US2836543A - Sulfite hair waving composition comprising a nitrogen-containing compound and a substituted aromatic compound as additive, and method of use - Google Patents

Description

May 27, 1958 c, w so 2,836,543

SULF'ITE HAIR HAVING COMPOSITION COMPRISING A NITROGEN-CONTAINING COMPOUND AND A SUBSTITUTED AROMATIC COMPOUND AS ADDITIVE, AND METHOD OF USE Filed May 27, 1954 2 Sheets-Sheet 1 INVEN TOR. PflL/L C. Warm/v 4 OAPNEY STRESS, GRAMS Filed May 27. 1954 P. c. WATSON 2,836,543 SULFITE HAIR HAVING COMPOSITION COMPRISING A NITROGEN-CONTAINING COMPOUND AND A SUBSTITUTED AROMATIC COMPOUND AS ADDITIVE, AND METHOD OF U55 2 Sheets-Sheet 2 --30% FORMAMIDE, 8%N0 S O 0.5% GENTISICACID, H=7.0 TYPICAL THIOGLYCOLATE COMPOSITION 5 IO I5 3O 4O ELONGATION JNVENTOR. D404 6. W47'50A/ BY I A ORNEY Patented May 27, 1958 free SULFITE HAIR WAVING COMPOSITIGN COMPRIS- ING A NITROGEN-CONTAINING COMPOUND AND A SUBSTITUTED AROMATIC CGMPUUND AS ADDITWE, AND METHOD F USE Paul C. Watson, North Quincy, Mass, assignor to Arthur D. Little, Inc., Cambridge, Mass, a corporation of Massachusetts Application May 27, 1954, Serial No. 432,710

7 Claims. (Cl. 167-'-87.1)

This invention relates to the treatment of hair, and more particularly to the treatment of hair to cause it to conform to a predetermined configuration, which configuration will return upon drying after repeated wetting with water.

So-called cold waving of hair has been practiced for several years with considerable consumer acceptance. The basis of all of the successful cold waving formulations to date is the incorporation of a thioglycolate therein. Considerable speculation and research work has been directed to the determination of the action of this compound, but it is believed that the precise mechanism has not been finally determined. The process employed for waving hair consists, generally, in applying the treating agent to the hair, wrapping the hair in curlers, allowing the treatment to continue for the desired length of time (usually less than one hour) removing the treating agent, by destroying it as by oxidation, or by washing it out with water, and drying the hair. The curlers are removed before washing.

Many careful studies have shown that thioglycolic acidand ammonium thioglycolate tend to damage hair and skin by prolonged or repeated treatment. This damage is more pronounced on hair which has been bleached or dyed. The odor of thiols in general, is objectionable, and thioglycolic acid and ammonium thioglycolate are no exception. The disagreeable odors of the thioglycolates has made it undesirable and impractical to make a hair preparation which could be applied to wave, straighten, or train hair without curlers and which could be applied and left on the hair over a period of time. The lack of odor of the preparation in this invention, on the other hand, permits it to be so applied and retained on the hair over a period of time. Thus, in summary, the cold wave preparations available until now have the disadvantage of the possibility of hair damage, disagreeable odor, and incapability of being used as a hair treatment to be left on the hair for a period of time.

Soluble sulfites, including sodium bisulfite, have been employed as hair treating agents, but their action is so slow at room temperature as to preclude their use as the cold waving agent.

Other agents and combination of agents have been employed for waving hair at room temperature, but they are either too severe in their action, or have other disadvantages, such as unpleasant odor. It is known that ammonium sulfide and thioglycerol wave hair well, but they are toxic.

It is to be understood that the term hair treating, as hereinafter used, includes curling or waving, straightening, training and any other treatments which give the hair desired configurations.

It is an object ofthis invention to prepare a hair treating composition which can be effectively employed at room temperature. I

Another object is to prepare a hair treating composition which acts more rapidly than the so-called cold wave com- Water.

positions now employed. This is accomplished by the use of an additive.

Still another object is to prepare a hair treating composition which is substantially odorless.

A further object is the preparation of a hair treating composition whichdamages hair less than those now in use.

Still another object is to prepare a hair treating composition which exhibits less wash-ou i. e., retains the curl over a larger number of washings.

Another object is to prepare a solution which readily swells hair at room temperature thereby rendering the hair amenable to permanently setting it in a predetermined configuration.

These and other objects, will become apparent hereinafter.

Hair is composed of keratin, and keratin is largely made up of relatively long chain polyamides cross linked by disulfide linkages. the straightening of curled hair, it is necessary first to break the disulfide linkages and then to swell the thus modified fiber. I have found that a soluble bisulfite such as an alkali metal bisulfite, is particularly useful for this purpose. Sodium bisulfite and sodium metabisulfite, N21 S O (which hydrolyzes in the presence of water to yield Natl-I50 have been found to be particularly effective.

As in any setting operation, the swelled and chemically reduced fiberis placed in the predetermined position desired, and the reducing agent is neutralized with an oxidizing agent, such as potassium bromate; the resulting product and the swelling agent are removed by washing with The fiber so set, permanently assumes the altered shape and remains thus fixed indefinitely.

In accordance with this invention, I provide a composition comprising a mixture of a water-soluble sulfite as the agent for breaking the disulfide linkages, as a swelling agent a water-soluble nitrogen containing compound of the amide or imide class and an additive chosen from a group of polyfunctional aromatic compounds of the proper concentrations and the proper pH and a method of applying the composition to the hair. an excellent hair treating formulation in that it permits training hair or setting it to a desired configuration in a short period of time without the use of solutions having undesirable odors or harmful effects on the hair.

The sulfite introduced into the mixture may be most conveniently a bisulfite, such as sodium bisulfite, sodium metabisulfite (which hydrolyzes in the presence of water to yield sodium bisulfite), potassium bisulfite, ammonium bisulfite, or an amine bisulfite, suchas normal propyl amine bisulfite.

The amide or imide must be water-soluble to the ex- 7 and their alkyl and alkanol substituted derivatives. These analogs are those derived by displacing one or more of the three substituents on the carbon atom of formic acid with ammonia. The ester group, may be attached through the hydroxyl group ofthe formic acidmolecule. The alkyl and alkanol substituents' are desirably substituted in place of the hydrogen atom of formic acid, although they may be substituted on the ammonia substituents. The alkyl and alkanol substituents should not exceed four carbon atoms when taken together. In the case of guanidine, which is the tri-ammonia analog of formic acid, it is preferable that there be no further substituents on the compound.-

In the waving of straight hair, or.

This serves as wherein Xis a member of the group consisting of hydrogen,'alkyl and alkanol radicals containing not more than 10 Some;of the particularly effective nitrogen-containing components for the purpose of the present invention may. be defined as those represented by the formula three carbon atoms, the radical waist-NH.

wvhere injz is thelinteger one or two, NR R;, and OR, 15

whereinR anjalkyl radicalcontaining not more than three carbon atoms. The groups R R R .and R are members of the class consisting'of'hydrogen, alkyl and betweenc. and 7 and the preferred pH is 6.8. If the'pH exceeds about 7.5 or 8, the wet curl retention-drops materially, and if it is above 9, the action of alkali be- 7 comes harmful. 35

The concentration of both sulfite and amideis also importanti "Themost' effective range for sulfite, based on the S content by weight, is from 2.0% to 10% of the totalcomposition, while'the preferred range is from about 5%..to 7.0%. .The most effective range of the 40 amide .isfrom to 40%, and the preferred range.

from to 3 5%, although about has: been found 1 to be the'optim'um concentration. .The desired pH may i be obtained-byadding an alkali' such 'as'NaOH or by and sodium metabisulfite using a mixture of sodium sulfite in the proper proportions.- w I g V The concentrations of the sulfite and amides are, however, directly dependent upon .each other, thus making it inadvisable to choose concentrations from eachof the ranges stated v without giving consideration to theover-all concentration of: the solution.

sulfite, an exceptionally-effective hair setting or treating solution. is,-forrned, but the amide might salt out and crystallize} on the hair. Thus,'the combined:s'olubilityof these components at room temperature (or slightly below) becomes-an important'factorin the determina-- 7 Ttion of concentrations, for it is; undesirable that there be any solids present at normal room temperatures" in a hair treating solution., Generally, as the amide concentration a is ncreased, the sulfite concentrattonmust be-decreased.

Using urea andsodium metabisulfite (Na S O as an 'exfample, it has been found that the concentrations listed below arethe most efie'ctive at 25 and at a pH of 6.8.-

7 4 1 Percent by Percent by SOgedutv- V fweight'of *weight; 1 alent' 'fUreaj Na S Oa' weight) 7 e. is -1"10;1 q

a a 30 6130115 4110 8.4' '40 3to9 2mm *3 raw-am ss.wea 1 1 5 The preferredenitrogen containing components;- include formamide, HCONH2; ;urea, n nconrn; urethane,

I 7 Thus,if high -concentra-- 'tions of amide are used along with the higher limits of C2H5QCONH2; and acetamide,- cn coNn and. will].

hereinafter be referred to as the amide component.

Although'compositions of the type and ranges discussed above are effective hair treating solutions, they are relatively slow and dependent upon temperature. tion time of these compositions of sulfite and amide may,

however, be speeded up materially by the/use of a small quantity of an additive.

The reasons for the marked'improvement in hair treating brought about by the use of an additive is not known, but thirty-minute waving efliciencies up to 74% have been attained with additives as compared for 48% for a similar composition Without an additive. r

Additives which have been found satisfactory for the compositions of this invention are substituted aromatic compounds such as py'rocatechol, p-methyl aminophenol sulfate, phenyl hydrazine, gentisic acid, l-hydroxy-2- 'naphthoic acid, gallic acid, anthranilicgacid', benzilicjacid and salicylic acid.

Some of the, particularly effective additives for thepur pose of the present invention may be defined as. those 7 represented as substituted aromatic hydrocarbons containing no more than two benzene rings and having two or more substituents taken from the group of 0H,. COOIL, NH substituted NH C l-I andsubstituted C H Or-i' 'ganic salts formed by the addition of inorganic. acids to these substituted aromatics are also satisfactory. The

choice of an additive from this group of substitutedaromatics must, of course, belimited to those. compounds whicharenotskin irritants and which are not toxic when applied externally in the percentage inwhich they are employed.

(HO) C H COOH). is preferred, while l-hydroxy-Z- naphthoic acid (C H (OH)COOH) is almost as eflec-J: tive.

Amide concentrations Additive concentrations should not be lowerthan;0;5

nor exceed about 6%by weight ofthefcomponents and should preferably be kept within therange between about J 1 and 4% by weight dependingupon theparticularxadditive.- The preferable concentration for gentisic. acid; for

is2% while that for. LhydroXyQ-naphthoicacid.

example, is 4% The, amide may-be premixed with the sulfite, andf additive, and dispensed as a ready-made solution; concentrated solutions may be made up separately ofthe amidecomponeut and of the sulfite and additive mixed or the amide may; be bottled as 'a water solution'and the. remaining ingredients packaged as a dry powder. Since formamidc mixed with sulfites has atendcncy to 'lose' its effectiveness as acomponent in the hair treating composition of this invention after storage, 'formamide-containing'composi-. tions should preferably be packaged in the third-named V mannerJ a e The temperature at which these solutions are used is limited usually'ito a range between room temperature, or .slightlyjlower, andlbody'temperatnre'. This meansja-tem pcrature range ofabout 20. to 30 C. Temperatures above body temperatures may conceivably-be used up to a comfortable maximum, perhaps as high as 37 4O;C.

As the temperature increases, thefetfectivenes'sj ofthe solution, in terms of wet curl retention, increases. ,At H .the 'higher.concentration, the'rate of increase in etfe'c-j., l

"tivenes's ;is even moremarked at high temperatures. The i timeof exposure of the hair to the solution dependsjupon f the temperature used, the-effectiveness of the particular ,7 solution and the degree of curl retention desired. Nor- The reac- It is preferable that the additive is-not highly colored. 4 i ,5 Among those additives suitable for the purposes ofrthis invention, gentisic acid '(2,5-dihydroxybenzoic acid,

above 40% by weightzhave-been found to 'have'a deleterious effect on the hairycausing; cxcessiveswelling of the: keratin of the hair... In fact; above about 40% amide concentrations, the damage to: hairis so severe that hair waving compositions should' be limited .to concentrations below that figure. l' z mal exposures are of the order of 30 to 90 minutes.

it is desirable to stop the action of the treating solution by the use of a neutrsh'zer. Such a neutralizer should be capable of removing the sulfite ion and must not, of course, be harmful to the hair or skin. Examples of neutralizers include water and mild oxidizing agents such as a dilute solution of perborate or alkaline bromate.

Experimental work has shown that the degree of curl retained permanently depends upon the amount of swelling imparted to the hair while wrapped on curlers and the degree to which the shrinkage of the hair is subjected by the oxidizing agent and subsequent removal of the compounds by washing. Unless the hair is swelled at least 18%, adequate permanent set cannot be obtained by the process of this invention. Swelling action far in excess of 13% may be readily secured. Hair varies in thickness and in chemical composition so that hair from difierent sources will swell to varying extents with a given treatment under identical conditions. The concentration of soluble bisulfite required to break the disulfide linkages and the concentration of the swelling agent required to impart a desired degree of swelling of hair also depends upon the quantity employed. In general, the swelling action increases with increasing concentration and as the pH of the mixture approaches 7.0. Under usual conditions encountered in hair waving sufl'lcient swelling is obtained with 5% sodium bisulfite and 1% sodium bisulfite may be employed in some instances. The concentration of swelling agent must be sufiicient to cause at least 18% swelling within one hour under the usual conditions, as stated above, but swelling in the order of 30% to 80% within one hour at room temperature is preferable for the usual treatment. Swelling of hair in excess of 80%, and particularly in excess of about 110%, requires care in its management since the hair becomes so greatly weakened that it may break if handled improperly.

The measure of the effectiveness of a hair waving solution is the degree to which the curl is retained after treatment. Thus, the minimum concentrations of amide and bisulfite are dictated by an acceptable degree of curl re tention. Such minimum concentrations are about amide by weight and about 2% S0 equivalent by weight. Below these concentrations, cur-l retention is very low.

Because curl retention is the important factor in making a desirable cold wave solution, a means for accurately measuring this property has been devised. The means are shown in Figs. 1-4.

Fig. l is a bundle of about 50 parallel strands of straight hair to be tested. Fig. 2 is a perspective view of a device for curling hair; Fig. 3 is the same view wherein the device is surrounded by a wetted web; Fig. 4 is a View of a typical flat curled swatch of hair, and Fig. 5 is a graph showing the marked decrease in hair damage achieved by the composition of this invention as compared with a typical thioglycolate solution.

A bundle of about 50 parallel strands of individual hairs, Fig. l, is processed at a time. The bundle is combed so that the strands are parallel.

Referring now to Fig. 2, one end of the bundle 13 is bent over the end of waving-form 12 and attached as by an elastic band 14. The bundle is then bent around pegs 15, as shown, bent over the other end of waving form 12, and secured as with elastic band 15. After the hairs have been arranged on waving form 12, a narrow .rip of blotting paper 17, as shown in Fig. 3, is Wound around the pegs and held in place by an elastic band 18.

The blotting paper 17, is saturated with waving lotion, thus wetting the bands of hair and keeping them wet over the desired treatin period. The whole form with the hair. is then left at a fixed temperature for the time desired. After exposure to the waving solution for a specific length of time, the wave formed is immersed in water or in a neutralizer which may he a mild oxidizing compound, the straight ends of hair are cut at positions 21 and 22 on wave form 12, Fig. 2, and the entire bundle of hair springs is floated on water.

A value for what is termed wet curl retention is determined immediately after the hairis placed in the water and again after a specified length of time (generally thirty minutes). The bundle of hair is measured to obtain the length of the bundle of springs, usually the distance between the centers of the first and last, or next to the last, crests; for example, between the peak of crests 1? and 20, Fig. 4. This distance is compared with distance between the centers of the corresponding pegs of the waving form, and the result is called the wet curl retention. This is calculated by the formula:

where L=drawn-out length of a strand of hair used to span the distance from the center of the two pegs selected on the waving form;

L'=length of hair springs after curling measured from the center of the two crests corresponding to the centers of the two pegs selected on the waving form; and

l=distance between the centers of the two pegs chosen on the waving form.

Wet curl retention is taken as the true measure of the efiectiveness of the waving solution, inasmuch as many substances, including water, will impart a curl which will be retained as long as the hair remains dry.

Fig. 5 illustrates the achievement of less damage to the hair by use of a typical composition of this invention. in Fig. 5 percent elongation is plotted against stress which was applied to a hair strand after subjection to a solution or" 30% formamide, 8% Na S O 0.5% gentisic acid (pH-=7.G) for 30 minutes and subsequent neutralization with water. For example, at approximately the inflection point, about 7.5 elongation, around 1.38 gms./ denier are required for hair waved with the formamide-sulfite-gentisic acid composition while only 0.93 gm./denier are required for hair waved with a typical thioglycolate solution. The added stress required is a measure of hair strength and thus a measure of decreased hair damage. Thus, the formamide-sulfite-gentisic acid composition of this invention shows a decrease in hair damage of about 48% over the commonly used thioglycolate composition.

This decreased hair damage shown by the sulfite-amideentisic acid composition is unexpected since it is known that with such compositions containing in excess of 40% amide, the protein in hair can be dissolved and destroyed. Thus, by the dilution of the composition to the ranges used in these hair treating compositions, the possibility of hair damage is reduced to below the now acceptable imits of the compositions currently in use. The reasons for this practical elimination of hair damage brought about through dilution are not known, but are clearly illustrated in Fig. 5.

The following examples are illustrative of the type of cold waving solutions which have been found to achieve the objects of this invention. This invention is not, however, limited by these examples.

TEMPLE l water. Maximum wet curl retention, obtained at a pli of 6.8 (adjusted by adding NaOI-I), was 68% compared with 48% for the same solution without the gentisic acid.

EXAMPLE 2 A solution of 30% formamide, 10% sodium metabisulfite and 20% gentisic acid was made up in water and justed to pH 7.0 with sodium hydroxide.

' 7 EXAMPLE 3 A solution of 30% urethane, 7.5% sodium nietabisulfiteand 3% l-hydroxy-Z-naphthoic acid was made up in water and strands of hair subjected to this solution for 30 minutes "by means of the waving form device .described. neutralization was done with water. Maximum curl retention, obtained at a pH of 6.8. was 65%. I V

EXAMPLE 4 'A solution of 40% acetamide, sodium metabisulfite, and 2% gentisic acid was made up in water and ad- Strands of hair were subjected to this solution for 30 minutes. at C. by means of the waving form device described. Neutralization was. done with water. A curl retention of 50% was obtained. y

' A large number of additional composition containing additives were made up and evaluated in the manner described in Example 1. The improvements in -minute waving efiiciency are shown in the tabulation below:

Additives to urea bisulfite formulations efiect jon hair treating efiiciency at 25 C.

[Additives to 30% urea, 7.5% sodium metabisulfite at pH 6.8.}

. 30-Minute Additive Percent Waving 7 1 Additive Eificiency,

' Percent None-blankcontrol 48 1,2-benzenediol 2 1 74 p-methylarninophenol sulfate 4 p-aminophenol H01 1. 5 72 p-aminoacetanilide. '1 71 2,5-dihydroxybenzoic acid (gentisic acid). t 2 V 68 1-hydroxy-2-naphthoic acicL 4 67 p-amino salicylic acidl 2 67 5-amino salicylic acid--. A 2 6T 3,4,5-trihydroxybenzoic acid (gallic acid)- 1 I66 O-aminobenzoic acid (anthranilic acid) 2 66 diphenylglycolic acid (benzilic aoid) 0. 5 65 ,O-hydroxybcnzoic acid (salicylic acid).. 7 6 62 I claim: 7

maintained at a pH between about 6 and 75 of a s'ulfite,

a nitrogen-containing component and an additive, the

combinedisolubility of which is such that no appreciable Temperature wasmaintained at 25 C., and

' mined configuration at temperatures between about 20 and salting out. or the components will occur on said hair at temperatures above about20 C said sulfite being present in a concentration equivalent to from about. 2

to 10% by weight S0 of said solution, said nitrogen containing component being present in. a concentration equivalent to from about 15 to 40% by weight of said solution andhaving'the formula V RIz V 7 ll T' .7

wherein X is a member selected 'from the group consisting of hydrogen, alkanol and alkyl radicals contain-f ing not more than 3" carbon atoms the radical fac t-them '1 wherein R is' an alkyl radical containing not'mo re than '3 carbon atoms, and -'NRi R R R ,'R and k being,

members of the class consisting-ct hydrogen, alkyl and alkanol 'radicals'which when taken together shall contain 'wherein'X is a'member selected from the'group con not more than 4 carbon atoms, and Z is a member selected from the class consisting of oxygen and :NH;

said additive being present in-a concentration equivalent to from about 0.5 to 6% by weight of said solution two benzene rings and containing not less than two substituents taken from the group of OH, COOH, NH

substituted NH (3 1-1 and substituted C H 2. A liquid compositioniu'accordance with claim 1 wherein said additive is gentisic'acid.

3. Aliquid composition in accordance with claim 1 wherein said additive is l-hydtoxy-Z-naphthoic acid.

74.1% liquid composition for setting hair ina predeter- 40 C. without effecting any appreciable injurious swelling of said hair comprising an aqueous solution of an alkali metal bisulfite, urea and gentisic acid, the pH of said composition being adjusted to between 6 and .7, said alkali'metal bisulfite being present in a concentration equivalent to 3 to 6 percent S0 by weight of said solu;

tion, said urea being present in a concentration equivalent to from about 15 to'40% by weight of said solution and .said gentisic acid being present in an amount'equivalent ;to' from 1 to "4 percent by weight of said solution,-fthe combined solubility of said alkali metal bisulfite, said urea and said gentisic'acid being such that no appreciable salting out will occur on saidhair at temperatures above a and 40 C. without eifecting any appreciable injurious welling of said hair comprising an aqueous solution of 10 percent by weigh't sodium' metabisulfite, 30 'percent by weight formamide and 2 percent by weight gentisic acid and having a pH of 6.8 p a 7 V 7. The process of permanently setting hair in a predetermined configuration Without etfecting any'appreciable injurious swelling of said hair, comprising the steps of adjusting said hair to the desired configuration, contact-' ing said hair for a period of frorn about thirty to ninety minutes maintained at a temperature between about 20 and 40? vC. with a water solution of a sulfite, a nitrogen-containing component and an additive; thexcombined solubility of which'is such that no appreciable salting out.

.of the components will occur above about 20 C., treat: a sing said hair with a mild oxidizing agent, andwash- 2 ing said hair with watergsaid s ulfite" being present in a 1 concentration equivalent to from about 2 'to 10% by" weight SO of said solution,- said nitrogen-containing component being present in a concentration equivalent'to from about 15 to. 40% by weight of said solution and having the formula.

sisting of hydrogen, alkanol and alkyl radicals; containing not more than 3 'carbonfatomg'the radical wherein n is the integer selected from l and'Z, -J.OR,' wherein R1is an alkyl radical containing not'more than 1 3 carbon atoms. and NR R R RZ R andR being .l' members of the class consisting of hydrogem'alkyl and alkanol radicals which when taken together shall contain j "not more than 4 carbon atoms} and Z is a memb'er's'elected from the class consisting ofoxygen and =NH;

said additive being present in a concentration equivalent to from about 0.5 to 6% by weight of said solution and being selected from the group consisting of substituted aromatic hydrocarbons and acid salts thereof, said substituted aromatic hydrocarbons having no more than two 5 benzene rings and containing not less than two substituents taken from the group of OH, COOH, NH:, and substituted C H References Cited in the file of this patent UNITED STATES PATENTS 2,437,965 Michaels et a1. Mar. 16, 1948 2,445,028 Jones et a1. July 13, 1948 2,717,228 Brown Sept. 6, 1955 15 10 FOREIGN PATENTS Switzerland Ian. 16, 1951 Belgium July 14, 1951 Great Britain Feb. 20, 1936 Switzerland Dec. 1, 1947 France Nov. 4, 1937 OTHER REFERENCES Jones et al.: The Dispersion of Keratins, 11, Studies 10 on the Dispersion of Keratins by Reductions in Neutral Solutions of Protein Denaturants, Arch. Biochem., December 1943, pp. 193-202.

Claims (1)

1. A LIQUID COMPOSITION FOR SETTING HAIR IN A PREDETERMINED CONFIGURATION AT TEMPERATURES BETWEEN 20 AND 40* C. WITHOUT EFFECTING ANY APPRECIABLE INJURIOUS SWELLING OF SAID HAIR, CONSISTING ESSENTIALLY OF A WATER SOLUTION MAINTAINED AT A PH BETWEEN ABOUT 6 AND 7.5 OF A SULFITE, A NITROGEN-CONTAINING COMPONENT AND AN ADDITIVE, THE COMBINED SOLUBILITY OF WHICH IS SUCH THAT NO APPRECIABLE SALTING OUT OF THE COMPONENTS WILL OCCUR ON SAID HAIR AT TEMPERATURES ABOVE ABOUT 20*C., SAID SULFITE BEING PRESENT IN A CONCENTRATION EQUIVALENT TO FROM ABOUT 2 TO 10% BY WEIGHT SO2 OF SAID SOLUTION, SAID NITROGENCONTAINING COMPONENT BEING PRESENT IN A CONCENTRATION EQUIVALENT TO FROM ABOUT 15 TO 40% BY WEIGHT OF SAID SOLUTION AND HAVING THE FORMULA

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