Chapter IV — Classification of Soaps (part 2 of 4)

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

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

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

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, 59-1/2° B.	1	part
Potassium carbonate, 51° B.	1	"

Sodium silicate, 59-1/2° B.	1	part
Potassium carbonate, 51° B.	1	"
Sodium sulfate, 28° 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 (Δ Δ Δ), 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.

Castile soap may be made either by the full boiled or cold process. There are numerous grades of olive oil, and those used for soap making are denatured to lower the duty charges. Olive oil makes a hard white soap, usually sold in bars, and olive oil foots a green soap, due to the coloring matter contained in this oil.

To make a boiled castile soap, a composition of 10 per cent. Cochin cocoanut oil and 90 per cent. olive oil may be used. To cheapen this, peanut oil (Arachis oil) may entirely replace the olive oil, or about 20 per cent. of corn or soya bean oil may be added. The oils are saponified as usual in making a settled soap and to prevent rancidity the soap is boiled near the finish for some time in the closed state with sufficient excess of alkali to give it a sharp taste, then grained with lye, the lye drawn off, closed with water and then grained with salt. This process is repeated until the desired strength is reached. The last graining should not be too great, and on the last change the soap should not be thinned out, as it will contain too great a quantity of water when slabbed.

In making a cold castile soap the usual method is pursued as already directed under cold made soap. When the soap is taken from the crutcher it is advisable, however, to keep the soap in the frame well covered to assure complete saponification. Some manufacturers use very small frames which are placed into compartments, well insulated to retain heat. Several formulae for cold made castile soaps, follow. It may be noted that some of these contain practically no olive oil.

I
Olive oil	2030
Palm kernel	674
Soda lye, 35 per cent. B.	1506
II
Olive oil	2030
Cochin cocoanut oil	674
Soda lye, 36 per cent. B.	1523
Sodium Silicate	82
III
Palm kernel oil	1578
Tallow	940
Olive oil	7
Sodium silicate, 20 per cent.	190
Soda lye, 36 per cent. B.	1507

IV
Olive oil (yellow)	1000
Soda lye, 37 per cent. B.	500
V
Olive oil	90
or
Palm kernel }	10
Cochin or cocoanut oil }	10
Lye, 37 per cent. B.	51

If any of the soaps containing a high proportion of cocoanut oil are boiled the soap will float. It is therefore necessary to keep the temperature as low as possible.