US3883298A

US3883298A - Energy responsive thread

Info

Publication number: US3883298A
Application number: US305368A
Authority: US
Inventors: Gerald Platt
Original assignee: Individual
Current assignee: Individual
Priority date: 1969-10-13
Filing date: 1972-11-10
Publication date: 1975-05-13
Anticipated expiration: 1992-05-13

Abstract

An energy responsive thread which develops color upon activation by energy, especially electromagnetic energy, of a certain type or energy level. A preferred embodiment comprises a photosensitive thread which develops a permanent, specific color upon exposure to electromagnetic radiation of a specific wavelength. The photosensitive thread preferably contains photosensitive dyes which develop a permanent, specific color, upon exposure to electromagnetic radiation of a specific wavelength. Electromagnetic radiation falling within the ultraviolet, visible and infrared portions of the spectrum may be utilized. The thread may contain at least three dyes which individually develop red, blue, and green colors, The selective exposure of the individual colors provides all the colors of the visible spectrum.

Description

United States Patent 1 1 Platt I ENERGY RESPONSIVE THREAD [76] Inventor: Gerald Plait. 727 South 1 100 East.

Salt Lake City, Utah 84102 [22] Filed: Nov. 10. i972 [21] Appl. No.: 305,368

Related US. Application Data [63] Continuation of Ser. No. 865.917. Oct. 13. 1969.

abandoned.

[52] [1.8. CI. 8/2; 117/7; 8/79; 112/262; 96/90 R [51] Int. Cl D06p 5/00 [58] Field of Search l17/l.7; 8/2

[56] References Cited UNITED STATES PATENTS 2.206.611 7/1940 Lamtz 8/2 X 2.213.745 9/1940 Schinzell... 2.541.178 2/1951 Slifkin 3.016.308 1/1962 Macaulay 3.023.599 3/1962 Pellegrim 3.140.175 7/1964 Kaprelian 96/12 FOREIGN PATENTS OR APPLICATIONS 380.208 9/1932 United Kingdom 8/2 674.642 6/1952 United Kingdom 1 1 May 13, 1975 309.166 6/1930 United Kingdom 8/2 OTHER PUBLICATIONS Silk Journal and Rayon World, July 1945, pages 32 & 42.

Primary Examiner-Donald Levy Attorney, Agenl. 0r FirmTraslc & Britt [57] ABSTRACT An energy responsive thread which develops color upon activation by energy. especially electromagnetic energy, of a certain type or energy level. A preferred embodiment comprises a photosensitive thread which develops a permanent, specific color upon exposure to electromagnetic radiation of a specific wavelength. The photosensitive thread preferably contains photosensitive dyes which develop a permanent, specific color, upon exposure to electromagnetic radiation of a specific wavelength. Electromagnetic radiation falling within the ultraviolet. visible and infrared portions of the spectrum may be utilized. The thread may contain at least three dyes which individually develop red. blue. and green colors, The selective exposure of the individual colors provides all the colors of the visible spectrum.

7 Claims, 5 Drawing Figures am a? FIG.

COLORANT JF/G. 5 BY H i5 ATTORNEY ENERGY RESPONSIVE THREAD This is a continuation of application, Ser, No. 865,917 filed Oct. l3, I969, now abandoned.

BACKGROUND OF THE INVENTION In the manufacture of articles from textiles it is common commercial practice to sew various parts of fabric together to form a finished article. Clothing, draperies, tablecloths, furniture coverings and the like are frequently made of separate parts of fabric and joined at seams by threads sewn into the fabric. Frequently, the fabric has a color and often times a design of a multitude of colors. If fabric is a single color, a thread matching that color is preferably used to join the parts together If the fabric is a multi-colored article then a thread having a more or less neutral color is chosen. Nonetheless, the thread is very evident in multi-colored fabrics. It is an object of this invention to provide a thread which colonharmonizes with the surrounding fabric. It is an objective to provide a thread which is essentially colorless and which can be sewn into a multicolored fabric and which will develop permanent, specific colors which harmonize with the color of the fabric in the immediate vicinity of the thread.

INVENTION A novel energy responsive thread and method of sewing fabrics has now been invented. The thread contains energy responsive dyes which develop a specific, permanent color upon activation. The thread can be used to sew fabrics whereby the thread, upon activation before or after entering the fabric, develops a color to match the color of the fabric in the immediate vicinity of the thread. The thread upon proper activation, has the potential of developing all the colors of the visible spectrum.

The energy utilized to activate the novel thread of this invention may be thermal or electromagnetic. The use of electromagnetic energy, especially of a wavelength falling within the visible spectrum, is preferred in this invention. In describing novel threads which are responsive to electromagnetic radiation the term pho tosensitive" is frequently used.

A novel photosensitive thread has now been invented which develops a permanent, specific color upon exposure to electromagnetic radiation of the specific wavelength. The invention is especially useful inasmuch as multi-colored fabrics may now be sewn with a single thread and the color of the thread developed to match the color of the fabric in the immediate vicinity of the thread. Thus, the novel photosensitive thread of this invention has the ability to develop any or all of the colors of the visible spectrum.

Ordinary threads of cotton, nylon, saturated polyesters, cellulose acetate, rayon, and the like may be treated so that the resulting thread or filament is energy responsive and will develop a specific color in response to certain stimuli.

The invention can utilize energy responsive dyes, especially dyes which develop specific colors upon exposure to electromagnetic radiation of a specified wave length. In one embodiment of this invention the thread contains at least three dyes which individually can develop red, blue, and green colors. By selective development of the individual colors of each of these dyes all the colors of the visible spectrum may be obtained. The

dyes may be directly or indirectly attached to the threads and may be chemically or physically associated with the filament.

Further description of the instant invention may be facilitated by reference to the following drawings:

FIG. 1 is a cross sectional view of a filament having microspheres containing color-developable dyes attached;

Flg. 2 is an enlarged view of a cross section of a color-developable microsphere;

FIG, 3 shows an enlarged view of a twisted thread composed of three filaments each having a potentially different color;

FIG. 4 is a perspective view of a fabric being sewn with a photo-sensitive thread;

FIG, 5 is a perspective view of a fabric being sewn with a photo-sensitive thread.

FIG. 1 is a cross-sectional elevational view of a thread or filament 1 with a mono-layer of microspheres adhered thereto. These microspheres are very small, having a diameter on the order of about 0.01 inches to less than about 0.0005 inches. The microspheres contain chemical compounds which have a potential of becoming dyes or colorants. Microsphere 2 has the potential of becoming blue in color if properly activated. Microsphere 3 has a potential of becoming red in color while microsphere 4 has a potential of becoming green in color. Because these spheres are so small and packed together, it is possible to simulate any color found in the visible spectrum by selective activation of the individual colors. For example, if only the red and green spheres are activated the resulting confusion light emanating from the surface of the tightly packed spheres will cause the surface to appear yellow in color.

These spheres may be adhered to the filament by any appropriate binder. Starch type binders, for example, wheat flour, and the like, may be utilized in a water suspension to adhere the spheres to the filament. It is preferred, however, that the binder be water insoluble. Many resinous materials such as varnishes, shelacs and the like may be utilized as binders.

FIG. 2 illustrates an individual sphere. The interior portion 6 contains a chemical compound which is capable of becoming a dye or colorant under certain condi tions. The chemical compound may be disbursed in a gelatin or similar gelatinous material or may exist in liquid form encapsulated within an outer shell 5. Even if the center portion 6 is self-supporting, frequently an outer shell 5 is included and contains a light filter or other material which screens out undesired stimuli. In this manner the microsphere may be rendered activatable only by a specific type of stimuli. For example, a silver halide emulsion sensitized to be responsive to green light as well as blue light may contain a yellow filter to filter out the blue light, thus allowing the sphere to be sensitive only to green light. Since the screening layer may contain a dye which contributes color to the system, it is frequently preferred that the screening layer or shell 5 be water soluble and capable of easy re moval.

FIG. 3 is an enlarged view of a thread composed of twisted filaments, each filament having a different color. Since each filament is developable to one of the three basic colors, any color contained in the visible spectrum may be obtained by proper activation and de' velopment. These filaments may contain microspheres on the surface, such as the filament in FIG. I or the filaments may be saturated with the appropriate chemical compound and overcoated in the proper manner to protect against evaporation or undesired activation. The potential colorant or dye may, of course, be dispersed in a coating material such as gelatin and applied as a coating on the filament.

FlG. 4 is a prospective view of an apparatus which may be used with the photosensitive thread. Fabric passes under a sewing machine head 11 through which the photosensitive filament is threaded. The photosensitive thread is protected from light until it is threaded into the needle 12 and sewn into the fabric. A white light 13 is placed below the fabric and shines through the fabric thus exposing the thread 21 to the colors of the fabric in the immediate vicinity of the thread. After the thread is exposed it passes into a development zone 5 where the color is photodeveloped to match the color of the surrounding fabric. After developing the color of the thread, the fabric passes into a fixing zone 14 wherein the color of the thread is fixed, that is, rendered inactive to subsequent exposure to light. The developing of the thread may be either a wet or dry process depending upon the chemical characteristics of the photosensitive filament. The same is true of the fixing process.

FIG. 5 is a schematic representation of another apparatus and method for sewing fabric with a photosensitive thread 21 to match the colors of the fabric. A light and color meter 16 reads the intensity and color of the fabric at a pre-determined point. This information is conveyed to a control mechanism 17 which directs the color and intensity of light emanating from the lamp 18. The lamp l8 exposes thread 21 at a predetermined point to the same colors and intensity oflight read from the fabric by meter 16. A portion of the fabric and the portion of the thread exposed are in a fixed relationship so that the exposed thread will enter that portion of the fabric which the thread matches in color. After the thread 21 is exposed it proceeds into a developing chamber 19 and then into a fixing chamber 20. In this apparatus the color of the thread is developed and fixed to match a particular portion of the fabric before it is sewn by a machine needle 12 into the fabric.

in its broad aspects, this invention embodies an energy-responsive thread which develops a permanent specific color. Such a thread is especially useful for sewing together colored fabrics wherein the color ofthe thread is developed to match that of the fabric. The thread in its undeveloped state preferably has a potential of being developed to match any color of the visible spectrum. The thread may be exposed and color-developed prior to the time it enters the fabric or the thread may be exposed and developed after it enters the fabric.

Photosensitive threads are one type of energyresponsive threads which are especially useful inasmuch as a minimum of translation is necessary between the color sensing device and the exposure device. FIG. 4, above, illustrates a device wherein the photosensitive thread is exposed to light possessing the wavelength of the color which the thread is to match. There is no translation of different types of energy in this system. The thread is subsequently developed and the color fixed.

A photosensitive thread of the type illustrated in FIG. 1 may be fabricated by adhering minute, discrete, spheres, which are capable of developing the three basic colors; blue, green, and red or their counterparts,

yellow, cyan, and magenta. These spheres can contain dyes which develop a permanent, specific color upon activation. A direct way of activating the dye comprise, using light of the wavelength of the color desired. The dyes utilized may be photosensitive or may be oxidizable to yield the desired color. oxidizable dyes may be used in conjunction with silver halide wherein the oxidizing condition is created during the reduction of the silver halide to metallic silver by the action of light.

Silver halide emulsion for photographic films are well known. Silver halide systems, however, are sensitive only to blue light (4005OO millimicrons). To render silver halide system sensitive to green light (500-600 millimicrons) and red light (60()-700 millimicrons) it is necessary to use a sensitizing agent. The preparation of photographic grade emulsions containing silver halides, for example, silver bromide, and the sensitization of said emulsions to render them sensitive to green and red light is well known in the photographic art. Three separate emulsions may be prepared, one sensitive only to blue light, another sensitive only to green light, and a third sensitive only to red light. Since silver halides are naturally sensitive to ultra-violet and blue light, emulsions sensitive only to green or red light must be protected from the blue and ultra-violet radiation. This can be accomplished by utilizing a light filter which filters the blue and ultra-violet. To each of the emulsions is added a precursor of a dye of the color to which that emulsion is sensitive. For example, to the emulsion sensitive to blue light is added a pre-cursor which forms a blue dye in combination with the developer in the presence of activated silver halide. Thus, if the blue sensitized emulsion has been exposed to light containing electromagnetic radiation in the blue region of the spectrum, the silver halide present will be activated and upon development will be reduced to metallic silver. The dye pre-cursor and developer form a blue dye under the oxidizing conditions present.

Microspheres of the gelatin photographic emulsion may be formed in diameters of about 0.005 inches or less to a diameter of about 0.01 inches. Microspheres of blue, green, and red sensitized photographic emulsions developable to the color of sensitization could be randomly adhered to a thread or filament. One method of adhering microspheres to filaments comprises passing a tacky filament through an agitated or a fluidized bed of a mixture of the microspheres. The resulting thread with microspheres attached would have the appearance shown in enlarged form in FIG. 1 although the spheres would not necessarily be limited to a single layer. The thread would then be packaged in a lightprotected enclosure and utilized in a sewing machine in the manner shown in FIGS. 4 or 5. The thread could be developed to its proper color either before or after it is sewn into the fabric.

Upon exposure to light silver halide becomes activated. For example, if the light to which the filament is exposed contains only green light then the spheres sensitive to green light will be the only ones in which the silver halide is activated. The activated silver halide, e.g., silver bromide, can then be reduced to metallic silver upon contact with developer solution. The solution can also interact with the dye precursor to form a dye in those spheres in which the silver halide has been activated. For example, if the spheres sensitive to green light are the only ones in which silver halide has been activated, then the interaction of developer with the pre-cursor or coupler, as it is frequently called, results in a green dye. For example, if the green sensitized microsphere contains pentochloro-alpha-nuphthor as the coupler and is contacted with ethyl-paraphenylene diamine as the developer, a green dye will be formed if activated silver halide is present and reduced to metallic silver by the developer.

After development, the thread and fabric to which it is sewn are treated with a fixing solution so that subsequent exposure to light will not activate any of the silver halide present. In this manner the desired color obtained during the controlled exposure will be the only color developed by the photosensitive thread. During fixation it is generally desired to rinse the thread and the material first preferably with a water solution containing a mild acid such as acetic acid, diglycolic acid or the like, to neutralize any developer present. The photographic material can then be treated with a fixing agent such as a thiasulfate to react with the silver halide present to obtain a stable silver compound. A developing and fixing stage may be accomplished in one step utilizing known techniques.

Photosensitive threads may be constructed without the use of a silver halide. U.S. Pat. No. 3,445,234 discloses image forming compositions which form colored dyes in response to activation by ultra-violet light. A solution of bis-(4-diethyl amino-o-toluyl-methane-trihydrochloride with an equal weight of 2,2'-bix(ochlorophenyl)-4,4', 5,5'-tetraphenylbiimidazole in equal parts by volume of benzene in NN-diethyl formamide could be utilized to impregnate a microsphere of gelatin or other carrier. When exposed to ultraviolet light a blue coloring appears. Thus, if such a microsphere were sensitive only to a certain wavelength of ultraviolet light, the microsphere could be activated in a system such as that shown in FIG. 5 wherein the color of the fabric is read and the information communicated to an energy source. If blue is one of the colors appearing in the fabric then the energy source or exposure light would be controlled to emit the wave-length of ultraviolet light which would activate the sphere having the potential of developing a blue color.

Compositions are disclosed in U.S. Pat. No. 3,445,234 which develop a green color upon exposure to ultraviolet light and which develop a red color upon exposure to ultraviolet light. By using the proper screening agents a microsphere having the potential of developing a red color could be rendered sensitive only to ultraviolet light in the range of 300 to 400 millimicrons. Similarly, a system having the potential of developing a green color could be sensitive only to wavelengths of 200 to 300 millimicrons while a blue system could be rendered activatable only by ultraviolet lights of 100 to 200 millimicrons. Thus, by using the systems in conjunction with a system disclosed in FIG. 5 a red color can be obtained where a red color is detected in the fabric.

Once the desired color is achieved through exposure and development, the color may be fixed by the addition of hydroquinone or other deactivator to the systern.

A similar non-silver system can be obtained using the compounds disclosed in U.S. Pat. No. 3,445,232 wherein microspheres may be obtained in the manner disclosed above.

EXAMPLE 1 Three separate batches of gelatin spheres impregnated with photosensitive silver chloride emulsions are prepared. A sensitizing agent responsive to green light (500-600 mu) is included in one emulsion while another emulsion is sensitized in the 600-700 mu (red) region. The remaining emulsion contains no sensitizer and is, therefore, sensitive only to blue light (400-500 mu). Silver chloride emulsions are sensitive only to UV light and blue light unless separately sensitized.

A photographic grade emulsion is prepared by suspending silver chloride or, preferably, silver bromide, in a solution of gelatin.

An alternative method of preparing a photographic grade emulsion comprises the addition of an alcoholic metal halide, such as potassium bromide, to gelatin containing silver nitrate. 1f this method is used, it is preferred to wash the alkali metal nitrate from the gelled colloid. Microspheres of the gelatin are formed as the emulsion is cooled. Typically, the sphere is about 10% to 50% by weight of silver halide, although preferably the silver halide concentration is about 20% to 40%. The concentration used in this example is about 25%. The microspheres may be formed by slowly feeding warm silver halide containing gelatin into one end of a small, hollow rotating tube and cooling the gelatin as it passes the length of the tube.

The microspheres are conventionally less than about 0.01 inches in diameter although best results are achieved when the sphere diameter is less than about 0.005 inches and preferably less than about 0.001 inches. Spheres of 0.0005 inches and less are especially useful in conjunction with fine filaments.

The microspheres may be formed by atomization, prilling and similar techniques.

Other protective colloids which may be substituted for gelatin include agar agar, albumen, caesin, collodion, cellulose esters and the like.

Microspheres sensitive to red light (600-700 mu) are prepared by including a blue dye in the formulation. This may be accomplished by adding the dye to the photographic-type emulsion or by absorption of the dye by the microspheres. The dye is included as about 0.1 to 10.0% by weight of the weight of the total system. Dyes which sensitize silver halides to red light include pinacyanol or L1 '-diethy1-2,2'carbocyanine chloride, dicyanine or l,l'-diethyl-2,4'-carbocyanine chloride, 3,3'-diethyl-4,5,4'5'-dibenzothiacarbocyanine bromide, 3,3'-dimethyl-9-phenyl-4,5,4'5'-dibenzothiacarbocyanine chloride, 3-ethyl-5- 4-(3-ethy1-2- benzothiazolinylidine)-2-butenylidene rhodanine, 3- ethyl-5-4-( 3-methyl-2-benzothiazolinylidine)-l ,3- neopentylene-Z- butenylidene rhodanine and the like. Other dyes known to sensitize silver halides in the red region of the visible spectrum may also be utilized. These dyes are included, preferably, in concentrations which do not substantially contribute any color to the sphere.

To the spheres sensitized to light wavelengths of 600-700 mu, a coupling agent is added which reacts with developer under oxidizing conditions to form a red dye. Sufficient quantity of the coupling agent should be added so that substantial color is contributed if a substantial quantity of silver halide is activated by light of 600-700 mu. The activation of silver halide and its subsequent reduction of metallic silver provides oxidizing conditions.

Suitable couplers and developers to obtain red dyes include:

coupler developer phenyl-cyammethylacetone N-phenylhomophlhalimide The quantity of coupler included in the emulsion can be as great as the system will tolerate. The minimum quantity should be the least quantity which will contribute color upon activation and development of silver halide. Ordinarily. the coupler should be included as approximately 10% to about 100% of the molar concentration of the silver halide. In this example the coupler molar concentration is 50% of the silver chloride concentration.

Microspheres sensitive to green light (500-600 mu) are prepared by including a dye such as corallin, erythrosin, l,l '-diethyl-2,4'-cyanine iodide (ethyl red), ],ldiethyl-6,6-dimethyl-2,4'-cyanine bromide (orthochrome T). l,] -diethyl-6,6'-diethoxy-2,4-cyanine bromide (pinadirome), and l,] '-diethyl-2,2'-cyanine iodide. Other dyes known to sensitize silver halides in the green region of the visible spectrum may also be utilized. The dye is added at about 0.1% to about 10% by weight of the total system. The sensitizing dye is preferably added in concentrations which do not sub stantially contribute any color to the sphere.

To the spheres sensitized to light wavelengths of 500-600 mu, a coupling agent is added which reacts with developer under oxidizing conditions to form a green dye. Sufficient quantity of the coupling agent should be added so that substantial color is contributed if a substantial quantity of silver halide is activated by light of 500-600 mu.

Suitable couplers and developers to obtain green dyes include:

coupler developer pentachloro-a-naphthol diethyl-p-phenylene diamine pyrimidazolone 4amino-3-methylN .N-diethylamiline The quantity of coupler included in the green light sensitized spheres is within the same range of concentrations set forth for the red light sensitized spheres.

The red and green sensitized microspheres are coated with a thin layer of gelatin containing a yellow dye to prevent blue light from passing into these spheres. The yellow dye is water soluble and easily removable from the surface of the microspheres.

Microspheres sensitive to blue light (400-500 mu) are prepared without addition of sensitizers inasmuch as silver halides are naturally sensitive to blue and ultraviolet light. A coupling agent is added which forms a blue dye upon reaction with developer under oxidiz ing conditions. It is added to the microspheres sensitive only to blue light.

Suitable couplers and developing agents include:

coupler developer a-naphthol diethyl-p-phenylene diaminc C H COCH,CONH C H 4-amino-3-methyl-N.Ndiethylaniline The quantity of coupler included in the spheres sensitive to blue light is within the range of concentrations set forth for the red light sensitized spheres.

Equal quantities of spheres sensitive to red, green, and blue light are placed in a container having a light weight cotton thread passing upwards through an orifice at the bottom. The thread is coated with a wet starch binder. Other binders, of course, could be used. Resinous binders such as lacquers, varnishes, etc. are preferably utilized when water resistance is desired.

The spheres are randomly placed in the container. Mile agitation or mild fluidization can be utilized to maintain the microspheres in a loose, random orientation.

As the sticky thread passes upwards through the container, microspheres adhere thereto in a random fashion. The microspheres form essentially a monolayer on the surface of the thread.

The thread is allowed to dry before use.

The above operations are conducted in the absence of visible or UV light so that the silver halide is not acti vated.

The dried thread is wound into an enclosed container where it continues to be sealed from light.

The thread is then placed in an apparatus of the type set forth in FIG. 4 where it is sewn into a multi-colored fabric with a light source sufficient to expose the thread located below the fabric. After exposure the thread and fabric is developed by treatment with a developer as set forth above. The time required for development may vary from a few seconds to several minutes. The speed of development increases with increased temperature. Temperatures above room temperature are preferred in hastening development. Temperatures of about l00 F. to 200 F. may be used to maintain a development time of less than 1 minute.

After development the color is fixed by immersion or washing with a typical sodium thiosulfate solution used in the photographic industry. A small quantity of an organic acid is preferably included in the aqueous fixing solution in accord with known practices in the photographic industry. The time of fixing may be accelerated by increased temperatures, for example, above 60 F the fixing time may be reduced substantially below 1 minute.

The thread which has been so treated matches in color the fabric into which it had been sewn.

Although the above example sets forth the preferred mode of practicing this invention, the invention is not limited to silver systems or the methods described therein.

As set forth above, non-silver photographic systems known to the art may be utilized. These systems are susceptible of being activatable by specific stimuli, for example, specific wavelengths of electromagnetic radiation, to develop a certain desired color. Known light filters may be utilized to exclude unwanted wavelengths of light from an activatable system.

Although the coating of a filament with microspheres containing activatable systems is a presently preferred construction, numerous other structures may be utilized. The dyes or activatable compounds may be ap plied in layers to a filament in a manner similar to that used in constructing color film in the photographic art. Also, as shown in H0. 3, three filaments may be interwound in a fashion wherein each develops a primary color. in this embodiment the filaments may be saturated with the dye and overcoated with gelatin or comparable coating material.

The invention utilizes the techniques of color photography wherein any color of the spectrum is created by proper development of the primary colors, red, green, or blue. Other basic color systems would be used, for example, where cyan, magenta or yellow, are the three colors, similar to the substractive color method of color photography. The positive primary colors, green, red and blue, are preferred for use in this invention.

The light filters suggested above for screening-out unwanted colors are well known in the photographic film art. These known light filters for photographic films may be utilized in this invention.

The resinous binders useful for adhering microspheres to threads in this invention are preferably colorless as well as water insoluble. Known binders and adhesives may be utilized for this purpose.

The state of the art in color photography is represented by the following texts: C. E. K. Mees and T. H. James, The Theory of the Photographic Process, The Macmillan Co., (i966) and Neblette, Photography, Its Principles and Practice, 4th edition Van Nostrand Co.

Although the invention has been described above with reference to specific embodiments, it is not intended that the invention be limited solely thereto but to include all the modifications and variations falling within the scope of the appended claims.

I claim:

1. A method of sewing a colored fabric comprising a. stitching said fabric with a thread having three light sensitive dyes which develop a specific, permanent color upon exposure to light, and

b. exposing said thread to light to develop a color matching that of the fabric in the immediate vicinity of said thread.

2. The method of claim 1 wherein said light sensitive dyes develop colors of red, green and blue upon exposure to light of the visible spectrum.

3. The method of claim 1 wherein at least one of said dyes is protected by a light filter.

4. The method of claim 1 wherein a silver halide is present with said dyes.

5. The method of claim 1 wherein said dyes are separately contained in microspheres adhered to said thread.

6. The method of claim 2 wherein said thread after exposure is treated with a developer.

7. The method of claim 6 wherein said developed thread is treated with a fixing solution.

Il t i

Claims

1. A METHOD OF SEWING A COLORED FABRIC COMPRISING A. STITCHING SAID FABRIC WITH A THREAD HAVING THREE LIGHT SENSITIVE DYES WHICH DEVELOP A SPECIFIC, PERMANENT COLOR UPON EXPOSURE TO LIGHT, AND B. EXPOSING SAID THREAD TO LIGHT TO DEVELOP A COLOR MATCHING THAT OF THE FABRIC IN THE IMMEDIATE VICINITY OF SAID THREAD.

4. The method of claim 1 wherein a silver halide is present with said dyes.