US3351419A

US3351419A - Permonosulfuric acid-hydrogen peroxide wool shrinkproofing combined with dyeing

Info

Publication number: US3351419A
Application number: US346070A
Authority: US
Inventors: Fell Eric Tom; Fox Scott Arthur
Original assignee: Prec Processes Textiles Ltd
Current assignee: Precision Processes Textiles Ltd
Priority date: 1963-02-25
Filing date: 1964-02-20
Publication date: 1967-11-07
Anticipated expiration: 1984-11-07
Also published as: CH219464A4; BE644323A; AT263686B; NL6401752A; FR1383457A; CH420047A; GB1071053A

Description

3,351,419 PERMONOSULFURIC ACID-HYDROGEN PER- UXIDE WOOL SHRINKPROOFING COMBINED WlTH DYEENG Eric Torn Fell, Amber-gate, and Scott Arthur Fox, Heage, England, assignors to Precision Processes (Textiles) Limited, London, England, a British company N Drawing. Filed Feb. 20, 1964, Ser. No. 346,07 0 Claims priority, application Great Britain, Feb. 25, 1963, 7,426/ 63 14 Claims. ((Ii. 817) This invention relates to the treatment of animal hair and materials consisting of or containing animal hair, more especially wool, in such forms as loose fibres, carded sliver, combed tops, yarns and woven and knitted fabrics.

An object of the invention is to provide an improved process for the treatment of animal hair and materials consisting of or containing animal hair to reduce the felting tendency thereof.

Several processes have been devised for reducing the tendency of wool to felt. Among the most successful of such processes is that described in British specification No. 716,806 according to which the tendency of wool to felt or shrink is minimised by treating goods consisting wholly or partly of wool with an aqueous solution of permonosulffuric acid or a salt or salts thereof, the said solution being adjusted to a pH value less than 8 when necessary, and then treating the goods with an aqueous solution or dispersion of a salt or salts of sulphurous acid or with a compound which produces such a salt or salts in aqueous solution. Goods thus treated may still require a bleaching treatment prior to dyeing especially if the goods are to be dyed a pale shade. Among the bleaching agents which may be employed is hydrogen peroxide.

It has now been found that if, in the above process, instead of using sulphurous acid or a salt or salts thereof in the second stage, there is used an aqueous solution of hydrogen peroxide or of a substance which under the con ditions employed acts as a source of hydrogen peroxide, the tendency of wool and other animal hairs to felt or shrink is also minimised and the goods produced have a better colour than those produced by the already known process. No separate bleaching operation is necessary and the treated goods are ready for dyeing. The treatment with sulphurous acid or a salt of sulphurous acid may thus be omitted without diminishing the resistance of the treated goods to felting.

Accordingly, the present invention provides a process for reducing the tendency of animal hair and materials consisting of or containing normal animal hair to felt which comprises applying thereto an aqueous solution of permonosulphuric acid or a salt or a salt thereof having a pH value of less than 8 in aqueous solution and as the next essential step, treating the product with an aqueous solution of hydrogen peroxide.

The treatment with permonosulphuric acid or a salt thereof may be carried out at any tempeature ranging from about room temperature to 100 C., but is preferably carried out at a temperature not exceeding 70 C. Preferably permonosulphuric acid and its salts are used in dilute aqueous solution. The concentration of the solution and the conditions of application should avoid substantial degradation of the wool.

After treatment with permonosulphuric acid or a salt thereof the goods may, if desired, be washed with water or with water containing an alkali prior to treatment with the hydrogen peroxide solution. Although such treatment is preferred it is not essential and any necessary chemicals for adjusting the pH value to the desired value may be already present in the hydrogen peroxide solution or may be introduced thereinto during the early stages of ice the treatment. Under the preferred conditions of operation the treated goods are, when introduced, acid in reaction and will at least tend to acidify the hydrogen peroxide bath unless steps are taken to check this by the introduction of an acid acceptor such as an alkali metal carbonate or bicarbonate or the use of an alkali metal phosphate or similar butter.

The aqueous hydrogen peroxide solution is preferably a dilute solution and may, for example, be a 0.5 to 10 volume solution. Stronger solutions, for example, a 15 volume solution, may, however, be used especially when it is desired to carry out the treatment as rapidly as possible. The hydrogen peroxide may have been generated in situ from an oxide or peroxide which in aqueous or aqueous acid solution gives rise to hydrogen peroxide provided that the ions concomitantly introduced into the solution are colourless or, if coloured, are readily washed from the treated goods or readily converted into stable colourless ions. Thus, a solution of hydrogen peroxide suitable for use in the process may be produced by dissolving an alkali metal peroxide such as sodium peroxide in a dilute aqueous mineral acid. The most suitable temperatures for the hydrogen peroxide treatment are room temperature to about 60 C. The solutions employed are preferably neutral or mildly alkaline solutions: thus solutions having pH values in the range 6.5 to 10.5 may be used, the preferred pH values being 8.0 to 9.0.

Suitable adjuvants such as surface active agents which assist in securing uniform penetration and wetting of the goods are preferably present in the bath containing permonosulphuric acid or a salt thereof.

After the treatment with aqueous hydrogen peroxide solution the goods are preferably rinsed to remove any excess hydrogen peroxide therefrom.

It is surprising that treatment with a further oxidising agent following the treatment with permonosulphuric acid and its salts should give results which are usually better than those that have hitherto been obtained with sulphites and/or bisulphites which are reducing agents. In the case of goods which are to be white when finished or are to be dyed a pale shade, the present invention enables the use of a separate bleaching step following treatment to impart shrink resistance to be eliminated with consequent economies in cost of materials.

According to a feature of the invention, wool and other kinds of animal hair which have first been treated with a solution of permonosulphuric acid or a salt or salts thereof and then with an aqueous solution of hydrogen peroxide acquire a reactivity towards reactive dyestuffs which the untreated materials do not possess. This reactivity is of an exceptionally uniform character and the thus treated materials when subsequently treated with reactive dyestuffs under alkaline conditions give exceptionally uniform dyeings and printings. The results thus obtainable are much more uniform than those obtainable when chlorinated wool has been dyed with reactive dyestuffs: the latter dyeings are skittery. The dyestuffs can be applied at or somewhat above room temperature. Only a short treatment is necessary. The coloration is thus applied under conditions which do not exert any harmful effect upon the pretreated wool or hair. Thus shrink resistance may first be imparted to the wool or hair and the dyeing or printing then carried out as a sequential operation. It appears that the successive treatment with permonosulphuric acid or a salt thereof and then with hydrogen peroxide modifies the chemical structure of the wool or other animal hair in such a way that a substantially uniform distribution of readily reactive hydrogen atoms is introduced thereinto; these hydrogen atoms are then available for reaction with the reactive dyestuffs. The treatments must, however, be given in the order set forth in order to secure both shrink resistance and ready coloration with reactive dyestuffs.

The process of the invention may be used for imparting shrink resistance and then dyeing or printing piece goods comprising or consisting of wool or other normal animal hairs, for example, cashmere goods. The process of the invention may also be used for the coloration of human hair whether on the human head or otherwise.

The dyestutf and acid acceptor may be applied to wool and other kinds of animal hair by immersion in a dyebath containing the dyestuif and acid acceptor in solution, which dyebath may also contain any conventional textile auxiliaries such as wetting and levelling agents suitable for use with reactive dyestuffs. The dyestuff and acid acceptor may also be applied by a padding technique or may be applied to selected areas only of the hair fibrecontaining textile material by a printing technique. For such applications the printing compositions may include thickeners which are substantially inert towards the reactive dyestuffs.

The reactive dyestuffs which may be used. are those which contain at least one water-solubilising group in the dyestutf molecule as well as a group which is capable of forming a covalent link by interaction with an active site in the wool molecule or of forming in situ a group which will react in this way. The active sites in the wool molecule which have been subject to treatment in the manner described are accepted as being amino, hydroxyl and sulphydryl groups: these groups are not readily available for reaction in untreated wool. Whatever the nature of the groups introduced into or made available by the treatment it has been experimentally established that they behave in a manner analogous to amino, hydroxyl and sulphydryl groups.

The water-solubilising group present in the dyestutf molecule may be a carboxylic acid or sulphonic acid group or a salt of such group with an alkali metal, animonia or an amine. One or more such groups may be present in the dyestuif molecule.

The group which is capable of forming a covalent link may be a group containing a reactive halogen atom such as that present in a monoor di-chloro-sym-triazinyl, a trichloropyrimidyl, a beta-halogenpropionyl, a beta-halogenoethylsulphonyl, a beta-halogenoethylsulphamyl, a chloroacetylamino or a beta-(chloromethyl)-beta-sulphatoethylsulphamyl group; a reactive sulphate group such as that present in a -beta-sulphatoethylsulphonyl group; a reactive hydroxyl or esterified hydroxyl group such as that present in a beta-hydroxyethylsulphonyl, a beta-alkylsulphonyloxyalkylsulphonyl, a beta-arylsulphonyloxyalkylsulphonyl or a beta-acyloxyalkylsulphonyl group: an ethylenically unsaturated group such as an acryloxyamino or vinylsulphonyl group; an alkyl phosphite group or a sulphonfluoride group. In the case of the sym-triazinyl and pyrimidyl groups in place of a reactive halogen atom or atoms there may be present other substituents which are dissociable in the presence of alkalies such as sulphonic acid; thiocyanate; negatively substituted aryloxy and arylthio groups such as sulphophenoxy, sulphophenylthio, nitrosulphophenoxy, disulphophenoxy and sulphonaphthoxy groups; quaternary ammonium groups; heterocyclic and fused heterocyclic thiol groups having five or six atoms in the heterocyclic ring which are linked through a carbon atom of the heterocyclic to the thiol group; dithiocarbamic acid groups having the general formula in which R and R are like or unlike and each is an alkyl, cycloalkyl, aryl or aralkyl group or R and R taken together with the nitrogen atom form a heterocyclic ring having five or six atoms in the ring; or a group having the general formula in which R and R are like or unlike and each is a hydrogen atom or an alkyl, aryl or aralkyl group.

The dyestuffs used may belong to such classes as the nitro, azo, anthraquinone or phthalocyanine series and may be free from metal or contain metal complexed therein. An account of the commercially available kinds of reactive dyestuffs will be found in the Journal of the Institut Textile de France, September 1960, at pages 43 et seq.

In carrying out the coloration process of the invention the wool or other hair-containing goods has applied thereto a solution of or a paste comprising a water-soluble reactive dyestulf and a substance which acts as an acid acceptor. Any water-soluble reactive dyestuff which may be used to produce dyeings of high wet fastness upon cellulosic materials in the presence of an acid acceptor may be used in the process of the present invention.

The acid acceptor employed may be any of those which may be used as alkaline substances in the coloration of cellulosic materials with water-soluble reactive dyestuffs. These include soda ash, sodium and potassium carbonates, bicarbonates and silicates and trisodium and tripotassium phosphates.

With respect to the amount of acid acceptor present this should be at least sufficient to combine with any acid liberated by the reaction or reactions which lead to dyestufi fixation. As a general rule amounts up to 3% of the weight of the aqueous dyebath are employed with corresponding proportions in the printing pastes.

In addition there may be added to the dyebaths and printing pastes levelling agents and organic solvents in which the dyestuffs are readily soluble and which assist the uptake but with which the dyestuffs do not preferentially react under the conditions of use, and which are at least moderately soluble in water.

Some of the reactive dyestuffs will react with wool at substantially room temperatures: these are those containing a dihalo-sym-triazinyl group or a beta-sulphatoethylsulphonyl group. The remainder, including those containing monohalo sym triazinyl and trichloro pyrirnidyl groups, are preferably applied at temperatures higher than room temperature but not exceeding 60 C. These dyestuffs containing a dichloro-sym-triazinyl group have been found to require a much shorter period for fixation with chemically modified wool than any other available type. In the case of dyeings with those dyestuffs which require temperatures substantially above room temperature for fixation it has been found that the addition of watersoluble electrolytes such as sodium chloride and sodium sulphate will assist fixation.

The present invention enables level dyeings to be obtained in a cold dyeing process (2030 C.) in a short time: these dyeings are much more level than those obtained when a reactive dyestutf is applied to chlorinated wool. Due no doubt to the bleaching action of the hydrogen peroxide bright fast pastel shades may be readily obtained: such shades are almost unobtainable on chlorinated wool. Dyeings and prints obtained by this process are of excellent fastness to washing.

The following examples illustrate the nature of the invention:

Example 1 parts by weight of wool was treated in a hath made up from 3000 parts of water and 2 parts of permonosulphuric acid at 25 C. for 30 minutes. The thus treated wool was then entered into a fresh bath of 3-volume aqueous hydrogen peroxide solution, the pH value of which had been adjusted to 8.5 with sodium pyrophosphate. The wool was held in this bath for one hour at 50 C., rinsed and dried. This wool had good resistance to shrinkage when washed in aqueous washing liquors.

Example 2 Samples of wool serge were treated as follows:

All the samples (each 100 parts by weight) were treated in a bath made up from 3000 parts of water and 2 parts of permonosulphuric acid at 25 C. for 45 minutes. The samples were then given the following treatments:

(a) Rinsed and then treated with an aqueous solution containing 2 gm. per litre of sodium pyrophosphate at 50 C. for 30 minutes.

(b) Rinsed and then treated for 30 minutes at 25 C. in a bath made from 3000 parts of water and 20 parts of sodium sulphite crystals.

(c) Rinsed and then treated for 4 hours at 50 C. in a 3-volume hydrogen peroxide solution having pH of 7.

The thus treated samples and a control were then submited to a 50 minute washing test in a washing machine and the diminutions in width and length, due to shrinkage, determined. The results were as follows:

Dlmlnutions in percent Treatment Width Length Area Untreated control 15. 7 20. 4 32. 9 Permonosulphun'c acid-l-(a) 8. 4 12.6 19. 9 Permonosulphuric acid+(b) 2. 6 6.3 8. 74 Permonosulphurie aeid+(c) 1. 0 5. 1 6. 04.

Samples of flannel were treated as follows:

All the samples were treated in a bath of permonosulphuric acid similar to that used in Example 2. The samples were then given the following treatments:

(2.) Rinsed only;

(b) Rinsed and then treated for 30 minutes at 25 C. in a bath made from 3000 parts of water and 20 parts of sodium sulphite crystals;

(c) Rinsed and then immersed in 3-volume hydrogen peroxide solution at pH 8.5 for 3 hours at 50 C.

The thus treated samples and a control were then submitted to the same washing test as that employed in Example 2 with the following results:

Diminutions in percent Treatment Width Length Area Untreated control 23. 6 12. 6 33. 2 Permonosulphuric acid-l- (a) 12. 6 7. 7 19. 33 Pernionosulphurie acid+ (b) 0. 9 1. 4 2. 38 Permonosulphuric acid+ (c) -6. 4 -2. 9 9. 48

peroxide were whiter in colour than those given a second treatment with sodium sulphite and had a softer handle. Other tests have confirmed that woolen goods of various types, including cashmere goods, are of whiter colour and have a softer handle when the treatment which follows the permonosulphuric acid treatment is given with hydrogen peroxide, especially mildly alkaline hydrogen peroxide, instead of with a salt of sulphurous acid.

Example 4 Thirty parts by weight of a woolen fabric was treated in a bath of permonosulphuric acid similar to that used in Example 2. The fabric was rinsed and then immersed in 3-volume aqueous hydrogen peroxide solution at pH 8.5 for 3 hours at 50 C. The thus treated fabric was then dyed in the following dyebath:

Parts by wt. Water 1000 Soda ash 10 Procion Red G 2 Dyeing was carried out in this bath for 10 minutes at 25 C. and the fabric was then well rinsed. A level dyeing of good fastness was thus obtained. No steam or other heat treatment was needed to secure fixation of the dyestuif.

Example 5 Thirty parts by weight of flannel was subjected to the treatments with permonosulphuric acid and hydrogen peroxide described in Example 4 except that the duration of the hydrogen peroxide treatment was 15 hours. The thus treated fabric was then dyed in the following dyebath:

Parts by wt. Water 1000 Trisodium phosphate 20 Procion Orange Brown HGS 2 Exiample 6 Several pieces totalling in weight parts of wool flannel were immersed in a bath made up from 3,000 parts of water, 2.5 parts of permonosulphuric acid, 2 parts of a nonionic wetting agent sold as Tergitol TMN for 45 minutes at 25 C. The treated wool was then entered into a fresh bath consisting of 3,000 parts of 3- volume aqueous hydrogen peroxide solution the pH value of which had been adjusted to 8.5 with sodium pyrophosphate. The pieces were held in this bath for 4 hours at 50 C. except for one piece which was removed after one hours treatment with peroxide. The treated pieces were then dyed in the following manner:

(a) The piece that had been given peroxide treatment for one hour and one of the pieces that had been given 4 hours treatment with peroxide were passed through the following solution (30 seconds contact time) and mangled to give 100% pick up of the dye solution by the fabric.

The thus treated fabric was kept for one hour at room temperature, then rinsed and dried. Dyeings of good depth and satisfactory fastness to washing were obtained.

(b) Another piece treated as described above with permonosulphuric acid followed by hydrogen peroxide for 4 hours was passed through the following solution at 25 C. and mangled to give 100% pick up of dye solution by the fabric (contact time: 30 seconds).

Parts by wt. Water 1000 Procion Red GS 40 Sodium carbonate 30 Tergitol TMN The thus treated fabric was kept for 1 hour at room temperature, then rinsed and dried. A dyeing of satisfactory depth and good fastness to washing was obtained.

(c) 33 parts by weight of the fabric, treated with permonosulphuric acid followed by 4 hours treatment in hydrogen peroxide as described above, was dyed in the following bath for 1 hour at 25 0.:

Parts by wt. Water 1000 Cibacron Scarlet RP 13 Sodium carbonate 30 Tergitol TMN 2 A dyeing of satisfactory depth and good fastness to washing was obtained.

The treated and dyed samples and a control were then submitted to a 60 minute washing test and the diminutions in width and length due to shrinkage determined. The results were as follows:

The severity of the washing action may be judged by the high shrinkage on the untreated flannel.

Whilst the untreated control diminished in area by 22.8% on applying the standard wash test, treatment with permonosulphuric acid followed by treatment with hydrogen peroxide for l or 4 hours and then dyeing with the same yellow reactive dyestulf respectively reduced the diminution in area to 0.6% or resulted in an increase in area of 2.2%. When samples which had been first treated with permonosulphuric acid followed by the 4 hour treatment with hydrogen peroxide were dyed with different reactive dyestuffs there were small increases in area in all cases on applying the test. The dyestuffs used belong to different chemical types of reactive dyestulf. These results are clearly similar to those reported in Examples 2 and 3.

We claim:

1. A process for reducing the tendency to felt of animal hair and materials comprising the same which comprises (a) first treating said animal hair with an aqueous solution of a permonosulphuric compound selected from the group consisting of permonosulphuric acid and watersoluble salts thereof, said aqueous solution having a pH value of less than 8 and (b) as the next essential step, treating said hair with a dilute aqueous solution of hydrogen peroxide having a pH value within the range of 6.5 to 10.5.

2. A process for reducing the tendency to felt of animal hair and materials comprising the same which comprises (a) first treating said animal hair at a temperature within the range of room temperature to 70 C. with an aqueous solution of a permonosulphuric compounds selected from the group consisting of permonosulphuric acid and water-soluble salts thereof, said aqueous solution having a pH value Within the range of 0.1 and 8.0 and (b) as the next essential step, treating said hair with a dilute aqueous solution of hydrogen peroxide having a pH value within the range of 6.5 to 10.5 and a temperature within the range of room temperature to 60 C.

3. The process of claim 2 in which the hydrogen peroxide solution has a pH value within the range of 8.0 to 9.0.

4. The process of claim 2 in which the animal hair is wool.

5. A process for the production of coloured shrinkresistant animal hair and materials comprising the same which comprises (a) first treating said animail hair at a temperature within the range of room temperature to 70 C. with an aqueous solution of a permonosulphuric compound selected from the group consisting of permonosulphuric acid and water-soluble salts thereof, said aqueous solution having a pH value within the range of 0.1 and 8.0, (b) as the next essential step, treating said hair with a dilute aqueous solution of hydrogen peroxide having a pH value within the range of 6.5 to 10.5 and a temperature within the range of room temperature to 60 C. and (c) then applying to at least selected areas of the thus treated animal hair a composition comprising water, a water-soluble form of a reactive dyestuif and an acid acceptor, said composition being maintained at a temperature within the range of room temperature to 60 C. during contact with said hair.

6. The process of claim 5 in which the hydrogen peroxide solution has a pH value within the range of 8.0 to 9.0

7. The process of claim 5 in which the animal hair is wool.

8. The process of claim 5 in which the animal hair is human hair.

9. Animal hair having a reduced tendency to felt which has been produced by (a) treating animal hair with an aqueous solution of a permonosulphuric compound selected from the group consisting of permonosulphuric acid and water-soluble salts thereof, said aqueous solution having a pH value of less than 8, and (b) as the next essential step, treating said hair with a dilute aqueous solution of hydrogen peroxide having a pH value within the range of 6.5 to 10.5.

10. Animal hair having a reduced tendency to felt which has been produced by (a) treating animal hair at a temperature within the range of room temperature to 70 C. with an aqueous solution of a permonosulphuric compound selected from the group consisting of permonosulphuric acid and water-soluble salts thereof, said aqueous solution having a pH value within the range of 0.1 to 8.0 and (b) as the next essential step, treating said hair with a dilute aqueous solution of hydrogen peroxide having a pH value within the range of 6.5 to 10.5 at a temperature within the range of room temperature to 60 C.

11. Wool having a reduced tendency to felt which has been produced by (a) treating wool at a temperature within the range of room temperature to 70 C. with an aqueous solution of a permonosulphuric compound selected from the group consisting of permonosulphuric acid and water soluble salts thereof, said aqueous solution having a pH value within the range of 0.1 to 8.0 and (b) as the next essential step, treating said wool with a dilute aqueous solution of hydrogen peroxide having a pH value within the range of 6.5 to 10.5 at a temperature within the range of room temperature to 60 C.

12. Coloured shrink-resistant animal hair which has been produced by (a) treating animal hair at a temperature within the range of room temperature to 70 C. with an aqueous solution of a permonosulphuric compound selected from the group consisting of permonosulphuric acid and water-soluble salts thereof, said solution having a pH value within the range of 0.1 to 8.0, (b) as the next essential step, treating said hair with a dilute aqueous solution of hydrogen peroxide having a pH value within the range of 6.5 to 10.5 at a temperature within the range of room temperature to 60 C. and (c) thereafter applying to at least selected areas of the thus treated animal hair a composition comprising water, a water-soluble form of a reactive dyestulf and an acid acceptor, said composition being maintained at a temperature within the range of room temperature to 60 C. during contact with said hair.

13. Coloured shrink-resistant Wool which has been produced in the manner claimed in claim 12.

14. Coloured human hair which has been produced in the manner claimed in claim 12.

References Cited UNITED STATES PATENTS OTHER REFERENCES Speakman et al.: Nature, p. 1035, Dec. 10, 1938. Whewell et al.: Journal of Textile Institute, vol. 40, p. 779 (1949).

J. TRAVIS BROWN, Acting Primary Examiner.

NORMAN G. TORCHIN, Examiner.

I. CANNON, Assistant Examiner.

Claims

1. A PROCESS FOR REDUCING THE TENDENCY TO FELT OF ANIMAL HAIR AND MATERIALS COMPRISING THE SAME WHICH COMPRISES (A) FRIST TREATING SAID ANIMAL HAIR WITH AN AQUEOUS SOLUTION OF A PERMONOSULPHURIC COMPOUND SELECTED FROM THE GROUP CONSISTING OF PERMONOSULPHURIC ACID AND WATERSOLUBLE SALTS THEREOF, SAID AQUEOUS SOLUTION HAVING A PH VALUE OF LESS THAN 8 AND (B) AS THE NEXT ESSENTIAL STEP, TREATING SAID HAIR WITH A DILUTE AQUEOUS SOLUTION OF HYDROGEN PEROXIDE HAVING A PH VALUE WITHIN THE RANGE OF 6.5 TO 10.5

5. A PROCESS FOR THE PRODUCTION OF COLOURED SHRINKRESISTANT ANIMAL HAIR AND MATERIALS COMPRISING THE SAME WHICH COMPRISES (A) FIRST TREATING SAID ANIMAL HAIR AT A TEMPERATURE WITHIN THE RANGE OF ROOM TEMPERATURE TO 70*C. WITH AN AQUEOUS SOLUTION OF A PERMONOSULPHURIC COMPOUND SELECTED FROM THE GROUP CONSISTING OF PERMONOSULPHURIC ACID AND WATER-SOLUBLE SALTS THEREOF, SAID AQUEOUS SOLUTION HAVING A PH VALUE WITHIN THE RANGE OF 0.1 AND 8.0 (B) AS THE NEXT ESSENTIAL STEP, TREATING SAID HAIR WITH A DILUTE AQUEOUS SOLUTION OF HYDROGEN PERIOXIDE HAVING A PH VALUE WITHIN THE RANGE OF 6.5 TO 10.5 AND A TEMPERATURE WITHIN THE RANGE OF ROOM TEMPERATURE TO 60*C. AND (C) THEN APPLYING TO AT LEAST SELECTED AREAS OF THE THUS TREATED ANIMAL HAIR A COMPOSITION COMPRISING WATER, A WATER-SOLUBLE FORM OF A REACTIVE DYESTUFF AND AN ACID ACCEPTOR, SAID COMPOSITION BEING MAINTAINED AT A TEMPERATURE WITHIN THE RANGE OF ROOM TEMPERATURE TO 60*C. DURING CONTACT WITH SAID HAIR.