US 3155624 A
Description (OCR text may contain errors)
United States Patent Ofi ice 3,155,624 Patented Nov. 3., 1954 This invention is concerned with a novel process for the manufacture of superfatted transparent soap and with the products obtained by the process which also possess all the desirable properties of the highest quality milled soap.
Although it has been appreciated that soaps ordinarily identified as milled soap have some small degree of translucency, they have no transparency and are not considered by those skilled in the soap art as transparent soaps. Soaps are known in the art as transparent soaps, however, and some have enjoyed for many years a limited commercial appeal. Such soaps, however, are expensive due to the method of making them, and those so-called transparent soaps which attempted to use cheaper methods of production are no longer found to be acceptable by present day commercial standards.
One method used in the production of the more acceptable type of transparent soap is to prepare a soap base of reduced moisture content and then dissolve the soap in alcohol, removing the saline impurities by decantation. Alcohol is recovered from the soap by distillation. The soap mass is then cooled to solidify and mold. This method is expensive, time consuming, and involves the use of a high cost solvent. 7
A cheaper method for manufacturing a transparent soap used the well known cold process technique. Tallow which is low in free acid, coconut oil and rosin are saponified with caustic soda in the presence of alcohol or alcohol and glycerine or in the presence of a sugar solution, and the soap mass recovered and molded.
Another method involves the semi-boiled process and includes crutching the initial oils and fats at approximately 140 F., saponifying with caustic, then adding lye, and stirring until the soap has reached a desired consistency. This is followed by adding sugar dissolved in water, or alcohol and glycerine or combinations thereof. The mass is again crutched at about 160 F., and desired perfume and dyestuff added. The soap mass is molded by framing, then slabbed, cut and pressed. It is well known that neither the cold process nor the semi-boiled process produced soaps of high quality.
Prior art processes for the production of transparent soap are discussed by F. W. Wells in Soap and Chemical Specialties, volume XXXI, No. 6 and No. 7, June and July 1955. As is mentioned in these articles, a transparent soap should be sutliciently transparent to permit boldfaced type of about 14 point size to be read easily through a thickness of a quarter inch. It is with reference to this standard that the term transparent is used in this application in describing products of the present process.
The incorporation of free fatty acid, such as palmitic, stearic acid, and others into a transparent soap bar to attempt to form a superfatted transparent soap bar would be desirable in that it eliminates free alkali, lowers the pH and generally makes the soap milder. It also improves the lathering characteristics of the bar. The addition of free fatty acid to the soap bar, however, has a major disadvantage in that it softens thebar usually to such an extent that the moisture content must be lowered to make the bar commercially acceptable. Moreover, the presence of free fatty acids makes it difiicult to process the bar during plodding and stamping and destroys the transparency.
In accordance with the present invention these poor characteristics of superfatted soap barsare eliminated and superfatted transparent soap bars are obtained with all the desirable properties of the highest quality milled soap. This is achieved by the addition to a 'superfatted soap of a polyhydric alcohol, such as glyoerine,.sorbitol, sugar and pentaerythritol. The presence of a polyhydric alcohol in superfatted soap toughens it so that it can be milled and plodded in the normal manner. In most cases superfatted bars made with polyhydric alcohol are more transparent than bars made of the same base without superfat, with or without polyhydric alcohols. This'is surprising since at room temperature stearic acid is a white opaque solid and most solids with these physical properties would opacify the bar.
The amount of free fatty acid that can be added is dependent on the amount of polyhydric alcohol used. When the free fatty acid content is increased, the polyhydric alcohol content must also be increased. For best results the quantities of each should be about equal, but the presence of more polyhydric alcohol than free fatty acid will not generally hurt the transparency. On the other hand, if much more free fatty acid than polyhydric alcohol is presentin the soap bar, it tends to become soft and loses transparency. The free fatty acid content should not be more than 1% greater than the polyhydric alcohol content, both amounts being by weight of the finishedbar. For example, if a bar contains 3% free fatty acid, it will not be transparent unless at least 2% polyhydric alcohol is present in the bar. In general the sup'erfatted transparent bars will contain from about 1% to about 5% by weight of free fatty acid, and polyhydric alcohol in an amount up to about 10% by weight. p
The salt and moisture limits to obtain transparency of the superfatted bars are not as critical as for non-superfatted bars. In general the moisture content of the finished bars will be in the range from about 17% to about 22.5% by Weight and the salt content thereof will be from amount up to about 10% by weight.
The primary advantage of the method'of this invention is that it makes possible the economical production of a superfatted transparent soap having excellent lathering properties, firmness and a smooth appearance and waxy feel. The superfatted transparent soap can be produced without waste or time loss and with minimum cost. There is no solvent used which must be recovered. No unusual equipment not available in ordinary soap making is required. 5 I
The superfatted transparent soap produced by the present invention has a pleasing firm yet velvety texture; During washing it does not form a'mushy' coating on its surface, and does not mar the appearance of the soap dish. It does not tend to form unsightly cracks, as is the case with many milled soaps. If the soap of the present invention is maintained for considerable lengths of time J in contact with water, as happens occasionally'when an incompletely dry soap dish is used, 'it may become' cloudy as to that contacted portion, but the soap, upon removal from such contact, will return to its original firmness" and transparency. Furthermore, and most surprisingly, bars of soap made by the process of this invention have the very desirable and unique advantage that they may he used even though worn to wafer thinness. Waste is therefore: avoided. i Soaps may range from opaqueness through a translucency into true' transparency, depending upon the method of manufacture. Various methods have been used to evaluate the translucency, and more specifically the transparency of soaps; A method for accurately measuring this property of a bar of soap is bythe use of the following apparatus developed for this purpose. A'bar of e "fTr'anslucency'.Voltage or TV..
" TV is, the more' translucent the bar.
soapis -placed, a completely darkened room, ontop Tof a cone section surrounding a light source of variable voltage. The conels'ection has a diameter. of /2 inch at the top and 2 /2 inches at the base, which surrounds the face of thelight; thetop of .the'cone section is 9 /2 inches above the face of the lamp, and the lamp is a microscope lamp. with a, 120-volt,- 15-watt bulb having a blue iground-glass filter; The yolta'ge across the lamp J V bulb is adjusted until the light from the top of the cone section shines through a bar having a thickness of 2.75 cm. andiormsa barely perceptible. circular outline; voltage across the bulb 'is' used as a measure of trans.- lucency, which" is independent of color and is termed Thus, the lower the It is possible to measure readily the TV at other bar thicknesses and interpolate to the standard of 2.75 cm. used herein. This method of determining translucency is believed tobe superior to a reflectance test described in the art, be-' cause -it is relatively unalfected by soap color and gloss andavoidsthe difiiculty of cutting a soap bar to a required thickness of only of an inch.
For purposes of comparison, an ordinary milled toilet V soap of good quality, even in the absence of pigments such as titanium dioxide which makes it opaque, has a, TV of greater: than 110, i'.e., it, is too opaque to be measured on the apparatus described. This is 'despite the factthat it has the sheen; and glossiness which are commonly referred toas the translucency of milled soap, to distinguish it from 'the dull nature of frame soaps. .The products of the present invention, on the other hand, have a TV of 35' or'less, generally 30 or less, when freshly made. A
' bar'of'soap with 'a TV of 30 or, less meets the standard lrequired to be called transparent. In general, with the soaps of'this invention there is an'improvement in transparency upon aging of about six days or more, and in particular it is possibleto practice our invention and produce a soap which, when fresh, may have a TV'of more than.30,,even as high; as about 35, which soap,
when aged, will ,acquirethe transparent properties of a soap of a TV ofabout, 30 or less. 'Thedilference between a bar, of'soap having a TV of 25 and one having a TV ofv 35 is quite obvious to-the unaided eye.
The mostjconvenient starting material for the present process is soap initially containing from about 28% to 'about 34%, usually approximately 30% to32%, moisture, e.g., a neat kettle soap. The precise composition of the initial stock used tov prepare the. soap is not critical 7 g as long as the composition does not differ materially from those ordinarily employed in the manufacture of'rnilled toilet soaps, 'Thus, for example, the relative proportions of fatty acids from .tallow and from coconut oil, and the relative eifeets of such ingredients on the physical characteristics of' milled toilet soap produced therefrom,
are well known'to soap makers, and this knowledge is The a temperature abovel8 F., and preferablyabove 205 F.
The crutched kettle soap, which has a moisture content of from about 28%. to 34%, usuallyiapproximately 30% to 32%, isnext subjected to a drying step. The drying is carried out to an extent which permits the desired moisture range to be obtained in the finished bar. Thedrying step .can be carried out by any of the conventional drying methods, forexample, ordinary cabinet drying, It'is, however, preferred to. use themethod commonly known as flash dryingor, most preferably, the method of tubular drying as is described in US. Patent No. 2,710,067 of Bassett and Packard. When either flash drying or tubular drying I has been'use'd, the, soap at the end of the operation. will.
.be in the molten state. 'It is" then chilled. and solidified,
I after the drying.
preferably into flakes or chips, before the mixing. There are some advantages, although not critical, in conducting.
thechilling operation rapidly. When ordinary cabinet dryingfis used, the soapwill be in solid flaky orchip' form While the free fatty acid is generally added in the crutcher, the polyhydric alcohol and salt may be added either in the crutcheror in the chip mixer discussed below. I I
The next operation is conveniently that of mixing the soap flakes. The polyhydric alcohol and salt may be added to the soap in the chip mixer. It is also a convenient time to adjust the water content and the salt'content. The condition of the soaprmass at the time of the mixing operation preferably should beone in which it will permit a, working andshearing of the mass tov be performed, For example, the soap mass should not be so hot that it is too soft or fluid to resist the operation of the mixer. For this reason, the temperature of'the soap at the beginning of the'mixing step should be below about 90 F., and preferably should be in the range of from 80 to 85F. During the mixing of stocks of usual types and. with usual mechanical equipment and time, the tem perature should not rise above about 110 F and preferably not above 104 51 I I I I At some point, preferably before the end of the mixing step, the moisture content and the salt content must be adjusted so that in the finished product, they will be within the limits discussed above. During the mixing step, small stock used. .It is, however, not necessary that this be the applicable in the formulation of the soap stock used in 1 Otheroils which may be used in place ref-coconut oil are babassu,.cohune,.murumuru, ouri'cury, "palm kernel,
and tucuna. I g a When neat kettle soap, which is in the; liquid state, is
used asthe starting material, it is first subjected to ordi-, nary crutching, during which the free fattyacids are added in order to eliminate. theifree alkali, lower the pH and form a superfattedsoap. This. crutching operation is not ;a critical feature of "the invention and may be conducted a by any conventional crutching method. The mixture during crutching is, as isconventional, in the liquid phase, at
ter mixture. An alternative method of obtaining the soap amounts of various optional ingredients are added when desired. These includesuch substances as perfume, coloring material s, lanolin, resin, and preservatives. The presence or absence of any, some, or all of these optional ingredients is not controlling to the production of a superfatted transparent soap. bar having the desired characteristics of a high grade milled soap. 1
. Neat kettle, soap is, a convenient example of the soap starting material. What is required is simply a soap mass, howeverprepared, which is capableof having its moisture and. salt contents. adjusted to the levelsdisclosed herein and tolwhich can be. added. the free fatty acids and polyhydric alcohols. Thedrying ofneat kettle soap is only one of the possible ways of obtaining such a soap andwa mass, is, forexample, the reaction between free fatty acids and alkali,to which reaction mixture wateris added or removed asrequired in order to obtain a moisture content withinthe' required range.
Particularly in the. case of neat kettle soap which has been dried by the tubular or'flash method and subsequently chilled rapidly, a satisfactory-degree of transparency is obtainable as early as during the mixing step.
'To accomplish this, the amount of soap in the mixer and the typeof mixer bladesemployed must be such that the soapotfers a high degree of resistance to the motion of the. blades; because ofthis resistance, the mechanical energy of the mixer blades is converted into heat energy, and'the desired temperature of the mixture thereby obtained without addition of heat from an external source. To obtain high degrees oftransparency duringthe mixing, the mixing is conducted for periods of time of about a half hour, the temperature thereby being raised to between 100 to 110 F preferably to between 100 F. and 104 F. Generally in commercial production it is not convenient to spend this amount of time in mixing, since the desired transparency is more conveniently obtained during the subsequent milling, which need be no more than a nominal amount. The time of mixing generally employed is therefore about 15 minutes, although as little as about 4 minutes is enough to obtain satisfactory blending in of the polyhydric alcohol, salt, and other added materials, such as perfume or dye. The amount of working required will vary somewhat depending upon the particular soap stock and the particular working device used. The mixing times mentioned above are those for a Barbour-Stockwell mixer with thick counterrotating blades. It is, however, a matter of routine testing to find the preferred conditions when other types o working are used.
It should be understood, however, that it is not critical to the process of preparing a superfatted soap bar of satisfactory transparency that any particular type of mixer be used, or that there be any mixing step at all. Rather, the type of mixer is of consequence only in those cases where it is desired to obtain a high degree of transparency during the mixing stage rather than at a diiferent stage. It should also be understood that in order to obtain a high degree of transparency during the mixing, it is necessary that the mechanical energy of the moving mixer blades be taken up by the soap in the form of heat energy. Thus, a high degree of transparency'will not be obtained during the mixing when a mixer with blades which pass through the soap without encountering'much resistance is used along with heat supplied externally.
It is detrimental to the obtainment of transparency, not only during the mixing but at any subsequent stage, to allow the temperature of the soap mass to be above about 110 F. Preferably, the temperature is kept below The working effect of mixing is preferably amplified by subjecting the soap mass to milling. A single pass over two five-roll mills is normally suificient. In order to obtain a satisfactory degree of transparency, it is critical that as the soap mass emerges from the mill it be at a temperature of from 100 F. to about 110 F., preferably from 100 F. to 104 F. Soap not already transparent becomes so during milling, provided it has the correct free fatty acid, polyhydric alcohol salt and moisture content, and provided suitable critical temperatures have been maintained. It is to be understood that a refiner of the type described in Patent No. 2,005,333 may be substituted for the usual mill rolls and mixer, assuming always that the same suitable conditions are maintained relative to the soap stock used. It is thus seen that what is required to make transparent soap by the process of the present invention is that a soap mass having the specified proportions of free fatty acid, polyhydric alcohol, salt and Water be subjected to working, its temperature raised to within the range of 100-110 F., preferably 100 F.-l04 F., and subsequently formed into bars. The working may take place during a mixing and/or a milling operation.
One of the functions of the milling operation is that the soap emerges from the mill in the form of very thin, flaky layers suitable for compacting by plodding into a bar form. The remaining steps in the conversion into bar form are not critical features, and are successfully accomplished by any conventional means. There is, however, an advantage to the use of vacuum plodding, since it most conveniently prevents air from becoming entrapped in the soap bar and thereby impeding translucency. It is advantageous that the soap leave the plodder at a temperature of from 98 to 110 F., preferably from 100 F. to 104 F. After the plodding, the soap is cut into individual cakes by usual means.
As has been mentioned above, it is critical to the process of this invention that, at least before the end of the working, the free fatty acid, polyhydric alcohol, water and salt contents be adjusted so that the finished soap has a content thereof within the range specified above. ing the milling and plodding operation, a certain portion of the water, usually an amount sufiicient to reduce its percentage in the mixture by about 2 to 3, may be lost by evaporation, and this loss must be borne in mind when the water content is adjusted.
When in the specification and the claims the term salt is employed, particular reference is made to sodium chloride, but it is also intended to include other Water-soluble, soap-compatible electrolytes such as potassium chloride and sodium sulfate.
Throughout the entire specification and in the claims, all percentages are percentages by weight.
The following examples are given solely for the purpose of illustration and not to be deemed limitations of this invention, many variations of which are possible without departing from the spirit or scope thereof. I
EXAMPLE 1 Kettle soap having a base stock of sodium tallow soap, 15% sodium coconut oil soap and containing about 32% water was charged to a crutcher. Sufficient stearic acid was added so that when the soap was dried and finished at 20% moisture it would contain 2% free stearic acid. The batch was heated to 210 F. and then dried to about 20% moisture by tubular drying, The soap was cooled and formed into chips on a chill roll and then placed in a chip mixer. Glycerine (2% of finished bar), dispersible pigments, perfume, salt to total 0.6% in the finished bar, lanolin (1% of finished bar) and about 2% water (dependent on the soap chip moisture) were added to the soap and the batch mixed for about /2 hour. The soap was milled by passing it over two 5 roll mills and then vacuum plodded. The temperature off the mills and out of the plodder was about F, The bar was highly transparent and possessed good milled soap properties.
, EXAMPLE 2 For this test the final product had the same composition as in Example #1 except no lanolin was added. Soap, glycerine, and stearic acid were mixed together and dried in the molten condition using a steam heated, open Paterson mixer. The dried chips were processed by passing the soap over a three roll mill, five times, and then vacuum plodding. The bar was highly transparent, tough and waxy.
EXAMPLE 3 A bar was made as in Example #2 but no glycerine was added. This comparative bar was very soft and had poor translucency, thereby illustrating the importance of hav-. ing a polyhydric alcohol present in the bars of the invention.
EXAMPLE 4 Kettle soap (85% sodium tallow soap), 15% sodium coconut oil soap, 32% E 0, glycerine (2% on finished bar), stearic acid (2% on finished bar) were mixed in a crutcher at 210 F. and tubular dried to 22% H O. There was no salt in this mixture. A series of bars were made by the finishing process as in Example #2 at various salt contents. The results were as follows: All bars contained 1% lanolin.
Bar No. Percent T.V. H2O
. as; No. 3 illustrates the 1 A was .soap
1. .acid was 2.91%, were as follows.
only 2%-glycerine was a failure.
mushy and opaque.
irnpajrtancev of the'salt content in the. superfatted transparent bars of the invention.
" EXAMPLE 5]; a
was processed as. in Example #2,
then milled and plodded into bars.- Samples were saved and then the soap was rernilled and, again plodded to lower the moisture content; this was repeated to obtain a mois ture range. The NaCl content was 0.47%. The free fatty I and the glycerine 2.25 The results percent EXAMPLE 6; f An 'attempt to make a' bar with 4% stearic acid and The soap-- was soft, I This comparative test demonstratesthat the. freefatty acid content must not be more than 1% greaterthan the polyhydric compound content, based on the final bar composition.
Y EX MPL 7 t A bar. containing.4% glycerine and 4% stearic acid.
was made by this'process. (TV==18 transparent). The bar .was tough,-waxy and transparent. H O=2O.0%.
The moisture content. of the finished bat was 22.0%; its. salt content.was. 0.45%; its 'TVfwas 20. i EXA PrEio,
vbar was made "according to the. process of thisinvention froma soap havingabasefstock of 70% sodium tallow soap andf% coconut oil 50319:" Suflicient stearic aci'd'andglycerinewere added so that the finished bar. contained 2% ,stearic acid and 3% 'glycerine. The moisture content of'ithe finished :bar was 182%; its salt content was 0.37%; its TV was 23.
EXAMPLE11 Using :an'arm immersion technique, bars containing free stearic acid and 2% glycerine were judged significantly. milder and caused significantly less burning sensatniidness. ;in-.this test the subjects' imrnersed their arms in 1% solutions of the products being tested, three times daily for '15 minute intervals. The temperature of the solution was maintained at 105 F. The test was continued until irritation developed on the subjects arms. Mildnessin the arm imrnersiontest was ezgpressed as the number of the immersions for moderate irritation to develop.- In the test the subjective reactions to the solutions regarding burning or smarting were also recorded. The data recorded in the followingtable indicate that soapj produced according to the method ofthe present invention is significantly milder than Ivory from the standpoint or subjective reactionsand development of irritation.
Mildrtess Comparison SUPERFATTED' :SOAP Vs. IVORY' BAR TRANSPARENT g i AT 1% CONCENTRATION 1 e l. Arm Immersion Rating 7 Burning Sensation Transparent Super- Ivory Trans- Trans 'fatted Soap 1 Bar No. of Equal parent Ivory parent 1N0 Diff- Subjects Mild- Super: Milder Ivory Supererence ness iatted Soap iatted Milder 7 Soap p 11 3 7 1 10' 1 o 13 10 3 0 l3 0 0 10 4 5 1 9 1 0 9 V 2 0 9 0 0 1 All the bars containcd'15% coconut oil addition bars 2 and 4 contained 1% lanolin.
' EXAMPLE 8 The following bars were made by the process described 0 in this application. The results are'listed below to further show the scope of the invention.
.. What is claimed is:
soap having a Translucency Voltage of no greater than about 35, said process comprising working below about A bar was made according to the process of this invention from a soap having a base stock of 80% sodium ft'allow soap and 20% coconut oil soap. "Sufficient stearic acid and pentaerythritol' were. added so that the finished Bar Base Stock Free Polyhydric NaOl 1120 TV No. Fatty Acid ,Alcohol 7 V 1 85% sodiumtallow 2% stearic-..-. 2% sorbitol 21.0 14 soap; 15% sodi- I 7 um coconut soap do do '2%suga-r.----- .65 19.7 22 5%stear1c. 5% glycerine..- .65 18.5 15 3% stearic 0.... .48 19.6 14 4%stear1c do .48 18.0 26 5% steario -1%g1yc no .48 20.6 4% stearie. 4% sorbito1- .48 19.6 i 19 8 -.do 2%stearic..--. 10%sugar. 48 18.0 19
: Opaque. I Y v a Bar No. 6 lllustratesthe undesirable results obtained 1100 F a toilet soap mass containing from aboutil 0% when the free fatty acldlcontent exceeds the polyhydnc to about 5.0% free soap-forming fatty acid and a Poll- ;Q Pg y more than based on t fi hydric alcohol which overcomes the adverse softening ,7 ar composl on. EXAMPLE 9 effect of the fatty acid but does not deleteniously affect 1 the transparency and processing characteristics of' the bar 'in; an; amount 'up touabout 10.0%, the quantity of said free fatty acid being at most 1% greater thanthe polyhydric alcohol content based on the final bar composition, wherein the mechanical energy is converted' bar contained 2% stearic acid and 1% penta erythritol. into heat energy by working to an extent great enough tion than Ivorysoap, aproduct having a reputation of soap, tallow soap, 2% Emersol 132 and 2% glyeerine. In
I 1. 'A process for making, a superfatted transparent to cause the mixture to rise in temperature to within a range of from about 100 F. to about 110 F., the moisture and water-soluble soap-compatible, alkali metal neutral salt content having been adjusted prior to the end of the working step to lie within the range from about 17.0% to about 22.5% moisture and an amount of said salt from about 0.2% to about 1%, and plodding the soap mass into bar form.
2. A process for making a superfatted transparent soap through which mass one-fourth inch thick, a 14 point boldface type is readable, said process comprising working at a temperature above 90 F. and below 110 F., a toilet soap mass containing from about 1.0% to about 5.0% free soap-forming fatty acid and polyhydric alcohol which overcomes the adverse softening effect of the fatty acid but does not deleteriously affect the transparency and processing characteristics of the bar in an amount up to about the quantity of said free fatty acid being at most 1% greater than the polyhydric alcohol content based on the final bar composition, whereby heat is generated throughout said mass by such working, reducing said mass at a temperature between 100 F., and 1 10 F. to a form suitable for plodding, plodding said soap mass into a bar form, the moisture and water-soluble, soap-compatible, alkali metal neutral salt content having been adjusted prior to plodding to the range of from about 17.0% to about 22.5 moisture and an amount of said salt from about 0.2% to about 1% 3. A process for making a superfatted transparent soap having a Translucency Voltage of less than 35, said value being based upon the voltage required to transmit sufficient light from a -watt, 120-volt microscope lamp through a blue ground-glass filter at a distance of 9 /2 inches, to penetrate a 2.75 cm. thickness of said soap and for a circular outline therein, said process comprising working :a toilet soap mass containing from about 1.0% to about 5.0% free soap-forming fatty acid and polyhydric alcohol which overcomes the adverse softening effect of the fatty acid but does not deleteriously affect the transparency and processing characteristics of the bar in an amount up to about 10%, the quantity of said free fatty acid being at most 1% greater than the polyhydric compound content based on the final bar composition, said soap mass having a moisture content of from 17.0% to about 22.5 and an amount of Water-soluble, soap-compatible, alkali metal neutral salt from about 0.2% to about 1%, whereby the temperature rises to not more than 110 F., reducing the mass to a ploddable form, and plodding into bars while maintaining the temperature substantially uniform, whereby a waxy textured, transparent, isotropic, microcrystalline soap is obtained.
4. A superfatted transparent soap bar made from a toilet soap mixture, containing from about 1% to about 5% free soap-forming fatty acid and in which the final soap bar contains an amount of polyhydric alcohol which overcomes the adverse softening efiect of the fatty acid but does not deleteriously affect the transparency and processing characteristics of the bar up to about 10%, from about 17.0% to about 22.5 water and from about 0.2% to about 1% water-soluble, soapcompatible, alkali metal neutral salt, the quantity of free fatty acid being at most 1% greater than the polyhydric alcohol content, which is worked within a temperature range of about F. to about F.
5. A superfatted transparent soap bar according to claim 4 which contains from about 1% to about 3% lanolin.
6. A superfatted transparent soap bar made from a toilet soap mixture, containing about 2% free soapforming fatty acid and in which the final soap bar contains about 2% glycerine, about 0.6% water-soluble, soapcompatible, alkali metal neutral salt and about 20% moisture, the quantity of said free fatty acid being at most 1% greater than the polyhydric alcohol content, which has been formed by working at a temperature from about 100 F. to about-104 F.
References Cited in the file of this patent UNITED STATES PATENTS 78,182 Brown May 26, 1868 2,298,019 Myers Oct. 6, 1942 2,686,761 Ferguson et al Aug. 17, 1954 2,781,321 Mayhew et al Feb. 12, 1957 2,970,116 Kelley et a1. Jan. 31, 1961 FOREIGN PATENTS 664,484 Great Britain J an. 9, 1952 783,658 Great Britain Sept. 25, 1957 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,155,624 November 3, 1964 I William A. Kelly It is hereby certified that error appears in the above numbered pat-- ent requiring correction and that the said Letters Patent should read as corrected below line 39, strike out "amount up to about 10%" Column 2,
to about 1% and insert instead about 0.2%
Signed and sealed this 16th day of March 1965.
(SEAL) Attes t':
ENEST W; SWIDER EDWARD J. BRENNER Commissioner of Patents