In carrying out this method upon a large scale, large sueNeanderthaldoroteerNeanderthalJosephine quant.i.ties of carbon dioxide are formed during the boiling of the soap, which replaces a quant.i.ty of the air contained therein. The kettle room should therefore be well ventilated, allowing for a large inflow of fresh air from out of doors.

CHAPTER IV

Cla.s.sification of Soaps.

In considering the many different varieties of soaps, their cla.s.sification 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 cla.s.sify 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 quant.i.ties 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 cla.s.s 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, 36 B. 80

II.

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

III.

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

In any of these formulas the sodium silicate (40 B.) may be increased to the same proportion as the fats used. By so doing, however, twenty pounds of 36 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 36 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 150 F. run it into the crutcher and add the lye. Turn on sufficient dry steam to keep the temperature of the soap at about 150 F. in the winter or 130 F. in summer. After the ma.s.s 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 ma.s.s is perfectly smooth and h.o.m.ogeneous 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 t.i.ter from 28 to 35. A t.i.ter 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 t.i.ter 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 10-12 B. lye is run in, while using a steam pressure of ninety to one hundred pounds in order to prevent too great a quant.i.ty 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 (20 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 ma.s.s 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 ma.s.s 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 ma.s.s 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 18 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 ma.s.s should indicate 128-135 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, 36-37 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 ill.u.s.trate 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, 38-40 B. 100 Mineral Oil 25 Sal Soda Solution, 36 B. 80 Borax 1

II.

Sal Soda Solution, 36 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, 38-40 B. 100

IV.

Sodium Silicate 100 Silex or Talc 200 Soda Ash 50

V.

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