Chapter IV: Classification of Soaps (2)

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.

ESCHWEGER SOAP (BLUE MOTTLED).

Eschweger soap is a colored mottled or marbled soap made to a very slight extent in this country. Inasmuch as it has been introduced to the export trade, it is made for this purpose by some manufacturers. A high percentage of cocoanut oil is usually used together with tallow and grease. About one-third of each is a typical formula. In a soap of this character the fact that cocoanut oil soap takes up a large quantity of water and salts of various kinds and is difficult to salt out is made use of. The tallow and grease are first saponified as usual, then the cocoanut oil is pumped and saponified. When the saponification is nearly completed either silicate or carbonate of soda or common salt are added to make the soap "short" so as to form the mottle. The finishing of a soap of this type can only be gained by practice and it is rather difficult to explain the exact appearance of the kettle at this stage. The surface of the soap should be bright and lustrous with the steam escaping in numerous places in rose-like formation. A sample on the trowel should have a slight sharpness to the tongue and be plastic. When the soap slides from the trowel it should break short. When the soap has reached this stage the desired coloring matter, usually ultramarine, is added to the soap either in the kettle or crutcher and the soap framed. The yield is 200-215 pounds per hundred pounds of stock.

Several modifications of this general method for Eschweger soap are used by adopting the half boiled or cold process.

TRANSPARENT SOAP.

Transparent soap is really not a most desirable soap for toilet purposes, as it contains an excess of free alkali. It has, nevertheless, met with public approval because of the fact it is novel in being transparent. Except for this fact very little merit can be claimed for a soap of this kind.

The transparency of soap is generally due to the presence of alcohol, sugar or glycerine in the soap when it is made. It is very essential in a soap of this character, where lightness and clearness of color are desired, that the material for making the soap be carefully selected as to color and purity. The perfumes also play an important part in the color of the soap and many of the tinctures, balsams and infusions used in perfuming soap may eventually cause trouble by spotting. If the soap is artificially colored, which is almost always the case, the dyestuffs used for this purpose should have careful attention and only those should be used which are known to resist the action of alkalis. Where rosin is used this product must be of the better grade. Distilled water is always preferable for use in transparent soap. The government permits the use of a specially denatured alcohol. This alcohol is not taxed and consists of grain (ethyl) alcohol denatured with 5 per cent. wood (methyl) alcohol. Some soapmakers prefer to use a more expensive refined methyl alcohol, but outside of adding to the cost of the soap, there is no particular advantage. The glycerine should be chemically pure. As to the oils and fats these should be low in acid and of good color. Under no circumstances should the crutcher or kettle in which the soap is made be rusty or unclean in any way. For a light soap enameled utensils are to be preferred.

To obtain transparency in soap the following general methods may be given.

1. Where the transparency is due to sugar.

2. Where alcohol and glycerine produce transparency.

3. Where (1) or (2) is supplemented by the use of castor oil.

4. Where transparency depends upon the percentage of fatty acid in a soap and the number of times the soap is milled.

Under the first method at least 25 per cent. of the charge should be cocoanut oil, the other constituent being tallow or any fat or oil capable of giving a sufficiently hard soap. The soap is boiled and finished as usual, then run to the crutcher to be mixed with a strong cane sugar solution, containing 10-20 per cent. sugar of the weight of the soap. The sugar is dissolved in its own weight of water and the solution heated to 175 degs. F. before being very slowly added to the soap. As the water evaporates, soaps of this type show spots due to the sugar thus being thrown out of solution.

Transparent soap made under the second method may be saponified as usual and consist of any good toilet base. The soap is run to the crutcher and mixed with 95 per cent. alcohol in the proportion of one part alcohol to two parts of fatty acid contained in the soap together with glycerine in the same proportion.

By the third method castor oil alone may be used to make the soap or added to any of the above bases up to 33-1/3 per cent. of the charge. If castor oil only is used, but 2 per cent. or 3 per cent. of sugar is required.

In the last method a combination of 80 per cent. tallow, very low in free acid, 20 per cent. cocoanut oil and 5 per cent. W. W. rosin is a suitable charge. The saponification and finishing is carried out as with a full boiled soap. The soap is then placed into a jacketed vessel, provided with dry-steam coils, by which the excess water is evaporated from the soap until it contains 73 per cent. fatty acids. When the thick mass reaches this stage it is framed and when cool is suitable for obtaining a semi transparency which now depends upon the number of times the soap is milled, it being, of course, inferred that no solid matter of any sort be added to the soap.

COLD MADE TRANSPARENT SOAP.

While transparent soaps may be made by the above general methods they are usually made by the semi-boiled or cold process. By this process a more satisfactory soap is obtained and it is more simple to carry out. A detailed description of this method is best and most easily given by using a typical formula.

Charge:

Tallow 193-1/2 lbs.
Cochin Cocoanut Oil 169-1/2 "
Castor Oil 89-1/2 "
Soda Ash 7-3/4 "
Soda Lye, 36 degs. B. 256 "
Sugar (Cane) 198 "
Alcohol 126 "
Water (Distilled) 80 "

To proceed, first place into a crutcher or jacketed kettle the oils and fat and heat to 140 degs. F. Then add the soda ash dissolved in about 30 pounds of the water, after which the lye is added and the mass stirred until a finger or stick run over the surface leaves an imprint. Where the soap has reached this stage, it is well covered and allowed to stand about two hours or until it bulges in the center, after which the rest of the water which should contain no lime or other mineral substance and which is preferably distilled water, is added. The sugar is then slowly shoveled in while the mass is stirring and finally the alcohol is poured in. The heat is then increased to 160 degs. F. by dry steam and the soap crutched until dissolved. Under no circumstances should any soap be allowed to remain above the surface of the mass on the sides of the mixer. This crutching operation consumes about one hour, and when finished the soap should stand in the vessel about half an hour when a small sample is taken out to cool. This sample should be clear and show an excess of alkali. If it is not clear more alcohol is added, if not of sufficient strength more lye put in until the desired condition is reached. The perfume and color are now added.

The soap is then framed and allowed to set after which it is cut, allowed to dry slightly and then pressed. To obtain a polished cake transparent soaps are often planed before pressing and after pressing polished with a soft cloth, dampened with alcohol. Instead of framing this soap, it is sometimes "tubed," that is to say, the soap from the crutcher is run into specially constructed tubes of a shape near that of the desired cake and allowed to cool, after which it is cut and pressed. All scraps are returned to the crutcher, but in so doing the soap is slightly darkened in color. It is advisable to expose a finished cake of transparent soap to the air for some time as by so doing it becomes clearer.

Other formulae for cold made transparent soaps made as just outlined follow:

I.
Bleached Tallow 134 lbs.
Cochin Cocoanut Oil 88 "
Castor Oil 20 "
W. W. Rosin 7 "
Cane Sugar 64 "
Water 32 "
Glycerine 34 "
Soda Lye, 38 degs. B. 135 "
Alcohol 16 gal.

II.
Tallow 211 lbs.
Cochin Cocoanut Oil 185 "
Castor Oil 97-1/2 "
Soda Ash 8-1/2 "
Water 106 "
Soda Lye, 38 degs. B. 279 "
Sugar 216 "
Alcohol 137 "

III.
Castor Oil 60 lbs.
Cochin Cocoanut Oil 195 "
Tallow 120 "
Alcohol 115 "
Sugar 90 "
Water 53 "
Glycerine 53 "
Soda Lye, 38 degs. B. 205-1/2 "

IV.
Tallow 100 lbs.
Cochin Cocoanut Oil 100 "
Castor Oil 60 "
Glycerine 20 "
Rosin, W. W. 20 "
Sugar 40 "
Water 50 "
Soda Lye, 36 degs. B. 164 "
Alcohol 8 gal.

V.
Tallow 174 lbs.
Cocoanut Oil 114 "
Soda Lye, 38 degs. B. 170 "
Sugar 80 "
Water 72 "
Alcohol 16 gal.

Rosin may be added in this formula up to 20 per cent. of fats used and the tallow cut down correspondingly.

SHAVING SOAPS.

The requirements of a shaving soap are somewhat different than those of other soaps. To be a good shaving soap the lather produced therefrom must be heavy, creamy, but not gummy, and remain moist when formed on the face. The soap itself should be of a soft consistency so as to readily adhere to the face when used in stick form. It should furthermore be neutral or nearly so to prevent the alkali from smarting during shaving.

Shaving soap is made in the form of a stick, and a tablet for use in the shaving mug. Some shavers prefer to have the soap as a powder or cream, which are claimed to be more convenient methods of shaving. While a liquid shaving soap is not as well known because it has not yet become popular, some soap for shaving is made in this form.

Formerly shaving soap was extensively made from a charge of about 80 parts tallow and 20 parts cocoanut oil as a boiled settled soap, but either making the strengthening change with potash lye or using potash lye in saponifying the stock and graining with salt. Soaps for shaving made in this manner are very unsatisfactory, as they do not produce a sufficiently thick or lasting lather and discolor very materially upon ageing. Potassium stearate forms an ideal lather for shaving, but readily hardens and hence needs some of the softer oils, or glycerine incorporated with it to form a satisfactory soap for shaving.

The selection of materials for making a shaving soap is important. The tallow used should be white and of high titer. Cochin cocoanut oil is to be preferred to the other kinds, and the alkalis should be the best for technical use that can be purchased--76 per cent. caustic soda and 88-92 per cent. caustic potash are suitable. By the use of stearic acid it is a simple matter to reach the neutral point which can be carefully approximated.

The following are shaving soap formulae which have been found to give good satisfaction:

I. lbs.
Tallow 360
Stearic acid 40
Soda lye, 41deg. B. 147
Potash lye, 34deg. B. 87
Water 32
Gum tragacanth 1

II. lbs.
Tallow 282
Cocoanut oil 60
Stearic acid 50
Bayberry wax 18
Soda lye, 41deg. B. 147
Potash lye, 34deg. B. 90
Water 32

III. lbs.
Tallow 400
Cocoanut oil 176
Stearic acid 415
Caustic soda, 40deg. B. 182
Caustic potash, 38deg. B. 108

To proceed, first run into the crutcher the tallow, cocoanut oil and bayberry wax when used, and bring the temperature of the mass up to 140deg.-160deg. F. by dry steam. Then add the caustic soda lye and keep on heat with occasional mixing until it is all taken up. When this stage is reached gradually add all but about 5 per cent. of the potash lye, and complete the saponification. This point having been reached, the heat is turned off; the crutcher is run and the stearic acid, previously melted by dry steam in a lead-lined or enameled vessel, is run in in a continuous stream and the crutching continued for fifteen minutes to half an hour. Samples are taken at this time, cooled and tested by alcoholic phenolphthalein solution. If too alkaline more stearic acid is added, if too acid more potash lye from that previously reserved. After each addition of lye or stearic acid the mass is crutched from 10 to 15 minutes longer, another sample is taken, cooled and again tested. When the phenolphthalein shows a very light pink after several minutes, the soap is practically neutral, although at this point one can better judge by dissolving a sample in hot neutralized alcohol made by putting into the alcohol a few drops of phenolphthalein, and then adding weak alkali drop by drop from a burette until a slight pink, not yellow, tint is obtained, and noting the color of the solution. The solution should show a very light pink when the soap is properly neutralized. When this stage is arrived at the gum tragacanth, previously softened in water, is crutched in if it is to be added. The soap is then framed, stripped in three or four days, dried and milled.

The formulae as given are for shaving sticks, and do not readily press unless thoroughly dried. A more satisfactory result is obtained by adding at the mill 25 per cent. of white tallow base to obtain a satisfactory mug soap.

SHAVING POWDER.

Shaving powder differs from the soaps just described in being pulverized, usually adding up to 5 per cent. starch to prevent caking. Any of the above soaps, dried bone dry, with or without the addition of tallow base make a satisfactory powder for shaving.

SHAVING CREAM.

Shaving cream is now a very popular shaving medium due to the rapidity and convenience with which one can shave by the use of this product. Formerly shaving cream was made from the liquid oils like olive oil and a soft fat like lard, together with cocoanut oil. Now, however, most of the popular shaving creams are made from stearic acid and cocoanut oil, as a far superior product is obtained by the use of these substances. By using these a more satisfactory cream is obtained, and it is far more convenient to make. The lather also produced therefrom is more suitable for shaving, being thick, creamy and remaining moist.

A few typical formulae for shaving creams of this type are as follows:

I. lbs.
Cochin cocoanut oil 26
Stearic acid 165
Caustic potash lye, 50deg. B. 69
Glycerine C. P. 76
Water 38

II. lbs.
Cochin cocoanut oil 18
Stearic acid 73
Caustic potash lye, 39deg. B. 54
Glycerine 33
Water 27

III. lbs.
Cochin cocoanut oil 18
Stearic acid 73
Caustic potash lye, 39deg. B. 54
Glycerine 20
Water 40

and lbs.

Stearic acid 60
Glycerine C. P. 85
Water 165
Sodium carbonate 50
Borax 1

To make a shaving cream by Formula I or II, the cocoanut oil and glycerine are first put into a suitable mixing apparatus or crutcher, and heated to 120deg. F. A part or all the potash lye is then added and the cocoanut oil saponified. The rest of the potash lye and the water are then added, and with the mixer running the stearic acid, previously melted in a lead-lined or enameled vessel, is then poured in in a stream and the mass stirred until smooth, care being exercised not to aerate it too much. The cream is then tested for alkalinity, the best method being by that described under shaving soap, in which the sample is dissolved in alcohol. Because of the large quantity of water present, phenolphthalein is unsatisfactory, as dissociation of the soap may show a pink indication in spite of the fact the mass is on the acid side. For a quick method of testing the bite on the tongue is a satisfactory criterion. If a cooled sample bites the tongue more stearic acid is added until there is a 3% excess of this. When the proper neutralization has taken place the cream is perfumed and framed in a special frame, or it may be allowed to cool in the mixer and perfumed the next day. When cool the cream is strained, or put through an ointment mill, after which it is ready to fill into tubes.

The procedure for the first part of Formula III is the same as that just given. The second part of the formula is made the same as a vanishing cream for toilet purposes. To make this, first melt the stearic acid as already directed. Dissolve the sodium carbonate and borax in water and when dissolved add the glycerine and stir. Then heat this solution to about 100deg.-120deg. F. and while stirring in a suitable mixing machine into which this solution has been poured after being heated, or better still in which it has been heated by dry steam, add the stearic acid. Continue mixing until smooth and then allow to cool, or run into frames to cool.

When the shaving cream and vanishing cream are both cool, they are mixed in the proportion of one of the former to two of the latter. It is claimed that in thus making a shaving cream a smoother product is obtained, although it may be said that the vanishing cream is merely a soft soap and the ultimate result is the same as though the various ingredients were added in one operation, rather than making two separate products and then mixing them, thereby considerably increasing the cost of manufacture.

PUMICE OR SAND SOAPS.

Pumice and sand are at times added to soap to aid in the removal of dirt in cleansing the hands. In some cases these soaps are made in the form of a cake, in others they are sold in cans in the form of a paste.

A hand paste is usually made by merely dissolving ordinary tallow base in two or three times its weight of hot water and mixing in the desired quantity of pumice or sand and in some instances adding a little glycerine to keep it soft or a solvent of some kind for grease. It may also be made by directly incorporating any of these in a potash soap.

A cold made or semi-boiled cocoanut or palm kernel oil soap is the base used to add the pumice or sand to in making a cake soap of this sort. The following formulae serve as a guide for these soaps.

I.

Palm Kernel or Ceylon Cocoanut Oil 705 lbs.
Pumice (Powdered) 281 "
Soda Lye, 38deg. B. 378 "

II.

Cocoanut Oil 100 "
Soda Lye, 38deg. B. 55 "
Water 6 "
Silver Sand (fine) 60 "

To proceed place the oil in a crutcher and heat to 140deg. F. Sift in the pumice and mix thoroughly. The lye is then added which causes a curdling of the grain. The stirring is continued until the grain closes and the soap is smooth, after which the desired perfume is added and the soap dropped into a frame and crutched by hand. When the soap is set, it is slabbed, cut into cakes, dried slightly and pressed.

LIQUID SOAPS.

Liquid soaps are merely solutions of a potash soap, usually cocoanut oil soap, although corn oil is used to make a cheap soap. One of the difficulties encountered in liquid soap is to keep it clear. At a low temperature a sediment is often formed, but this can be overcome by the use of sugar and filtering the soap through a filter press at a low temperature. In order to prevent the soap from freezing, it is necessary to lower the freezing point by the addition of glycerine or alcohol.

To make liquid soap by any of the formulae given below, the oil is first run into a jacketed kettle with a stirring device, and heated to about 120deg. F. The potash lye is then added and the oil saponified. When the saponification takes place, especially when cocoanut oil is used, the mass swells rapidly and may foam over the sides of the kettle unless water is used to check this, or a kettle of about four to five times the capacity of the total charge of soap is used. When the saponification has occurred, the sugar, borax and glycerine are added, the water run in and the mixture stirred until the soap is thoroughly dissolved. Heat aids materially in dissolving the soap. The soap is then allowed to cool and if color or perfume is to be added this is stirred in, after which the soap is cooled and filtered or else run directly into barrels.

Tallow is not suitable for making a clear liquid soap since it is too high in stearine which when formed into the stearate makes an opaque solution. The formulae herewith given have been found to give good practical results.

I. lbs.
Cocoanut oil 130
Caustic potash lye, 28deg. B. 135
Sugar 72
Borax 2
Water 267

II. lbs.
Corn oil 130
Caustic potash lye, 26deg. B. 135
Sugar 72
Borax 2
Water 267

III. lbs.
Cocoanut oil 100
Caustic potash lye, 28deg. B. 102
Glycerine 100
Sugar 70
Water 833

Formulae I and II contain about 20 per cent. fatty acids. It is possible, of course, to either increase or decrease the percentage of fatty acid by varying the amount of water. The water used in making liquid soaps, of course, should be soft, for hard water forms insoluble soaps which precipitate and cause a sediment.

USE OF HARDENED OILS IN TOILET SOAPS.

While the introduction of the hydrogenation of oils is a decided advance in the production of suitable cheaper oils for soap making, comparatively little hardened oil is employed for soap making in America up to the present time. In Europe, however, considerable advance has been made by the use of such oils for manufacturing soap therefrom and a number of plants turn out large quantities of hydrogenated oils for soap making as well as for edible purposes. Recently a company has been formed in this country for hardening oils and it is very probable that the future will see this material extensively used in our own country, as these appear to be the one present hope of the soap manufacturer as a check on the ever increasing cost of fats and oils now used in making soap.

It is an unfortunate condition that hydrogenated oils produced abroad are sold under names which give absolutely no indication as to the oil which has been hardened. The softer and cheaper oils like fish oil, linseed oil, cottonseed oil, etc., are generally hardened for soap manufacture to different degrees of hardness. While it is impossible to definitely state just what products as Candelite, Talgol, Krutolin or several other coined names of hardened oils are, various investigators have experimented with them as to their adaptability for producing toilet soaps and found that suitable toilet soaps may be made from them. While many objections were at first met with concerning soaps made from these products, as to their unsatisfactory saponification, the poor lathering quality of the soaps and their odor and consequent difficulty in perfuming, the results of most investigators along these lines indicate that these in many cases were due to prejudice against or unfamiliarity with handling oils of this type for soap making.

In manufacturing soap from hardened oils it is usually necessary to incorporate with the charge lard, tallow, tallow oil or some other soft oil of this nature. Satisfactory bases for toilet soaps, made as boiled settled soap by the use of Talgol (undoubtedly hardened fish oil), are said to be made by the formulae[10] below.

I.

Tallow 45 parts
Talgol 40 "
Cocoanut Oil 15 "

II.

Cocoanut Oil (Ceylon) 6 "
Tallow 12 "
Talgol, Extra 12 "

The method of boiling a soap of this type does not differ materially from that of making settled tallow soap base. The soap itself has a different odor than a straight tallow base, but is said to make a very satisfactory soap for milling and to be of good appearance.

Satisfactory transparent soaps are made from the hardened oil Candelite, which replaces the tallow in transparent soap formulae such as have already been given in the section under "Transparent Soaps." The method of manufacturing a soap by the use of this product varies in no way from the usual method employed for making these soaps.

Since hydrogenated oils are high in stearine, their use in shaving soaps is a decided advantage. It has previously been pointed out that potassium stearate forms an ideal lather for shaving, and in the hydrogenating process the olein is converted to stearine. Thus a hardened oil is advantageous in a shaving soap. As an example of a cold made soap for shaving the following may be taken.[11]

Talgol Extra 50 lbs.
Cocoanut Oil 10 "
Lard 10 "
Soda Lye, 38deg. B. 20 "
Potash Lye, 37deg. B. 21 "

This soap may be made in a crutcher by the method generally used in making soap by the cold process.

TEXTILE SOAPS.

Soap is a very important product to every branch of the textile industry. For woolen fabrics it is used for scouring, fulling and throwing the wool; in the silk industry it is necessary for degumming the raw silk, as well as for dyeing; in the cotton mills it is used to finish cotton cloth and to some extent in bleaching; it is, furthermore, employed in a number of ways in the manufacture of linen. Large quantities of soap are thus consumed in an industry of so great an extent and the requirements necessitate different soaps for the different operations. We will, therefore, consider these in detail.

SCOURING AND FULLING SOAPS FOR WOOL.

The soaps used to scour wool and for fulling the woven cloth are usually made as cheaply as possible. They are, however, generally pure soaps, as filling material such as sodium silicate does not readily rinse out of the wool and if used at all must be added very sparingly. Both cold made and boiled settled soaps are made for this purpose. The soap is generally sold in barrels, hence is run directly to these from the crutcher or soap kettle. As cold made soaps the following serve for wool scouring or fulling.

I.

Palm Oil 200 lbs.
Bone Grease 460 "
Soda Lye, 36deg. B. 357 "
Water 113 "
Soda Ash 50 "
Citronella 2 "

II.

Palm Oil (Calabar, unbleached) 155 "
House Grease 360 "
Soda Lye, 36deg. B. 324 "
Water 268 "
Sodium Silicate 83 "

III.

House Grease 185 "
Palm Oil (unbleached) 309 "
Soda Lye, 36deg. B. 309 "
Water 391 "
Soda Ash 70 "
Sodium Silicate 60 "
Corn Starch 10 "

These soaps are made in a crutcher by the usual process for cold-made soaps, crutched until smooth, dropped into a barrel and crutched by hand the next day or just before cooling.

As a settled soap for these operations the following charge is typical:

Palm Oil 34 parts
Cottonseed foots or its equivalent in fatty acids 33 "
Rosin 10 "
House Grease 23 "

The method of boiling such a soap is the same as for any settled soap up to the strengthening change. When this stage is reached, sufficient lye is added to strengthen the kettle strongly. It is then boiled down with closed steam on salt brine or "pickle" until a sample of the lye taken from the bottom stands at 16deg.-22deg. B. The soap is then run into barrels and after standing therein for a day is hand crutched until cool to prevent streaking of the soap.

Besides a soap of this type a settled tallow chip soap is used.

WOOL THROWER'S SOAP.

Soaps for wool throwing are sometimes made from olive oil foots but these are often objected to because of the sulphur-like odor conveyed to the cloth due to the method by which this oil is extracted with carbon disulphide. A potash soap hardened somewhat with soda is also used. As a formula for a suitable soap of this type this may be given.

Olive Oil Foots 12 parts
Corn Oil 46 "
House Grease 20 "
Soda Lye, 36deg. B. 3 "
Potassium Carbonate (dry) 5-3/4 "
Potassium Hydrate (solid) 23 "

This soap is made as a "run" soap by the general directions already given for a soap thus made. The kettle is boiled with open and closed steam, adding water very slowly and aiming to obtain a 220-225 per cent. yield or fatty acid content of the finished soap of 46 per cent. When the soap is finished a sample cooled on a plate of glass should be neither slippery or short, but should string slightly. The finished soap is run directly into barrels.

A soap for wool throwing by the semi-boiled process may be made from olive oil foots in a crutcher thus:

Olive Oil Foots 600 lbs.
Potash Lye, 20deg. B. 660 "

The oil is heated to 180deg. F., the lye added and the mass stirred until it bunches, when it is dropped into barrels.

WORSTED FINISHING SOAPS.

For the finishing of worsted cloth soaps high in cocoanut oil or palm kernel oil are preferred. These soaps are finished very neutral, being made as settled soaps, but given an extra wash change after strengthening strongly. They are then finished as usual and run into barrels. If framed too hot, the high percentage of cocoanut oil causes mottling, which is prevented by crutching by hand until the temperature of the soap is 140deg.-145deg. F. Some typical charges, all of which are saponified with soda lye, follow:

I.

Palm Kernel Oil 60 parts
Corn Oil 40 "

II.

Palm Kernel Oil 30 "
Red Oil (single pressed) 70 "

III.

Red Oil 33-1/3 "
Corn Oil 33-1/3 "
Cocoanut Oil or Palm Kernel Oil 33-1/3 "

SOAPS USED IN THE SILK INDUSTRY.

Soap is used to a very large extent in silk mills, both for degumming the raw silk and in silk dyeing. Raw silk consists of the true silk fibre known as fibroin and a gummy coating, sericin, which dulls the lustre of the silk unless removed. For this purpose a slightly alkaline olive oil foots soap is best adapted, although palm oil and peanut oil soaps are sometimes used, as well as soaps made from a combination of house grease to the extent of 30 per cent., together with red oil or straight olein soaps, both of which are artificially colored green. In using house grease, if 30 per cent. is exceeded in combination with red oil, the titer is raised to such an extent that the soap does not readily rinse from the silk nor dissolve readily. They are also not advisable because they impart a disagreeable odor to the silk.

To make a soap for this purpose from olive oil foots it is made as a settled soap, care being taken to thoroughly boil the mass on the saponification change in the closed state to assure proper saponification. The kettle is usually grained with lye and given a good wash change to remove the excess strength. The change previous to the finish should not be too heavy or too large a nigre results. The lighter the grain is, the better the finished kettle is. A yield of 150 per cent. is usually obtained. This soap is generally run to a frame, slabbed upon cooling and packed directly into wooden cases.

For silk dyeing the above soap is suitable, although any well-made soap of good odor and not rancid is useable. While soap alone is often used in the bath for silk dyeing, certain dyestuffs require the addition of acetic or sulphuric acid, which sets free the fatty acids. If these be of bad odor it is taken up by the silk and is difficult to remove. The most generally used soaps are the just mentioned olive foots soap or a soap made from a good grade red oil.

Both kinds are extensively used.

SOAPS USED FOR COTTON GOODS.

In the manufacture of cotton goods, as compared to the wool and silk industries, very much less soap is used and it is only applied to the finished fabric either to clean the cloth preparatory to dyeing or to aid in dyeing with certain colors. It is also used in calico printing. For cleansing the cloth ordinary chip soap is suitable although a more alkaline soap finished as a curd soap is an advantage in that the free alkali contained therein aids in removing the dirt and has no harmful effect on the cotton. For dyeing cotton goods or to brighten certain colors after dyeing an olive oil foots soap is most generally employed. In calico printing soap is used to wash and clear the cloth after printing. A soap for this purpose should be easily soluble in water and contain no free alkali, rosin or filler. The best soaps for use in calico printing are either an olive oil foots soap or an olein soap.

SULPHONATED OILS.

While sulphonated oils are not used to any great extent in the manufacture of soap, they are used very largely in the dyeing and printing of turkey and alizarine reds on cotton as well as other colors. Just what action these oils have is not known. Turkey red oil or sulphonated castor oil is the best known sulphonated oil.

The process of making these oils is simple. The equipment necessary is a wooden tank or barrel of suitable capacity, approximately two and a half times the amount of oil to be treated. There are furthermore required other tanks or vessels to hold the solutions used such as caustic soda, ammonia and acid. The tank to be used for the preparation of sulphonated oil should be provided with a valve at the bottom of the tank and a gauge to measure the quantity of liquid therein.

The process is carried out as follows:

Three hundred pounds of castor oil are placed in the tank and 80 pounds at 66 deg. B. sulphuric acid are weighed out in another vessel. The acid is run into the tank containing the oil in a very thin stream while the oil is well stirred. At no time should the temperature exceed 40 deg. C. This operation should consume at least an hour and stirring should be continued half an hour longer to insure the thorough mixing of the oil with the acid. The mass is then allowed to settle for 24 hours, after which 40 gallons of water are added and the mixture stirred until it has a uniform creamy color indicating no dark streaks. This mixing process should be carefully carried out and when completed allowed to settle 36 hours. At this point the mass will have separated into two layers, the lower layer consisting of a water solution of acid and the upper layer of oil. The former is run out through the valve located at the bottom of the tank. Another wash may now be given or dispensed with as desired. In this wash the addition of salt or sodium sulphate at the rate of 1-1/2 pounds per gallon of water is advisable. A 24 deg. B. caustic soda solution is prepared and added slowly to the acidified oil with constant stirring. The mass first turns creamy, then becomes streaked, increasing in streaks as the caustic solution is poured in, and finally becomes clear and transparent. Water is now added to bring the volume to 75 gallons. The oil is now milky in appearance, but the addition of a little more soda solution restores the transparency.

In some cases ammonia is used in addition to caustic soda in neutralizing the oil. Three-fourths of the amount of caustic soda required to complete the neutralization is first added and then the neutralization is completed with a one to one liquid ammonia and water solution.

FOOTNOTES:

[9] Seifensieder Ztg., 40, 47, 1266 (1913).

[10] Seifensieder Ztg. (1913), p. 334 and 338.
" " (1912), p. 1229 and 1257.

[11] Seifensieder Ztg. (1912), p. 954.