How to Make? An Improved Soap .. Not just for more Foam (GTZ, 1993, 71 p.) D. Saponification of fat mixtures D.I. General informations D.II. Equatorial zone D.III. Humid tropical zone D.IV. Semiarid tropical zone

How to Make? An Improved Soap .. Not just for more Foam (GTZ, 1993, 71 p.)

D. Saponification of fat mixtures

D.I. General informations

Soap-making fats have very different physical and chemical properties and this is reflected on the quality and characteristics of the soaps they generate. By practicing composition of fat mixtures, the soap maker has the opportunity to manufacture soaps with various qualities for usage.

A soap used for instance for washing should be mainly composed of fats (at least 3/4 of the weight of the mixture) which soaps have good to very good cleaning properties.

Soap used for body hygiene on the contrary should mainly contain fat which develop a smooth to very smooth effect on the skin.

To make consistency soaps, you should use caustic soda solutions and choose as main components (at least 2/3 of the weight) of the mixture fat which produce hard to very hard soaps (refer to table II for details).

In practicing the various recipes, the soap maker may be limited i.e. by the availability of fats in his ecological zone and also by the cost.

In the upcoming lines, we propose recipes based on the locally available fats for each of the 3 main ecological zones of developing countries.

As soap-making techniques, the cold and semi-hot process are chosen due to their simplicity and also to the weakness of the energetic needs for their implementation.

D.II. Equatorial zone

The main soap making fats available in this zone are: copra, palm, palmist oils as well as pork fat. The first three fats are very easy to saponify even at cold, while the saponification of pork fat as such requires some cleverness.

For soaps used for body hygiene, the mixture of fat bodies should contain mainly palmoil and/or pork fat due to the smooth effect their soaps have on the skin.

For the cold process of soap making, some proportion of copra or palmist oil in the mixture is however indicated in order to ensure a quick starting of the cold saponification

D.II.1. Cold process

Recipes (kg)
	A	B	C	D
Copra	-	10	-	-
Palmist	10	-	30	-
Palm	90	50	70	60
(Pork) fat	-	40	-	40
Caustic potassium at 15 °Be	-	19	53,90	-
Caustic soda at 35 °Be	50,70	-	-	49
Caustic soda at 40 °Be	-	36,6	28,70	-
Salt	-	-	5	-
Kaolin	5	-	-	-
Colors & scents	-	0,1	-	0,1
INS Factor of fats mixture	157	151	174	141

The composition A & C give soaps used for washing while the B an D generate soaps used for body hygiene.

Soap preparation

In analogy with preparation of soap based on isolated fats, it is composed of pretreatment and saponification stages.

The pretreatment consists mainly in the purification of fat. The simple method of washing (successive eventually) in salted boiling water can be used to that end (refer to chapter on peanut oil for detailed description). Palm oil must be bleached (decolorated) before entering in mixture composition (refer to the detailed description of the bleaching techniques in chapter about palm oil)

How to conduct the operations:

- Weigh the necessary quantities of purified fats and put them in the boiler;
- Heat it up to 40 °C, stir and make sure that all the components are well melted;
- Stop the heating and add the alkaline solution by stirring (formation of an emulsion);
- When the emulsion do appears, add the strong alkaline solution by stirring intensively;
- Go on stirring until the appearance of an increased stickiness of the mass;
- Add the additives (secondary products, color and scent) by stirring in order to ensure their incorporation;
- Pour the hot mass into big moulds;
- Close well the moulds in order to keep in the heat of the reaction;
- After the blocks get cold and hard, take them out of the moulds and cut them into bars and (eventually into pieces).

D.II.2. Semi-hot process

Recipes (Kg)
	A	B	C	D
Copra oil	-
Palmist oil	10	-	20	-
Palm oil	9o	80	8o	50
Fat	-	20	-	40
Beewax	-	-	5	-
Caustic potassium at 15 °Be	-	-	35,90	18,60
Caustic soda at 15 °Be	46	-	-	-
Caustic soda at 35 °Be	-	49,50	-	-
Caustic soda at 40 °Be	28,70	-	32,70	36,60
Water	-	5	-	-
Filling material	5	-	5	-
Colors & scents	-	0,1	-	0,1
INS Factor of fat mixture	157	145	165	151

The compositions A and D generate soaps used for washing while B and D produce soap to be used for body hygiene.

Soap preparation

The fats for the composition of the mixture should be pre-treated. The simple techniques appropriate for this are described in each category of fat raw materials. Particularly palm oil should be bleached.

How to conduct the operations:

- Weigh the quantities of purified fats;
- Put then into the boiler and heat at 55 - 60 °C;
- Stop heating and add the alkaline solution in small portions by stirring (start with the weak alkaline solution);
- Stir from time to time (the temperature increases progressively up to a maximum and then starts to decrease);
- Let the temperature decrease down to 55 - 60 °C;
- Add the secondary products (additives, color and scent) by stirring well for their incorporation;
- Pour the hot mass into moulds;
- Let it become cold and hard;
- Take the blocks out of the moulds and cut into bars (and eventually into pieces).

D.III. Humid tropical zone

It is the ecological zone presenting the widest range of fats for saponification. Among them you can find those of animal origin such pork fat and tallows and those from cultivated plants such as cotton, peanut, physic nut and castor oils and those produced from wild plant fruits such as palm and Manan (Lophira lanceclota) oil and shea (karitea) butter.

All these fats produce good laundry soaps. For toilet soaps, the choice should be oriented towards the following fats: peanut, palm oils, karitea butter and pork fat.

However castor plant and palm oils are the only ones which are easily adapted to cold saponification. Preparation recipes according to that techniques should be composed of high proportions of one or the other of these two fats.

D.III.1. Cold process

Recipes (Kg)
	A	B	C	D
Palm oil	40	40	20	-
Pourghere oil	-	-	50	20
Castor plant oil	60	40	30	40
Pork fat	-	20	-	40
Caustic soda at 35 °Be	-	47,70	47,70	47,70
Caustic soda at 40 °Be	38,70	-	-	-
Water	1O	-	-	-
Filling material (salt)	5	-	5	-
Colors & scents	-	0,1	-	0,1
INS Factor of fat mixture	118	124	111	111

The compositions A and C produce soap for the washing while B and D produce soaps used for body hygiene.

Soap preparation

The pre-treatment of fats consists in the purification (and eventually bleaching). The usage techniques are those already precited.

How to conduct the operations:

- Weigh necessary quantities of purified fat and put them into the boiler;
- Heat slightly up to 40°C, mix and make sure that all components are melted;
- Stop the heating and add under stirring the weak alkaline solution by portions;
- Go on stirring until the appearance of high slickness of the mass;
- Add the secondary products (additives, color and scent) by mixing to ensure a good incorporation of all products;
- Pour the mass into big moulds;
- Close well the moulds for a good conservation of the heat from the reaction;
- When the blocks get cold and hard take them out of the moulds and cut into bars (and eventually into pieces).

D.III.2 Semi-hot process

Recipes (Kg)
	A	B	C	D	E	F
Peanut oil	-	50	-	-	-	-
Cotton oil	20	-	-	-	30	-
Karitea (Shea) butter	50	-	50	30	40	30
Pork fat	-	20	-	-	-	20
Palm oil	-	30	-	40	30	50
Pourghere oil	30	-	25	-	-	-
Manan oil	-	-	25	-	-	-
Beef suet	-	-	-	30	_	_
Caustic soda at 15 °Be	27,50	28	34	-	28	-
Caustic soda at 35 °Be	-	-	-	48,40	-	48-50
Caustic soda at 40 °Be	31,40	31,60	29,12	-	31,60	-
Water	-	-	-	5	-	5
Filling material (salt)	-	-	5	-	-	-
Colors & scents -	-	0,1	-	00,1	-	0,1
INS Factor of fats mixture	125	118	119	145	121	1338

A, C and E compositions are used to make laundry soaps
B, D and F give soaps for body hygiene

Soap preparation

Karitea (shea) butter, pourghere, palm, cotton and peanut oils, pork fat and tallow constitute the main fats appropriate for semi-hot saponification.

Cotton and palm oils should be treated (bleached) before being incorporated into the fat mixture. The bleaching of palm oil is done by thermic treatment while cotton oil is bleached by treatment with alkaline (see the point on the saponification of this fat for technical details).

Karitea butter should also be deodorized. A prolonged cooking with 50% of the fat volume of water is efficient in this purpose.

For other above-mentioned fat the washing in salted boiling water is the simplest method for purification.

You must however notice in this scope that raw pourghere oil develops sometimes a great tendency to form stable emulsions which phase separation can require 48 hours.

In some cases, depending from the used extraction technique, filtering may enough for purification.

How to conduct the operations:

- Weigh the quantities of purified fat and heat in the boiler at about 55 - 60 °C;
- Stop the heating and add the alkaline solution in small portions by stirring (eventually start with light intake alkaline solution);
- Go on stirring for a few minutes (the temperature starts increasing);
- Stir from time to time until the temperature of the mass gets to a maximum;
- Let the temperature get down to 55 - 60 °C and add the secondary products (additives, colors and scent) and mix well for good incorporation;
- Pour the mass which is still hot into moulds, let it get cold and hard;
- Take the blocks out of the moulds and cut into bars (eventually into pieces).

D.IV. Semiarid tropical zone

The range of fats used for soap making is very limited in this ecological zone. The neem and peanut oils and tallows scow, mutton) and eventually milk butter constitute the main available fats. Neem oil produces bad odor soaps which however have very good cleaning qualities.

Considering their properties, these fats are not well appropriate for saponification by cold process.

However in some sahelian zones, a traditional technique of saponification at cold is used: the cold saponification of the powder from kernel of Balanites aegyptiaca.

The process consists in:

- well mixing in a wide opening container the powder of kernel and a strong alkali (caustic potassium or soda) in a ratio of 15 to 20 volumes of powder for 1 volume of alkali;
- Pour progressively on the mixture an equal volume of boiling water by stirring;
- Let it then become cold and hard.

D.IV.1. Semi-hot Process

Recipe (Kg)
	A	B	C	D
Peanut	50	40	-	30
Neem	-	-	50	40
Tallow (mutton)	50	-	50	-
Tallow (cow)	-	60	-	30
Caustic soda at 15 °Be	37	388	39	39
Caustic soda at 40 °Be	28,70	288,70	28,70	28,70
Water	-	-	12,50	110
Salt	-	-	1,25	1
Filling material (kaolin)	2	-	-	-
Color & scent	-	0,1	-	0,1
INS Factor of fat mixture	126	132	142	126

A and C are used for washing soaps.
B and C give toilet soaps.

Soap preparation

The fats can be treated using the precedently mentioned methods.

For recipes containing neem oil (C and D) this should be saponified apart and the obtained soap grained out (for details refer to point about neem oil).

The excess lye contains bad odorous and colorous matters and impurities. It must be drained out.

The pure soap is then melted and mixed with other fat . The saponification is then started a new by addition of the necessary additional quantity of alkaline.

How to conduct the operations to prepare compositions A and B:

- Weigh the necessary quantities of purified fat and put them into the boiler;
- Stop heating and add the light alkaline solution in small portions by stirring;
- GO on stirring during a few minutes (the temperature starts increasing);
- stir from time to time until the temperature of the mass reaches a maximum;
- Let the temperature of the mass get down to 55 - 60 °C and add the secondary products (additives, color, scent) and mix well to get incorporation;
- Pour the mass which is still hot into moulds let it get cold and hard;
- Take the blocks out of the moulds and cut into bars (and eventually' pieces).