or laminated textile materials, where resiliency in one direction is-an important consumer quality.

In accordance with the present invention, woven cotton and polyester blend fabrics having a stretch of from 15% to 30% in the width can be produced simply and economically, using conventional finishing machinery, by a novel combination of chemical and mechanical treating steps including mercerizingwithout widthwise tension, Washing in open width washers, drying without increasing the width of the fabric, treating with a resin or other chemical agent so as to stabilize the cotton fibers, or, alternatively, heat setting to shrink and stabilize the polyester fibers;v and compressively shrinking the fabric to control the residual shrinkage. In addition to these principal steps, the process may include various other operati-ons as will appear more fully'from the examples herein after described.

The process of the invention is applicable to all woven cotton-polyester blend fabrics made from standard or normal twist yarns, including reeded out or redesigned constructions as well as standard greige constructions of various types and weights. The product of the invention is a woven cotton-synthetic fabric having a high degree of stretchab'ility and elastic recovery in the filling direction while being relatively unstretchable in the warp direction, and is useful for a wide variety of end uses either per se or as a backing for or lamina with such other materials as vinyl plastic and rubber sheeting, polyurethane foams, pyroxylin artificial leather and the like.

I have discovered that woven cotton-polyester blend fabrics of high width stretch and low set characteristics can be produced by shrinking a desized greige or bleached fabric in the filling direction by subjecting it to the action of a mercerizing agent without widthwise restraint while maintaining it under tension in. a lengthwise direction,

thereafter washing the fabric until substantially all of the mercerizing agent has been removed, again without applying tension in the filling direction, drying the washed fabric without stretching widthwise, impregnating the dried fabric with a thermosetting resin or other suitable cross linking agent and curing the resin so as to maintain the cotton fibers of the fabric in resilient or elastic condition in the Width, washing the resin treated fabric with a suitable detergent to remove any unfixed resin or other free chemicals, drying, top softening the dried fabric and then again drying on a tenter frame, and finally shrinking the fabric on a compressive shrinking machine so as to control the residual shrinkage and produce the desired finished width. I have also found that similar high width stretch and low set characteristics can be obtained by substituting for the resin treatment, which affects only the cotton fibers of the fabric, a heat setting operation which affects only the polyester fibers.

The term low set characteristic as used herein has reference to that characteristic of the fabrics of the present invention which is represented by the ability of the fabric to undergo repeated stretching without suffering more than a relatively small amount of permanent elongation in the stretched direction. In other words, low set is the equivalent of high recovery. A method of measuring the set of stretch fabric is described hereinafter in connection with Example I.

The desired results may be effectively obtained by a process which includes the following steps. First, after a cotton-polyester blend fabric of suitable construction and weight, such as a 50% cotton and 50% Kodel blend, has been desized, scoured, bleached, singed and dried, it is impregnated with an aqueous solution of sodium hydroxide of mercerizing strength, a solution having a specific gravity of from 52 to 54 Twad. being preferred, and is then advanced through a mercerizing range under warpwise tension but free from tension in the filling direction and without using water on the tenter frame. The fabric is thus free to shrink widthwise under the effect of the mercerizing solution and as a result of the lengthwisetension which is maintained to prevent shrinkage in the warp direction. After the fabric has been saturated with the mercerizing solution, it is washed with water to remove the sodium hydroxide while tensioned in the warp direction but again left slack in the filling direction, the washing preferably being carried out by advancing the fabric through a plurality of open width washers, using water of any suitable temperature. Ordinarily hot water having a temperature of from about 160 to about 180 F. is used in all but the last washer wherein cold water is used. If desired, a small amount of acid may be added to the water in the next to the last Washer in order to neutralize any of the caustic soda which may remain in the fabric. After the washing operation, the fabric is dried in a revolving drum or can type drier without increasing the width thereof while still applying tension in a warpwise direction.

Alternatively, in the event that the widthwise shrinkage due to chemical action is to be accurately limited to a predetermined amount, the selvages of the fabric may be attached to the appropriately adjusted pins or clips of the mercerizing tenter frame during passage therethrough so that the fabric may not shrink more than the desired amount. Normally, however, the method of the present invention contemplates the maximum possible shrinkage of the fabric in the filling direction, i.e., up to about 30%, the amount of shrinkage being controlled by both the strength of the mercerizing solution andthe lengthwise tension applied to the fabric.

Instead of impregnating the fabric with sodium hydroxide on a conventional mercerizing range as above described, this step of the method may be carried out by passing the fabric in a slack width condition through a suitable padding apparatus equipped with a saturating box and then winding the goods on a roll under lengthwise tension for a suitable period of storage before the washing step.

After the fabric has been slack mercerized, washed and dried, it is chemically treated with a cross linking agent in order to stabilize the width stretch properties then possessed by the cotton fibers of the goods as a result of the abnormal shrinkage previously produced. For this purpose, the fabric may be first treated with an anionic wetting agent and then impregnated with a suitable thermosetting resin and catalyst, dried without increasing the width thereof, and subjected to an elevated temperature of such amount, and for such a period of time, as will effect proper curing of the resin. Triazine or triazone resins and buffered inorganic salt catalysts, such as magnesium chloride, are preferred, in which event curing at a temperature of from 320 to 340 F. for a period of from one to three minutes will normally sufiice. Alternatively, the resin may be replaced by a non-resin cross linking agent, such as formaldehyde, divinyl sulfone, and other known chemicals having the capacity to react with and cross link the cellulose molecules of cotton fibers.

Following the cross linking treatment, the fabric is soaped or washed with a detergent of any suitable composition in order to remove excess chemicals which may remain from the preceding steps, dried, top softened by passage through a mix containing suitable softeners, lubricants and a vat pigment, and then dried on a tenter frame. After this last drying step, the fabric is shrunk on a compressive shrinking machine to provide a 1% residual shrinkage in the length and sufficient shrinkage in the width to produce the desired finished width.

When processing certain types of cotton-polyester blend fabrics, such as a blend of 35% cotton and 65% Dacron, it may be desirable to omit the cross linking treatment and instead subject the fabric to a heat setting operation. In this modification of the process, after the fabric has been mercerized, washed and dried, it is padded through a bluing mix containing a fluorescent dye and then dried by passage through a tenter frame equipped with a drying system under lengthwise tension but without any tension in the filling direction, or with a width setting which is from 2 to 3" greater than the desired finished width of the goods. From the drying tenter frame, the fabric is passed through a heat setting oven at such a temperature and speed of travel as to shrink and stabilize the polyester fibers of the fabric. Following the heat setting operation, the goods are treated with softeners, lubricants and dyes of any suitable character, dried, and finally shrunk on a compressive shrinking machine as previously described.

The invention will now be more specifically described by reference to the following illustrative examples.

Example I and proteolytic enzymes, such as Rapidase 800, at a temperature of approximately 150 F., after which the fabric was scoured in rope form through hot water containing 4 pounds of soda ash per 100 gallons at a temperature of approximately 160 F., so as to remove the water soluble sizing from the goods, together with dirt, soil and other undesirable substances. From the scouring vessel, the fabric was transferred on reels to a bleaching kier into which was introduced a bleaching solution containing 75 pounds of 35% hydrogen peroxide and 150 pounds of sodium silicate per 1000 gallons of water. The bleaching liquor was heated to about 190 F. and then held at that temperature and circulated within the kier for about 5 hours. At the end of this time, the spent liquor was drawn off from the kier and the bleached goods were washed in rope form, water mangled and dried. The dry bleached fabric was then singed to remove the projecting cotton and polyester fibers in order to control pilling or balling up of the polyester fibers, and to improve the appearance of the goods. 7

The desized, bleached and singed fabric was next impregnated with a 5254 Twad. solution of sodium hydroxide at approximately room temperature and squeezed on a three-roll mercerizer pad, and then run through the tenter frame of a mercerizing range at a speed of about 50 yards per minute with the frame set from 3 to 6 under the grey width of the goods and with the washing system shut off so as to permit free shrinkage of the fabric in the filling direction. In this connection, it will be understood that the widthwise shrinkage of the fabric is produced both by the chemical action of the mercerizing solution and mechanically by reason of the fact that lengthwise tension is applied to the fabric, as by means of drag or tension bars and compensator rolls, continuously during passage of the goods through the mercerizing range as well as through the desizing pad box.

From the tenter frame, the goods were run through a series of open width Washers to remove the sodium hydroxide, passing twice through a seven-box washer fed with hot water at a temperature of approximately 180 F. and at a rate of 70- gallons per minute, and were then dried by passage through a drier of the steam heated revolving drum or can type, without any increase in width.

After drying, at which time the width of the goods had shrunk to 39%", the fabric was treated with resin in order to stabilize the recoverable stretch characteristics of the finished goods. To this end, the fabric was padded through a resin mix on a two-roll pad, the mix containing, per gallons of mix:

48 pounds of a triazone thermosetting resin, such as St-anset.

10 pounds of a buffered inorganic salt catalyst, such as the magnesium chloride Catalyst 100.

1 pound of a suitable wetting agent, such as the alky-laryl polyglycol ether Standapon 95.

1300 cc. of a dispersed blue vat pigment, such as GAPZ.

4500 cc. of an optical whitener fluorescent dye, such as Blancophor HS-31.

750 cc. of another fluorescent dye, such as Uvitex.

10 pounds of a self-emulsifying fatty-based ester derivative softener and lubricant, such as Cream 445.

After padding through the resin mix, the goodsiwere passed into a heated tenter frame set, in this instance, at a width of 43 inches, where they were dried. From the tenter frame, the dried fabric was passed through a curing oven at the rate of yards per minute, the temperature in the oven being about 340 F. and the curing time being approximately 72 seconds. The width of'the goods leaving the curing oven was 41 /2".

At this stage of the process, the fabric possessed the desired high width stretch and recovery properties. However, in order to remove any residual objectionable chemicals, such as unfixed resin, the goods were soaped, i.e., treated with a detergent, by passing them through four open width wash boxes containing an aqueous mixture of 2 pounds of 'alkylphenoxypoly ethanols per 600 gallons of water, heated to a temperature of approximately 180 F and then through three boxes of hot wash water of substantially the same temperature. After the soaping, the fabric was dried on steam heated drying cans, and then further treated by passage through a top softening mix on a two roll pad, the mix containing per 100 gallons of mix:

20 pounds of a self-emulsifying fatty-based ester derivative softener and lubricant, such as S-916.

40 pounds of another softener and lubricant, such as No. 735.

200 cc. of a vat pigment in dispersed form adapted to enhancethe shade of white, such as Violet.

Upon leaving the top softening pad, the goods were again dried on a tenter frame.

In all of the drying steps above mentioned other than thatfollowing the resin impregnation, it will be understood that the fabric was free from tension in the filling direction, although continuously under tension in the warp direction.

As the final step in the process, the fabric was shrunk on a compressive shrinking machine to provide a 1% residual shrinkage in length and the required shrinkage in width to produce a finished width of from 40 to 41".

Samples were then cut from the center section of the finished goods for laboratory testing as respects stretch ,and set, each sample being 3" x 9 with the 3f measurement slightly oversized so that, after unravelling the filling threads, the filling width was 3". Two clear lines or bench marks 3" apart were marked across the sample, and a clamp was placed on each end. The clamp'at one end was fastened to a bench while a 27 pound weight was attached to the clamp at the other end and suspended vertically fora period of minutes. At the end of the 10 minuteperiod, the increase in length of the 3" marked section was measured and calculated as the percent of stretch. After removing the weightand allowing the sample to recover" in a horizontal position for ten minutes, the increase in length of the 3" section was remeasured and calculated as the percent of set.

When the fabric "of the present example was tested in this manner, the following results were obtained:

Stretch Set Shrinkage I 4l Warp Filling Warp Filling Warp Filling ,Norn: Shrinkage indicates a gain.

It will also be understood that all of the test results herein set forth represent the average of several tests on samples taken from different rolls of the same finished lot, and are subject to normal variations within 1% or 2%.

Example II 'A'lot of 48%" wide 3.91 yards per pound 96 x 84 unbleached fabric made up of a blend of 50% cotton and 50% Kodel polyester fibers was desized, bleached, singed, mencerized, washedand dried in the same manner as that described in Example I, and a ain the width of the fabric after drying-had shrunk to' 39% I o After drying, the -fabric was padded through a bluing mix-on a two roll pad,-the mix containing per 100 gallons of'mix:

300 cc. of an optical whitener fluorescent dye, such as Blancophor HS-3-1. i 1

700 0c. of-another'fluorescentdye, such as Uvitex.

1 poundofa suitable wetting agent, such as the sodium alkylnaphthalene sulfonate- Nekal.

After padding through the bluingmix, the goods were dried on a heated tenter frame having a width setting of 43". From the tenter frame, the fried fabric was passed through a heat setting oven at the rate of 125 yards per minute, the goods being maintained under tension in the wanp direction but without tension in the filling direction, the temperature in the oven being approximately 385 F., and the heat settingtime being about 63 seconds. The width of the goods leaving the heat setting oven was 40%", indicating a decrease of approximately 2% duringthe' heat setting operation. This decrease in Width resulted from both-the mechanical tension on the warp in the absence of widthwise tension and the shrinkage effect of the heat on the polyester fibers in the filling. The heat setting process also imparted stability to the polyester fibers as respects shrinkage and wash-and-wear qualities.

Following the heat setting operation, the fabric was treated by padding on a two roll pad through a finishing mix containing, per gallons of mix:

40 pounds of another softener and lubricant, such as No. 735.

400 cc. of a vat pigment in dispersed form adapted to enhance the shade of white, such as Violet.

1 pound of a suitable wetting agent, such as the alkylaryl polyglycol ether Standapon 95.

cc. of an optical whitener flourescent dye, such as Blancophor HS-3l.

400 cc. of a blue vat pigment dispersion adapted to add a blue tint to the shade of white.

Upon leaving the finishing mix pad, the goods were again dried on a tenter frame so as to control the width of the finished goods.

As in the case of Example I, the last step of the process involved shrinking of the fabric on a compressive shrinking machine so as to control the residual shrinkage, primarily of the cotton content of the blend, and to provide a finished width of from 40" to 41".

When tested in the same manner as the fabric of Example I, the finished goods gave the following results:

Stretch Set Shrinkage Warp Filling Warp Filling Warp Filling NOTE! Shrinkage indicates a gain.

Example III A lot of 47" 3.47 128 x 82 35% cotton-65% Dacron fabric was processed by the same procedure as the cotton- Kodcl blend of Example II, except that the width of the fabric after the Washing and drying was 40%", and after the heat setting operation was 41". Testing in the manner previously described gave the following results:

Stretch Set Shrinkage Warp Filling Warp Filling Warp Filling :NOTEZ Shrinkage indicates a gain.

Example IV v A lot of 47" 2.30 1 05 x 52 35% cotton-65% Dacron fabric was also processed in the same manner as described in Example II, except that'the width of the fabric after washing and drying was 44", the fabric after padding through the bluing mix'was dried with the tenter frame set at 45 /2", and the width of the goods after the heat setting operation was 43 /2". When tested as described in Example I, the following results were obtained:

Stretch Set Shrinkage Warp Filling Warp Filling Warp Filling NOTE: Shrinkage indicates a gain.

It will be seen from the foregoing examples that the method of the present invention is capable of imparting high stretch and low permanent set characteristics in the filling direction to cotton-polyester blend fabrics of vari- 7 ous standard constructions, producing a stretch of from 15% to 30% of the finished width with a relatively high recovery.

While the starting fabric used in each of the examples was a standard greige construction woven from standard twist yarns, it will be obvious that the process is also applicable to reeded out and redesigned fabrics. In this connection, in order to provide a customer with a stretchable woven cotton-polyester fabric in substantially the same width, weight and thread count as the standard nonstretchabLe goods normally desired by that customer for the specific end use involved, it will usually be necessary to either reed out or redesign the greige construction so as to allow for the increase in warp thread count and density or weight per unit length which results from the abnormal shrinkage produced by the present process. Economically, this would enable the use of a lighter and somewhat cheaper per square yard greige cloth which would still provide a stretchable finished fabric sufiiciently heavy for its ultimate end use. Alternatively, a greige construction which is standard for one specific end use may be processed according to the invention so as to produce a stretchable fabric of standard specifications for a different end use.

Although specifically difierent procedures embodying the invention have been described in the foregoing examples, it should be clearly understood that these examples are illustrative only and do not define the limits of the invention, and that various changes in or additions to the procedural steps described, which will be apparent to those skilled in the art, may be made without departing from the inventive concept. For example, it will be obvious that cross linking and auxiliary agents other than those specifically mentioned may be used in the process for the purpose of stabilizing the filling stretch characteristics, softening, coloring and otherwise improving the properties of the finished fabric. It is equally obvious that the invention is applicable to woven cotton-polyester blend fabrics of widely varying weights and types, and that various degrees of stretch and recovery can be imparted to such fabrics to meet specifically different end use requirements. Furthermore, although the examples above described relate specifically to bleached fabrics, it will be understood that the process also applies to goods which are dyed to any desired color, preferably prior to the resin impregnating or heat setting phase of the procedure. Reference should therefore be had to the appended claims for a definition of the scope of the invention.

What is claimed is:

1. A process for treating fabrics Woven entirely from standard yarns consisting of a blend of cotton and polyester fibers to impart thereto high stretch and recovery properties in the filling direction only which comprises the following steps:

(a) desizing the fabric;

(b) shrinking the desized fabric in the filling direction by subjecting it to the action of a mercerizing agent While maintaining the fabric under tension in the warpwise direction and in .a substantially untensioned condition in the filling direction;

(c) washing the fabric while maintaining it under tension in the warpwise direction but without applying tension in the filling direction until substantially all of the mercerizing agent has been removed;

(d) drying the washed fabric without stretching in the filling direction;

(e) impregnating the dried fabric with a liquid mixture containing a fluorescent dye and a wetting agent;

(f) drying the impregnated fabric while restricting shrinkage thereof in the filling direction;

(g) heating the fabric to shrink and stabilize the polyester fibers of the filling yarns of the fabric while 8 maintaining the fabric under tension in the warpwise direction but without tension in the filling direction; and

(h) subjecting the fabric to a compressive shrinking operation to control the residual shrinkage of the cotton fibers of the fabric.

2. A process according to claim 1 including, between steps (g) and (h), the additional steps of:

(i) impregnating the fabric with a liquid mixture containing a softener and a white enhancing pigment; and

(j) drying the impregnated fabric while controlling the Width thereof- 3. A process for treating fabrics woven entirely from standard yarns consisting of a blend of cotton and polyester fibers to impart thereto high stretch and recovery properties in the filling direction only which comprises the following steps:

(a) wetting the fabric with an aqueous solution of sodium hydroxide of mercerizing strength;

(b) maintaining the wetted fabric under tension in the warpwise direction and in a substantially untensioned condition in the filling direction while the sodium hydroxide and the warpwise tension cause the fabric to shrink in width but not in length;

(0) washing thefabric to remove the sodium hydroxide while maintaining the fabric under tension in the warpwise direction but leaving the fabric slack in the filling direction;

((1) drying the washed fabric while applying tension in the warpwise direction 'but without increasing the width thereof; and

(e) heating the dried fabric at a sufficient temperature and for a'sufficient period of time to shrink and stabilize the polyester fi bers of the filling yarns of the fabric while maintaining the fabric under tension in the warpwise direction only.

4. A process as claimed in claim 3 including the additional step of:

(f) subjecting the fabric to a compressive shrinking operation to control the residual shrinkage of the cotton fibers of the fabric.

5. A process as claimed in claim 3 including, between steps ((1) and (e), the additional steps of:

(g) impregnating the dried fabric with a liquid mixture containing a softener and a white enhancing pigment; and

(h) drying the impregnated fabric while controlling the width thereof.

References Cited by the Examiner UNITED STATES PATENTS 2,404,837 7/1946 Goldthwait 139421 2,434,111 1/ 1948 Hawley et al. 28-74- X 2,477,652 8/ 1949 Robbins 161-92 2,491,396 12/1949 Seckel 161--92 2,774,129 12/1956 Secrist 8-125 3,075,274 1/ 1963 Mizell 28-74' 3,086,274 4/1963 Arnett 28-74 3,145,132 8/1964 Seltzer ..28--76 X 3,146,575 9/1964 Lund et al. 28--76 X.

' FOREIGN PATENTS 649,666 10/ 1962 Canada.

- OTHER REFERENCES Du Pont Textile Fibers Dacron Polyester Fiber E. I. v

du Pont de Nemours and Co. Bulletin D-SQ, June 1955.

MERVIN STEIN, Primary Examiner. Y

MACKEY,

DONALD W. PARKER, ROBERT R.

. Examiners.

Claims

1. A PROCESS FOR TREATING FABRICS WOVEN ENTIRELY FROM STANDARD YARNS CONSISTING OF A BLEND OF COTTON AND POLYESTERS FIBERS TO IMPART THERETO HIGH STRETCH AND RECOVERY PROPERTIES IN THE FILLING DIRECTION ONLY WHICH COMPRISES THE FOLLOWING STEPS: (A) DESIZING THE FABRIC; (B) SHRINKING THE DESIZED FABRIC IN THE FILLING DIRECTION BY SUBJECTING IT TO THE ACTION OF A MERCERIZING AGENT WHILE MAINTAINING THE FABRIC UNDER TENSION IN THE WRAPWISE DIRECTION AND IN A SUBSTANTIALLY UNTENSIONED CONDITION IN TH FILLING DIRECTION; (C) WASHING THE FABRIC WHILE MAINTAINING IT UNDER TENSION IN THE WARPWISE DIRECTION BUT WITHOUT APPLYING TENSION IN THE FILLING DIRECTION UNTIL SUBSTANTIALLY ALL OF THE MERCERIZING AGENT HAS BEEN REMOVED; (D) DRYING THE WASHED FABRIC WITHOUT STRETCHING IN THE FILLING DIRECTION; (E) IMPREGNATING THE DRIED FABRIC WITH A LIQUID MIXTURE CONTAINING A FLUORESCENT DYE AND A WETTING AGENT; (F) DRYING THE IMPREGNATED FABRIC WHILE RESTRICTING SHRINKAGE THEREOF IN THE FILLING DIRECTION;