Chapter IV: Classification of Soaps (1)

In considering the many different varieties of soaps, their classification is purely an arbitrary one. No definite plan can be outlined for any particular brand to be manufactured nor can any very sharp distinction be drawn between the many soaps of different properties which are designated by various names. It is really a question to what use a soap is to be put, and at what price it may be sold. There is, of course, a difference in the appearance, form and color, and then there are soaps of special kinds, such as floating soaps, transparent soaps, liquid soaps, etc., yet in the ultimate sense they are closely allied, because they are all the same chemical compound, varying only in their being a potash or soda soap, and in the fatty acids which enter into combination with these alkalis. Thus we can take a combination of tallow and cocoanut oil and make a great many presumably different soaps by combining these substances with caustic soda, by different methods of manufacture and by incorporating various other ingredients, as air, to form a floating soap, alcohol to make a transparent soap, dyestuffs to give a different color, etc., but essentially it is the same definite compound.

The manufacturer can best judge the brand of soaps he desires to manufacture, and much of his success depends upon the name, package, shape, color or perfume of a cake of soap. It is the consumer whom he must please and many of the large selling brands upon the market today owe their success to the above mentioned details. The great majority of consumers of soap know very little concerning soap, except the fact that it washes or has a pleasant odor or looks pretty, and the manufacturer of soap must study these phases of the subject even more carefully than the making of the soap itself.

For a matter of convenience we will classify soap under three general divisions:

I. Laundry soaps, including chip soaps, soap powders and scouring soaps.

II. Toilet soaps, including floating soap, castile soap, liquid soap, shaving soap, etc.

III. Textile soaps.

LAUNDRY SOAP.

The most popular household soap is laundry soap. A tremendous amount of this soap is consumed each day in this country, and it is by far manufactured in larger quantities than any other soap. It is also a soap which must be sold cheaper than any other soap that enters the home.

The consumers of laundry soap have been educated to use a full boiled settled rosin soap and to make a good article at a price this method should be carried out, as it is the one most advisable to use. The composition of the fats entering into the soap depends upon the market price of these, and it is not advisable to keep to one formula in the manufacture of laundry soap, but rather to adjust the various fatty ingredients to obtain the desired results with the cheapest material that can be purchased. It is impossible to use a good grade of fats and make a profit upon laundry soap at the price at which it must be retailed. The manufacturer of this grade of soap must look to the by-product, glycerine, for his profit and he is fortunate indeed if he realizes the entire benefit of this and still produces a superior piece of laundry soap.

SEMI-BOILED LAUNDRY SOAPS.

It is advantageous at times to make a laundry soap by a method other than the full boiled settled soap procedure as previously outlined. This is especially the condition in making a naphtha soap, in which is incorporated naphtha, which is very volatile and some of the well known manufacturers of this class of soap have adopted this process entirely. A laundry soap containing rosin cannot be advantageously made by the cold process, as the soap thus made grains during saponification and drops a portion of the lye and filling materials. By making a semi-boiled soap this objection is overcome. The half boiled process differs from the cold process by uniting the fats and alkalis at a higher temperature.

To carry out this process the following formulae have been found by experience to give satisfactory results.

I. lbs.

Tallow 100
Rosin 60
Soda Lye, 36deg. B. 80

II.

Tallow 100
Rosin 60
Silicate of Soda 25
Soda Lye, 36deg. B. 85

III.

Tallow 100
Rosin 100
Lye, 36deg. B. 105
Silicate of Soda 25
Sal Soda Solution 20

In any of these formulas the sodium silicate (40deg. B.) may be increased to the same proportion as the fats used. By so doing, however, twenty pounds of 36deg. B. lye must be added for every hundred pounds of silicate additional to that indicated or in other words, for every pound of silicate added 20 per cent. by weight of 36deg. B. lye must be put into the mixture. The rosin may also be replaced by a previously made rosin soap.

To make a semi-boiled soap, using any of the above formulae, first melt the rosin with all or part of the fat, as rosin when melted alone readily decomposes. When the mixture is at 150deg. F. run it into the crutcher and add the lye. Turn on sufficient dry steam to keep the temperature of the soap at about 150deg. F. in the winter or 130deg. F. in summer. After the mass has been mixed for half an hour, by continuously crutching the soap it will at first thicken, then grain and it may again become thick before it becomes smooth. When the mass is perfectly smooth and homogeneous drop into a frame and crutch in the frame by hand to prevent streaking. After standing the required length of time the soap is finished into cakes as usual.

SETTLED ROSIN SOAP.

Settled rosin soaps are made from tallow, grease, cottonseed oil, bleached palm oils of the lower grades, corn oil, soya bean oil, arachis oil, distilled garbage grease, cottonseed foots or fatty acids together with an addition of rosin, varying from 24 per cent. to 60 per cent. of the fatty acids which should titer from 28 to 35. A titer lower than 28 will prevent the finished kettle of soap from being capable of later taking up the filling materials. As has already been stated under hardened oils, these being very much higher in titer allow a greater percentage of rosin to be added. Thus hardened fish oils and cottonseed oil are gradually being more extensively employed in soaps of this character.

The procedure of handling the kettle is similar to that given under full boiled soap. The stock is steamed out into a settling tank and allowed to settle over night, after which it is pumped into the soap kettle. Having stocked the kettle, open steam is turned on and 10deg.-12deg. B. lye is run in, while using a steam pressure of ninety to one hundred pounds in order to prevent too great a quantity of condensation of the steam, the water thus being formed weakening the lye. If a steam pressure of fifty to sixty pounds is available, a stronger lye (20deg. B.) should be added. Care must be taken not to allow the lye to flow in too rapidly or the soap will not grain. The saponification is only attained by prolonged boiling with sufficient lye of proper strength. When saponification has taken place, the mass begins to clear and a sample taken out with a paddle and cooled should show a slight pink with a 1 per cent. alcoholic phenolphthalein solution.

It may be stated here that in using this indicator or any other to test the alkalinity of soap, the soap should always be cooled and firm, as whenever water is present, the dissociation of the soap thereby will always react alkaline. When this state is reached the mass is ready for graining, which is accomplished by distributing salt brine or pickle or spreading dry salt over the surface of the soap. The kettle is then thoroughly boiled until the mass shows a soft curd and the lye drops clearly from a sample taken out with a trowel or paddle. The steam is then shut off and the soap allowed to settle over night. The lyes are then run off to the spent lye tank for glycerine recovery. In saponifying a freshly stocked kettle it is apt to bunch. To prevent this salt is added at various times to approximately one per cent. of the fat used.

If, by any possibility the soap has bunched, this condition may be remedied by the addition of more strong lye and boiling until it is taken up. To work a kettle to its full capacity it is advisable to make two "killing" changes. First add about 75 per cent. of the fat and grain as directed. Run off the spent lyes and then add the remainder of the stock and repeat the process. When the spent lye has been run to storage, the open steam is again turned on and 18deg. B. lye gradually allowed to run in. The rosin is now broken up and put into the kettle, or a previously made rosin soap is pumped in.

Lye is then added until the soap has a sharp taste after about three hours of continuous boiling, or when the soap is in the closed state. More lye should then be run into the kettle to grain the soap well, the grain not being too small. Then allow the soap to settle over night and draw off the strengthening lye. The next day again boil up the kettle and add water until the soap thins out and rises or swells high in the kettle. A sample taken out at this stage upon a hot trowel should run off in large flakes. The surface of the soap should be bright and shiny.

If the sample clings to the trowel, a slight addition of lye will remedy this defect. The kettle is then allowed to rest, to drop the nigre and to cool for some time, depending upon the size of the kettle. The proper temperature is such that after having been pumped to the crutcher and the filling materials having been added, a thermometer placed into the mass should indicate 128deg.-135deg. F. after the crutcher has run from ten to fifteen minutes. The filling material may consist of from 7-9 per cent. of sal soda solution, 36deg.-37deg. B. warm or just enough to close up the soap and make it rise high in the center of a screw crutcher and make it cling close to a warm trowel. Other fillers such as outlined below are added at this point.

An addition of from 2-3 per cent. of a special mineral oil for this purpose will impart a finish to the soap and 3-5 per cent. starch added prevents the soap from cracking in the frames. Other filling material as silicate of soda, borax, talc or silex are used. After the filling material has been thoroughly crutched through the soap it is framed, and, after being several days in the frame to solidify and cool the soap is ready for slabbing, pressing and wrapping.

In order to more definitely illustrate the composition of the mixture of fats and oils entering into the formation of a laundry soap a typical formula may be given for such a soap containing 40 per cent. rosin added to the amount of fats used:

lbs.
Grease 7,000
Tallow 4,000
Corn Oil 7,000
Cottonseed Oil 3,000
Rosin 8,400

The following have been found to be satisfactory filling materials and are calculated upon the basis of a 1,400-pound frame of soap.

I. lbs.

Sodium Silicate, 38deg.-40deg. B. 100
Mineral Oil 25
Sal Soda Solution, 36deg. B. 80
Borax 1

II.

Sal Soda Solution, 36deg. B. 80
Mineral Oil 25
Sodium Silicate 60

III.
Soda Ash 10
Sal Soda 55
Sodium Silicate 115
Mineral Oil 40
Brine (Saturated Solution) 10
Sodium Silicate, 38deg.-40deg. B. 100

IV.
Sodium Silicate 100
Silex or Talc 200
Soda Ash 50

V.

Sal Soda Solution, 36deg. B. 90
Sodium Silicate 50-60
Mineral Oil 25
Borax Solution, 25deg. B. (hot) 15

CHIP SOAP.

Chip soap is used extensively in laundries but is also used largely in other branches. It may be made either as a settled soap or by the cold made process.

To make a full boiled settled chip soap, proceed as directed under settled laundry soap. The kettle is stocked with light grease or a mixture of grease with corn oil or other cheap oils. For this kind of soap the rosin is eliminated.

Chip soap may be filled as well as laundry soap. This is done in the crutcher and the following adulterations are suitable.

lbs.
Settled Soap 700
Soda Ash 35
Sodium Silicate 215
or
Settled Soap 700
Silicate of Soda 560
Soda Ash 18
Carbonate of Potash, 26deg. B. 50

The cheapest method of drying is by running this soap through a drying machine and this is the procedure usually carried out for making dried chip soap.

COLD MADE CHIP SOAPS.

To make chip soaps by the cold process a sweet tallow of low percentage of free fatty acid should be employed. The tallow is heated to 120deg. to 135deg. F. and the lye run in slowly at first and then the silicate of soda is added. The mass is then mixed until a finger drawn through the soap leaves a slight impression, then dropped into frames or barrels. Soaps containing a small percentage of fat should be well covered in the frame for twenty-four hours to retain their heat and insure proper saponification. The following formulae are suitable:

I. lbs.
Tallow 1,200
Soda Lye, 35deg. B. 850
Sodium Silicate 750

II.
Tallow 475
Ceylon Cocoanut Oil 100
Soda Lye, 37deg. B. 325
Potash Lye, 37deg. B. 56

III.
Tallow 500
Soda Lye, 37-1/2deg. B. 297
Sodium Silicate 416
Potash Lye, 37-1/2deg. B. 37-1/2

IV.
Tallow 450
Soda Lye, 37-1/2deg. B. 255
Sodium Silicate 450
Potash Lye, 37-1/2deg. B. 50

V.
Tallow 450
Soda Lye, 35deg. B. 470
Sodium Silicate 650

VI.
Tallow 420
Sodium Silicate 600
Soda Lye, 37-12deg. B. 270

UNFILLED CHIP SOAP.

A very good grade of chip soap is made by employing no filling material whatsoever, but unfortunately the price of this soap has been cut to such an extent that these can not compete with a filled chip. A number of the best soaps of this kind are made from a settled soap using a light grease with corn oil. A soap of this nature is made as follows.

lbs.
Settled Soap 800
Sal Soda Solution, 36deg.-37deg. B. 252
Soda Ash 182

If this soap is run into frames it may be stripped and chipped in two days.

SOAP POWDERS.

Soap powders have become so great a convenience as a general cleansing agent that to eliminate them from the household necessities would mean much unnecessary energy and work to the great number of consumers of this product. They may be manufactured so cheaply and still be efficient, that their use has almost become universal for cleansing and scouring purposes. The uses to which soap and scouring powders are adapted are too well known to enter into a description of their employment. Since they offer a greater profit to the manufacturer than ordinary household soap, many brands are extensively advertised.

Numerous combinations for soap powders might be cited and it is a simple matter to vary the ingredients as to fat content and manufacture a powder of this sort as low as a cent a pound. Many substances are incorporated with soap, such as salt, soda ash, tripoli, crushed volcanic deposits, ground feldspar, infusorial earth of various kinds, silex, etc. In addition to these various fillers, compounds with true cleansing and bleaching properties, in addition to soap, are added, such as the salts of ammonium (sal ammoniac, carbonate of ammonia), sodium perborate and the peroxides of various metals. The public, however, have been accustomed to receive a large package of soap or scouring powder for a small amount of money and it is a difficult matter for the manufacturer to add more expensive substances of this nature to his product, to increase its efficiency, without raising the price or decreasing the size of the package.

In manufacturing soap powders, the dried soap chips might be mixed with the filler and alkali and then pulverized. This method is not extensively employed nevertheless. The process which is the most economical is one whereby the ingredients are mixed in a specially adapted mixer for heavy material until dry and then run directly to the crusher and pulverizer, after which it is automatically packed, sealed and boxed. Another method of procedure is to run out the mixture from the crutcher to the frames, which are stripped before the soap cools, and is cut up at once, for if it hardens it could not be cut with wires. It is better, however, to run the mixture into sheets upon a specially constructed floor and break up the mass when cool.

Formulae for soap powders which have been found to be suitable for running dry in the mixer follow:

I
Soda ash, 58 per cent. 42 lbs.
Silica 220 "
Settled soap (usually cottonseed). 25 "
Salt 10 "

II
Soap (settled cottonseed) 40 lbs.
Soda ash, 58 per cent. 60 "

III
Settled soap 100 lbs.
Soda ash, 58 per cent. 400 "

Fillers in varying proportions may replace the soda ash in the above formulae. It is of course understood that the soap has been previously made and run as molten soap into the crutcher.

The following soap powders will not dry up in the crutcher upon running, but are of the class which may be framed or run on the floor to solidify:

I
Soap 850 lbs.
Filler 400 "
Sal soda solution, 20 degs. B 170 "

II
Soap 650 lbs.
Filler 550 "
Sal soda solution, 20 degs. B. 340 "

III
Soap 80 lbs.
Filler 550 "
Sal soda solution 170 "

IV
Soap (settled tallow) 800 lbs.
Filler 400 "
Sal soda solution 170 "
Water 100 "

V

First saponify 100 parts house grease and 100 parts ordinary grease and make a run soap. Then use in crutcher either:

Soap 400 lbs.
Filler 575 "
Hot water 60 "
or
Soap 200 lbs.
Hot water 200 "
Filler 625 "

It would be a simple matter to write numerous additional formulae, but the above are typical. The manufacturer must judge for himself just what filling material to use. The filler indicated in the above formulae is therefore left open. A few formulae for more expensive powders than those given recently appeared among others in the "Seifensieder Zeitung"[9]:

I

Powdered soap 90 lbs.
Sodium perborate 10 "

The perborate should be added when the powder is perfectly dry or it loses its bleaching properties.

II

Soap powder, 20 per cent. fat.
Cocoanut oil fatty acids 25 lbs.
Olein 25 "
Bone fat 70 "
Soda lye, 30 degs. B. 90 "
Water 150 "
Ammonium carbonate 125 "

III

Soap powder, 10 per cent. fat.
Cocoanut oil fatty acids 20 lbs.
Olein 10 "
Bone fat 20 "
Soda lye, 30 degs. B. 30 "
Water 175 "
Ammonium carbonate 175 "

LIGHT OR FLUFFY POWDERS.

Light or fluffy powders containing 35-45% moisture can be made in two ways. The first method requiring a minimum equipment is to mix the powder and sal soda in a mixer, allow it to stand in frames for a week to crystallize or spread it on the floor for a few hours to dry and then grinding it.

The continuous method finishes the powder in a few minutes and with a minimum amount of labor. By this process the various ingredients, soap, soda ash solution, etc., are measured, run by gravity into the mixer, mixed and the molten mass run over the crystallizer or chilling rolls thru which either cold water or brine is pumped. From the roll the powder is scraped off clean by a knife, passes to a screen which sends the tailings to a grinder, falls into a storage bin from whence it is weighed and packed by an automatic weighing machine into cartons made up in most cases by another machine. Due to the large percentage of moisture contained in these soap powders the carton is generally wrapped in wax paper to aid in the prevention of the escape of moisture.

SCOURING POWDERS.

Scouring powders are very similar to soap powders and differ only in the filler used. We have already considered these fillers under scouring soap, from which they do not differ materially. They are usually insoluble in water to aid in scouring. The mixer used for substances of this kind in incorporating the soap and alkali must be of strong construction.

SCOURING SOAP.

Scouring soaps resemble soap powders very closely in their composition, in that they are a combination of soap and filling material. Since more lather is required from a scouring soap than in soap powders, a cocoanut oil soap is generally used. The usual filling material used is silex. The greatest difficulty in the manufacture of scouring soap is the cracking of the finished cake. This is usually due to the incorporation of too great an amount of filler, or too high a percentage of moisture.

In manufacturing these soaps the cocoanut oil is saponified in the crutcher with 38 degs. B. lye, or previously saponified as a run soap, as already described under "Marine Soaps." To twenty-five parts of soap are added a percentage of 38 degs. B. sal soda or soda ash solution, together with a small quantity of salt brine. To this mixture in the crutcher seventy-five parts of silex are then added, and a sufficient amount of hot water to make the mass flow readily. Care must be exercised to not add too great a quantity of water or the mass will crack when it cools. The mass is then framed and cut before it sets, or poured into molds and allowed to set. While silex is the most extensively used filler for scouring soaps, it is feasible to incorporate other substances of like character, although it is to be remembered that the consumer is accustomed to a white cake, such as silex produces. Any other material used to replace silex should also be as fine as this product.

FLOATING SOAP.

Floating soap occupies a position midway between laundry and toilet soap. Since it is not highly perfumed and a large piece of soap may be purchased for small cost, as is the case with laundry soap, it is readily adaptable to general household use. Floating soap differs from ordinary soap in having air crutched into it which causes the soap to float in water. This is often advantageous, especially as a bath soap, and undoubtedly the largest selling brand of soap on the American market today is a floating soap.

In the manufacture of floating soap a high proportion of cocoanut oil is necessary. A most suitable composition is one part cocoanut oil to one part of tallow. This is an expensive stock for the highest grade of soap and is usually cheapened by the use of cottonseed or various other liquid oils. Thus it is possible to obtain a floating soap from a kettle stocked with 30 per cent. cocoanut oil, 15 per cent. cottonseed oil and 55 per cent. tallow. With this quality of soap, however, there is a possibility of sweating and rancidity, and of the soap being too soft and being poor in color.

The process of manufacture is to boil the soap in an ordinary soap kettle, after which air is worked into the hot soap by a specially constructed crutcher, after which the soap is framed, slabbed, cut into cakes and pressed.

Concerning the boiling of the soap, the saponification must be carefully carried out, as the high proportion of cocoanut oil may cause a violent reaction in the kettle causing it to boil over.

The method of procedure is the same as for a settled soap up to the finishing. When the mass is finally settled after the finish, the soap should be more on the "open" side, and the object should be to get as long a piece of goods as possible.

Due to its high melting point, a much harder crust forms on the surface of a floating soap and in a greater proportion than on a settled soap during the settling. In a large kettle, in fact, it has been found impossible to break through this crust by the ordinary procedure to admit the skimmer pipe. Much of the success of the subsequent operations depends upon the completeness of the settling, and in order to overcome the difficulties occasioned by the formation of the crust everything possible should be done in the way of covering the kettle completely to enable this period of settling to continue as long as possible.

When the soap is finished it is run into a specially constructed U-shape crutcher, a Strunz crutcher is best adapted to this purpose, although a rapidly revolving upright screw crutcher has been found to give satisfaction upon a smaller scale, and a sufficient quantity of air beaten into the soap to make it light enough to float. Care must be taken not to run the crutcher too rapidly or the soap will be entirely too fobby. During this operation the mass of soap increases in bulk, and after it has been established how much air must be put into the soap to satisfy the requirements, this increase in bulk is a criterion to estimate when this process is completed.

It is of course understood that the longer the crutching continues the greater quantity of air is incorporated and the increase of volume must be established for a particular composition by sampling, cooling the sample rapidly and seeing if it floats in water. If the beating is continued too long an interval of time, the finished soap is too spongy and useless.

The temperature of the mass during crutching is most important. This must never exceed 158 degrees F. At 159 degrees F. the operation is not very successful, yet the thermometer may indicate 140 degrees F. without interfering with this operation. If, however, the temperature drops too low, trouble is liable to be met with, by the soap solidifying too quickly in the frames.

When the crutching is completed, the soap is allowed to drop into frames through the valve at the bottom of the crutcher and rapidly crutched by the hand in the frames to prevent large air spaces and then allowed to cool. It is an improvement to jolt the frames as they are drawn away as this tends to make the larger air bubbles float to the surface and thus reduce the quantity of waste. When the soap has cooled, the frame is stripped and the soap slabbed as usual. At this point a layer of considerable depth of spongy soap will be found to have formed. This of course must be cut away and returned to the kettle. The last few slabs are also often rejected, inasmuch as the weight of the soap above them has forced out so much of the air that the soap no longer floats. As a fair average it may be estimated that not more than 50 to 60 per cent. of the soap in the kettle will come out as finished cakes. the remaining 40 to 50 per cent. being constituted by the heavy crust in the kettle, the spongy tops, the bottom slabs and scrapings. This soap is of course reboiled and consequently not lost, but the actual cakes obtained are produced at a cost of practically double labor.

It is advisable to add a small quantity of soap blue color to the mass while crutching to neutralize the yellowish tint a floating soap is liable to have.

Some manufacturers add a percentage of carbonate of soda, about 3 per cent., to prevent the soap from shrinking. Floating soap may also be loaded with sodium silicate to the extent of about 5 per cent.

TOILET SOAP.

It is not a simple matter to differentiate between toilet soaps and various other soaps, because numerous soaps are adaptable to toilet purposes. While some soaps of this variety are manufactured by the cold made or semi-boiled process, and not milled, the consumer has become accustomed to a milled soap for general toilet use.

The toilet base most extensively employed is a tallow and cocoanut base made as a full boiled settled soap. The manufacture of this base has already been outlined and really needs no further comment except that it is to be remembered that a suitable toilet soap should contain no great excess of free alkali which is injurious to the skin. Cochin cocoanut oil is preferable to the Ceylon cocoanut oil or palm kernel oil, to use in conjunction with the tallow, which should be a good grade and color if a white piece of goods is desired. The percentage of cocoanut oil may be anywhere from 10 to 25 per cent., depending upon the kind of lather required, it being remembered that cocoanut oil increases the lathering power of the soap.

In addition to a tallow base, numerous other oils are used in the manufacture of toilet soaps, especially palm oil, palm kernel oil, olive oil and olive oil foots, and to a much less extent arachis or peanut oil, sesame oil and poppy seed oil, oils of the class of cottonseed, corn and soya bean oils are not adapted to manufacturing a milled soap, as they form yellow spots in a finished cake of soap which has been kept a short time.

Palm oil, especially the Lagos oil, is much used in making a palm base. As has already been stated, the oil is bleached before saponification. A palm base has a yellowish color, a sweetish odor, and a small quantity added to a tallow base naturally aids the perfume. It is especially good for a violet soap. The peculiarity of a palm oil base is that this oil makes a short soap. By the addition of some tallow or twenty to twenty-five per cent. of cocoanut oil, or both, this objection is overcome. It is a good plan in using a straight palm base to add a proportion of yellow color to hold the yellowish tint of this soap, as a soap made from this oil continues bleaching upon exposure to air and light.

Olive oil and olive oil foots are used most extensively in the manufacture of castile soaps. The peculiarity of an olive oil soap is that it makes a very slimy lather, and like palm oil gives the soap a characteristic odor. An olive oil soap is usually considered to be a very neutral soap and may readily be superfatted. Much olive oil soap is used in bars or slabs as an unmilled soap and it is often made by the cold process. Peanut oil or sesame and poppy seed oil often replaces olive oil, as they form a similar soap to olive oil.

In the manufacture of a toilet soap it is hardly practical to lay down a definite plan for the various bases to be made. From the combination of tallow, palm oil, cocoanut oil, palm kernel oil, olive oil and olive oil foots, a great many bases of different proportions might be given. The simplest method is to make a tallow base, a palm base and an olive oil base. Then from these it is an easy matter to weigh out any proportion of these soap bases and obtain the proper mixture in the mill. If, however, as is often the case, a large quantity of soap base of certain proportions of these, four or even more of these fats and oils is required, it is not only more economical to stock the kettle with the correct proportion of these oils, but a more thorough mixture is thus obtained by saponifying these in the kettle. In view of the fact that it is really a question for the manufacturer to decide for himself what combination of oils he desires for a particular soap we will simply outline a few typical toilet soap bases in their simplest combination. It is understood that these soaps are suitable for milled soaps and are to be made as fully boiled settled soaps. Palm kernel oil may be substituted for cocoanut oil in all cases.

TALLOW BASE.

Tallow 75-90 parts
Cocoanut oil 25-10 parts

PALM BASE.

Bleached Lagos palm oil 75-80 parts
Cocoanut oil 25-20 parts

or

Tallow 30 parts
Palm oil 60 parts
Cocoanut oil 10 parts

OLIVE OIL BASE (WHITE).

Olive oil 75-90 parts
Cocoanut oil 25-10 parts

or

Olive oil 40 parts
Tallow 40 parts
Cocoanut 20 parts

Where a green olive oil base is desired, olive oil foots are substituted for the olive oil. Peanut oil may replace the olive oil or part of it, the same being true of sesame oil and poppy seed oil.

PALM AND OLIVE BASE.

Palm oil 50 parts
Olive oil 30 parts
Cocoanut oil 20 parts

or

Palm oil 20 parts
Olive oil 10 parts
Tallow 50 parts
Cocoanut oil 20 parts

CHEAPER TOILET SOAPS.

It is often necessary to manufacture a cheaper grade of soap for toilet purposes to meet the demand of a certain class of trade as well as for export. To accomplish this it is of course necessary to produce a very inferior product and run down the percentage of fatty acids contained in the soaps by the addition of fillers or to use cheaper oils in manufacturing. The most simple method of filling a soap is to load it at the mill with some substance much less expensive than the soap itself. Many of the cheaper toilet soaps, however, are not milled and it is, therefore, necessary to follow out some other procedure.

Milled soaps, as has just been stated, are loaded at the mill. The consumers of cheaper toilet soaps in this country are accustomed to a milled soap and this grade of soap for home consumption is very often filled with numerous substances, but most generally by adding starch and talc. The addition of such materials of course later exhibit themselves by imparting to the cake of soap a dead appearance. Talc is more readily detected in the soap than starch by washing with it, as talc is insoluble and imparts a roughness to the soap, like sand or pumice, as the soap wears down. It may readily be added to 20 per cent. by weight. Starch is to be preferred to talc, in loading a soap, as it is not so readily noticeable in washing. It leaves the cake itself absolutely smooth although the lather formed is more shiny. This substance may be employed to as high a percentage as one-third the weight of the soap. It is, of course, possible to cheapen the best soap base by this method and the price may be further lowered by using the less expensive oils and fats to make the soap base.

RUN AND GLUED UP SOAPS.

A very cheap grade of soap may be made by making a run soap and adding the filler e. g. sodium silicate in the kettle during saponification. The percentage of fatty acids may be brought down to 10 per cent., although of course a soap of this type shrinks a whole lot upon exposure.

In making a "glued up" soap the procedure is the same for making the soap itself as with a settled soap, except that the soap is finished "curd" and later filled in the crutcher. The percentage of fatty acids in a soap of this type is seldom below 50 per cent.

The method of "gluing up" a soap is best illustrated by a typical soap of this character in which the kettle is charged with the following stock.

Bleached palm oil 5 parts
Distilled grease 2 "
Cotton oil foots stock, 63% fatty acid 1 "
Rosin 4 "

The palm oil is first run into the kettle, saponified and washed to extract any glycerine, then the rest of the fats and finally the rosin. The soap is then finished and settled as with a boiled settled soap. To assure success it is absolutely necessary that the soap settle as long a period as possible, or until the temperature is about 150 degs. F. The ideal temperature for carrying out the "gluing up" process is 140 degs. F., as at a lower temperature than this the soap is liable to cool too quickly and not be thoroughly glued up. A higher temperature than 150 degs. F. causes delay in that the soap does not properly take the filler at a higher temperature and the soap must be kept in the crutcher until the temperature drops to the right point.

The soap is run into the crutcher and the percentage of fatty acids run down to 50-55 per cent. with one of the following mixtures:

Sodium silicate, 59-1/2deg. B. 1 part
Potassium carbonate, 51deg. B. 1 "

or

Sodium silicate, 59-1/2deg. B. 1 part
Potassium carbonate, 51deg. B. 1 "
Sodium sulfate, 28deg. B. 1 "

From 230 to 300 pounds of either of these mixtures are required for a crutcher holding 2,600 pounds of soap.

The crutching is continued until the mass is well "spiked," that is to say, a freshly broken surface of the soap, as the crutcher blade is jerked away, stands up like shattered sheets in triangular form [Transcriber's note: three triangles]), which retain their shape perfectly. When this condition is realized the soap is run into frames which are carefully crutched by hand to remove any air spaces. The surface of the soap is then smoothed down and heaped up in the center. After standing a day to contract, the surface is again leveled and a snugly-fitting board placed on the top of the soap upon which a weight is placed or upon which the workman treads and stamps until the surface is flat, thus assuring the further removal of air spaces. The soap remains in the frame from six to eight days and is then slabbed, barred and pressed by the usual method employed for soaps thus handled without milling.

In a soap of this nature no hard and fast rule can be laid down as to the quantity of solution to be used for "gluing up" or the strength of the solution. In a soap of the type described the most satisfactory appearing cake will be obtained from a soap containing 58 per cent. fatty acids. That is to say, about 8 per cent. to 10 per cent. filling solution is added per hundred pounds of soap. The filling solutions given are very satisfactory. Carbonate of soda should be avoided in connection with sodium silicate as the property of efflorescing on the surface of the finished cake after a short time will prove detrimental. To assure successful gluing up it is advisable to experiment upon a small scale to determine the exact extent to which the filling solution should be diluted. Various proportions of water are added to a certain quantity of the filled soap. After the soap has been filled in a small receptacle a sample is taken and rubbed between the fingers. If the freshly exposed surface is smooth and glossy, the filling solution is weak enough, if rough it is too strong. It is of course understood that the temperature must be correct, 140 degs. to 150 degs. F., or the soap will be rough. By this means the operator can readily judge the correct strength of his filling solution. When properly carried out a perfectly satisfactory soap is obtained.

CURD SOAP.

The object of a soap which is finished "curd" or grained, is to obtain a harder piece of goods from low titer fat or to increase the percentage of fatty acids in the finished soap. This is still another method of producing a cheap grade of soap as by its adoption the cheaper oils and fats may be used to obtain a firm piece of soap.

A typical charge for curd soap is:

Red oil 63 parts
Tallow 10 "
Rosin 27 "

Cotton seed foots may be employed in place of red oil and a tallow of too high titer is not suitable for this kind of soap.

The red oil and tallow are first saponified with 15 degs. B. lye, boiler pressure 80-90 pounds, 18 degs. B. lye for lower steam pressure, and two washings given to extract the glycerine. The rosin is added at the strengthening change and at the finish the soap is "pitched," that is to say, the soap is settled over night only. The next day the lyes are drawn off and a portion of the nigre pumped to another kettle which prevents later streaking of the soap. The soap is then boiled with 18 degs. B. lye as with another strengthening change under closed steam. Salt brine or "pickle," 15 degs. B. is then added and the mass boiled with closed steam until the brine reaches a density of 18 degs. B. and the kettle pumped the next day. A soap of this type requires either hand or power crutching to assure homogeneity and prevention of streaks. To obviate any air spaces it is advisable to place over the top of the frame a tightly-fitted board which is heavily weighted down. This soap is also pressed without any milling.

COLD MADE TOILET SOAPS.

Comparatively little toilet soap is made by the cold or semi-boiled processes. While these are the simplest methods of manufacturing soaps the drawbacks of using them are numerous and only in a few cases are they very extensively employed. To make a toilet soap by the cold process a combination of good grade tallow and cocoanut oil is required. It requires 50 per cent. by weight of 36 degs. B. lye to saponify a given weight of tallow and 50 per cent. of 38 degs. B. lye for cocoanut oil. The lyes are used full strength or may be reduced slightly with water and the method of procedure is the same as already given in the general directions for cold made soaps.

Cold made soaps are readily filled with sodium silicate which is added at the same time the stock is put into the crutcher. In adding the silicate it is necessary to add additional lye to that required for saponifying the fats, about 20 per cent. of 36 degs. B. lye is the proper amount. There is of course a certain amount of shrinking due to the addition of this filler and the finished cake is exceedingly hard, yet the author has seen a good looking cake of cheap soap made from as high a proportion as 420 parts of tallow to 600 parts of silicate.

Cold made soaps are usually pressed without milling, although it is readily feasible to mill a cold made soap provided it is not a filled soap such as has just been described.

PERFUMING AND COLORING TOILET SOAPS.

Equally important as the soap itself or even to a greater extent is the perfume of a toilet soap. A prominent manufacturer recently made the statement, which is often the truth, that it makes no difference to the public what kind of soap you give them, as long as you put plenty of odor into it. The perfuming of soaps is an art in itself and a subject to be treated by one versed in this particular branch. We can only take into account the importance of the perfume as related to toilet soap not only, but the necessity of adding a certain proportion of the cheaper products of odoriferous nature to laundry soap to cover and disguise the odor of even this type of soap.

The price of a cake of toilet soap to a great extent depends upon the perfume, and the manufacturer should aim to give the best possible perfume for a certain price. He should not allow his personal likes or dislikes to enter into the judgment of whether an odor is good or not, but submit it to a number of persons to obtain the concensus of opinion. In giving or selling a piece of soap to the consumer, it is second nature for him to smell it, and in the great majority of cases his opinion is formed not from any quality the soap itself may have during use, but from the odor. This only emphasizes the fact that the perfume must be pleasing, not to one person, but to the majority, and many brands owe their popularity to nothing more than the enticing perfume.

Perfuming of soap is closely allied to the soap making industry, but as stated a branch in itself. It is, therefore, not our purpose to give numerous formulae of how to perfume a soap, but rather to advise to go for information to some one who thoroughly understands the characteristics of the numerous essential oils and synthetics and give positive information for the particular odor desired. Under no circumstances is it advisable to purchase a perfume already compounded, but since all perfumes are a blend of several or many essential oils and synthetics, it is a more positive assurance of obtaining what is desired, by purchasing the straight oils and blending or mixing them as one desires.

The perfume is added to a milled soap just before the milling process in the proper proportion per hundred pounds of soap. In cold made or unmilled soaps it is added in the crutcher while the soap is still hot. By this method, of course, a proportion of the perfume is lost due to its being more or less volatile.

COLORING SOAP.

While much toilet soap is white or natural in color, many soaps are also artificially colored. The soap colors used for this purpose are mostly aniline dyestuffs. The price of these dyestuffs is no criterion as to their quality, as the price is usually regulated by the addition of some inert, water soluble substance like common salt or sugar.

The main properties that a dyestuff suitable for producing a colored soap should have are fastness to light and to alkali. They should further be of such a type that the color does not come off and stain a wash cloth or the hands when the soap is used and should be soluble in water. Under no circumstances is it advisable to add these in such a quantity that the lather produced in the soap is colored. It is customary to first dissolve the dye in hot water as a standardized solution. This can then be measured out in a graduate and added to the soap the same time as the perfume is put in. About one part of color to fifty parts of water is the proper proportion to obtain a perfect solution, though this is by no means fixed. In making up a solution thus it is an improvement to add to the same about one-half of one per cent. of an alkali either as the hydroxide or carbonate. Then, if there is any possibility of change of color due to alkalinity of the soap, it will exhibit itself before the color is added.

A particularly difficult shade to obtain is a purple, as there is up to the present time no purplish aniline color known which is fast to light. Very good results in soap may be obtained by mixing a fast blue, as ultramarine or cobalt blue, with a red as rhodamine or eosine.

Inasmuch as the colors for soap have been carefully tested by most of the dyestuff manufacturers, and their information, usually reliable, is open to any one desiring to know about a color for soap, it is better to depend upon their experience with colors after having satisfied one's self that a color is what it is represented for a particular shade, than to experiment with the numerous colors one's self.

MEDICINAL SOAPS.

Soap is often used for the conveyance of various medicants, antiseptics or other material presumably beneficial for treatment of skin diseases. While soap is an ideal medium for the carrying of such materials, it is an unfortunate condition that when incorporated with the soap, all but a very few of the numerous substances thus employed lose their medicinal properties and effectiveness for curing skin disorders, as well as any antiseptic value the substance may have. Soap is of such a nature chemically that many of the substances used for skin troubles are either entirely decomposed or altered to such an extent so as to impair their therapeutic value. Thus many of the claims made for various medicated soaps fall flat, and really have no more antiseptic or therapeutic merit than ordinary soap which in itself has certain germicidal and cleaning value.

In medicating a soap the material used for this purpose is usually added at the mill. A tallow and cocoanut oil base is best adapted for a soap of this type. The public have been educated more or less to the use of colored soap to accentuate its medicinal value, and green is undoubtedly the most popular shade. This inference, however, is by no means true for all soaps of this character. Possibly the best method of arranging these soaps is briefly to outline some medicinal soaps.

SULPHUR SOAPS.

The best known sulphur soaps contain anywhere from one to 20 per cent. of flowers of sulphur. Other soaps contain either organic or inorganic sulphur compounds.

TAR SOAP.

The tar used in the manufacturing of tar soap is obtained by the destructive distillation of wood, the pine tar being the most extensively employed. While the different wood tars contain numerous aromatic compounds, such as phenols, phenyl oxides, terpenes and organic acids, these are present in such a slight proportion so as to render their effectiveness practically useless. It has, therefore, been tried to use these various compounds contained in the tar themselves to make tar soap really effective, yet tar is so cheap a substance that it is usually the substance used for medicating a tar soap. About 10 per cent. of tar is usually added to the soap with 2 ounces of lamp black per hundred pounds of soap.

SOAPS CONTAINING PHENOLS.

Phenol (Carbolic Acid) is most extensively used in soaps of this kind, which are called carbolic soaps. Carbolic soaps are generally colored green and contain from 1 to 5 per cent. phenol crystals.

The cresols are also extensively used for making soaps named carbolic. These substances impart more odor to the soap and really have more disinfecting powers than phenol when incorporated with soap.

Other soaps, containing the phenol group, which are well known are resorcinol soap, salol soap, thymol soap, naphthol soap, etc. From one to five per cent of the compound after which the soap is named is usually incorporated with the soap.

PEROXIDE SOAP.

Hydrogen peroxide in itself is an excellent disinfectant. It loses all its medicinal value, however, when added to the soap. To overcome this objection various metallic peroxides are added to the soap, as sodium peroxide, zinc peroxide and barium peroxide. These generate hydrogen peroxide by the addition of water. Sodium perborate is also used in peroxide soaps, as this substance is decomposed by water into hydrogen peroxide and sodium metaborate.

MERCURY SOAPS.

Mercuric chloride (corrosive sublimate) is most extensively used for the production of mercury soaps. Because of its extremely poisonous properties care should be taken in using it. Since it really eventually loses any antiseptic value in the soap through forming an insoluble mercury soap it might better be omitted entirely.

LESS IMPORTANT MEDICINAL SOAPS.

While the above mentioned soaps are probably the best known medicated soaps, there are numerous other soaps which may be classed under these kinds of soaps. Thus we have cold cream soap, which can be made by adding Russian Mineral Oil, 1 to 5 per cent., to the soap; witch hazel soap, made by the addition of extract of witch hazel; iodine soap, made by adding iodine or iodoform; formaldehyde soap, made by adding formaldehyde; tannin soaps, made by adding tannin. In fact, there have been incorporated in soap so great a number of substances that the list might be greatly enlarged.

Medicated soaps are not only used in solid form, but in powder, paste and liquid soap as well. The only difference in a soap like those just referred to is that the medicant is incorporated with these forms of soaps as convenience directs.

CASTILE SOAP.

A pure castile soap should be made from olive oil. This, however, is not always the case, as a number of oils as well as tallow are used to adulterate this oil to cheapen it, and there are even some soaps called castile which contain no olive oil at all. Most of the pure castile soap used in this country is imported, as it is a difficult matter for the American manufacturer to compete with the pure imported castile soap, since both labor and oil itself are so much cheaper in the vicinities of Europe where this oil is produced, that this advantage is more than compensated by the carrying and custom charges by importing the castile soap.