Soap-Making Manual Part 9

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 circ.u.mstances 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 a.s.surance 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 circ.u.mstances is it advisable to add these in such a quant.i.ty 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 cla.s.sed 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 quant.i.ty 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 a.s.sure 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