Retro Formulas

By Roberto Ribeiro. Aragon

This book brings several original contributions to research and practical applications in the field of new product development, based on the experiences of the first industrialization periods .

It presents objective models in the form of formulas and recipes for the manufacture or industrialization of many items in various segments of the industry.

It aims to disseminate concepts and techniques with differentiated approaches, since materials and processes go back to past times, for a theoretical investigation, in addition to the proven applications in mass manufacturing systems.

• Language: English
• Publisher: Roberto Ribeiro. Aragon
• Release date: Feb 20, 2020
• ISBN: 9780463597989

Book preview

Brief Vocabulary of Expressions

EXPLANATIONS OF THE SPECIAL TERMS USED

THIS WORK INSTRUCTIONS ON THE

USE OF VARIOUS MATERIALS.

Acids. Acids, bleaches and, in general, all attacking liquids should be kept in thick glass bottles with ground-up lids. Cork and wood are destroyed by most of these attacking liquids, which is why they are not used for this purpose. Vapor-releasing acids, such as muriatic acid or nitric acid, should always be kept in cool places; otherwise, the developed gases lift the lid and can escape. The acid decomposes under the influence of light, forming red vapors. For this reason, the acid should be stored in dark places.

Areometer. Areometers are devices for determining the specific weight of a liquid, its concentration, Baumé degrees, etc.

Attack (Cauterize). To attack with cheeks (solvents) means to produce engravings on the surface of some object, by means of a solvent.

Hone. Burnishing is applying a layer of dark brown color over metallic objects, by means of certain solutions.

Calcinate. Calcining is the removal of water from aqueous salts by heating.

Cauterize. (Cauterization) See attack.

Clarify. (Clarification) Clarifying a liquid means the removal of solid particles in suspension that cannot be removed by filtration. For clarification, appropriate media are used, such as albumin, mass of filter paper (cellulose), kaolin.

Strain. Remove coarse undissolved particles from a liquid, passing it through a more or less thin cloth.

Decant. (Decantation) It is the careful separation of a liquid from a solid body so that the solid body, at the bottom of the container, is not dragged.

Decrepitate. (Decrepitation) It is the cracking of saline crystals due to the formation of crystalline water vapor during heating.

Dehydrate. (Dehydration) See calcine.

Distill. Distillation is the process of transforming a body into steam, upon heating, and cooling it in appropriate facilities, returning it back to its original solid or liquid form. Distillation is performed to separate one or more substances from a solution.

Digest. Digest is to dissolve a solid substance using an appropriate liquid at a temperature of ca. 50 °

Dissolve.  (Dissolution) A distinction must be made between dissolving and solving. Dissolve means the chemical action of a solvent on a substance to be dissolved, by which a new compound is formed.

Electrolysis. Electrolysis is the decomposition of a liquid or solid by means of an electric current, into two components

Enamel.  (Enameling) It is the application of a thin layer of a kind of glass of easy liquefaction, intransparent, to protect the objects thus treated against oxidation or other harmful influences.

Evaporate. (Evaporation) Evaporating is to volatilize a liquid, contained in a mixture or solution, in whole or in part, by heating, to obtain a concentrated solution or a body, solved in it, in solid form.

Evaporate in a vacuum. In this process, evaporation takes place in a low pressure place, whereby the boiling point is lowered, accelerating the volatilization.

Extract. Extract is the product obtained by the extraction (that is, the solvent, in which the components extracted in dissolved form are contained). Liquid, viscous and solid extracts are distinguished.

To extract. Using a suitable solvent, the soluble components are extracted from a substance.

Filter. (Filtration) To filter is to release a liquid from solid particles, suspended in it. Filter paper, cotton, glass wool, etc. are used for this purpose.

Electroplating. Thus it is called a process by which a thin layer of another metal is produced on one metal by means of electrolysis. Small metal objects can also be produced with this process.

Impregnate. (Impregnation) It is to infiltrate a liquid in a solid body (fabric, wood, etc.), in order to make this body refractory or impermeable, or also to protect it from the weather or other harmful influences. Turn on. (Bonding)

Bonding is an intimate mixture of two or more metals, obtained through collective fusion. The metal of the highest melting point must always be melted first.

Leach. (Leaching) It is the process of treating a substance with a solvent until it no longer contains soluble matter. Flammable materials.

This group especially includes easily volatile liquids, whose vapors are flammable. These liquids are: alcohol, acetone, petroleum ether, carbon sulfide, etc.

Macerate. Macerating means leaching a solid substance with an appropriate solvent for a longer period of time.

Neutralize. (Neutralization) To neutralize a base is to treat it with acid (or vice versa) until its basic reaction (acidic response) is eliminated. This point is characterized by the color change of an appropriate substance.

Oxidize. (Oxidation). To oxidize is to cause the composition with oxygen. Reduction is the opposite, namely: the elimination of oxygen.

Precipitate. (Precipitation) It is the production of a solid body by mixing two saline solutions that decompose each other, giving rise to the formation of an insoluble compound.

Rectify. (Rectification) It is the purification of a liquid through repeated distillation.

Reduce. (Reduction) See oxidize.

Regenerate. (Regeneration) It is making objects previously unusable usable. Welding. (Weld)

I. The union of two metal surfaces of the same or different class) is thus called by surface melting 'by means of an easily melting metal alloy.

II. Union of metallic surfaces, by means of the flame, obtaining an intense fusion with the addition of a material similar to the weld (Caldear).

Solver. (Solution) Solver is the fine parting of a liquid or solid body in a liquid in such a way that the parted particles are no longer visible to the human eye. In this solution, there is no chemical transformation of the solvent body or the solvent liquid. By simple evaporation, the unchanged substance can be recovered.

Vulcanize. (Vulcanization) Vulcanizing is the treatment of rubber with sulfur, making it resistant to cold, heat, mechanical stress, etc.

METAL INDUSTRY

ENGRAVING

To etch metals by surface attack as acids, proceed as follows: The places on the surface that should not be modified are covered by a protective layer, while the uncovered parts are attacked little by little by means of an acid or other suitable solvents. When the engraving corresponds to the excavated parts of the metal, we speak of a low relief engraving; when the drawing is prominent, while the background is accentuated, there is talk of a high relief engraving.

For low relief engraving, a protective layer is applied over the entire metal surface, after careful washing. After drying, the design or the signs to be recorded are recorded. For high relief engraving, signs with lithographic ink are applied to the clean surface of the metal, which can be done, e.g. by means of a rubber stamp.

To increase the protective effect, finely powdered rosin can be applied, or a mixture (finely ground) of equal parts of mastic and asphalt, which adheres to the signs. The dust must be retained from other places. Light heating causes the powder to melt, thus obtaining a resistant protective layer.

In the case of a slight superficial engraving of the metal, the striker can be applied directly to the metal by means of a rubber stamp. To wet the stamp, a glass plate is used, in which a piece of linen is found, impregnated with the attacker. After recording, the attacker's waste must be removed. When it comes to iron or steel, oil or kerosene should be applied.

Stamps for this purpose must be harder than ordinary ones. The letters or signs must be narrow, because the engraving always becomes wider than the stamp.

Similar effects can be obtained through mechanical engraving using a sandblast. In place of the protective layer, patterns are used.

The protective layer for recording.

1. Melt carefully in an enameled iron container, in equal parts: asphalt, rosin and beeswax; the dough is removed from the heat, allowed to cool and 10 parts of turpentine oil are added; then the container is put back on fire and heated carefully until complete dissolution. The dough is ready for use and is kept in tightly closed cans.

2. An excellent protective layer is obtained through the following recipe: 4 parts of yellow wax - 4 parts of asphalt - 1 part of black tar - 1 part of white burgundy tar. These substances are melted together, adding 4 parts of pulverized asphalt during the melting. After that, the dough is kept in a melted state, until a test becomes brittle, dropping it on a stone. At this point, the container is removed from the fire, allowed to cool slightly and 30 parts of turpentine oil are added under revolution.

3. 1 parts of tar - 1 part of asphalt - 1 part of gutta-percha - are melted together and applied in a hot state.

Protective layer for copper engraving.

4 parts of wax - 2 parts of rosin - 1 part of Burgundy tar are melted together, and 4 parts of Syrian asphalt are added. For the application, the putty is wrapped in a fine linen cloth and pressed slightly against the metal surface, slightly heated. A viscous solution of the dough in an easily volatile solvent such as benzol, benzine, etc., can be applied with a brush.

Etching mixtures of acids such as muriatic acid, nitric acid, sulfuric acid, etc., and saline solutions are used. The application of acids causes the release of harmful gases, which is not the case with saline solutions.

Bronze striker.

100 parts nitric acid - 5 parts muriatic acid. Striker for engraving in low relief.

10 parts of muriatic acid - 2 parts of potassium chlorate - 88 parts of water.

1. Generally diluted nitric acid is used: for the beginning of the recording an acid prepared with 4 ... 8 parts of water and a part of concentrated acid is used, while for the deeper recording a mixture of parts is used equal amounts of water and concentrated acid.

2. A 40 ... 50% iron perchloride solution. 3. A saturated solution of ammonium chloride and copper.

4. A solution of 20 g of sublimated mercury in 450 g of water, mixed with 1 g. of tartaric acid or 20 drops of nitric or muriatic acid. The addition of 5 ... 10 drops of an antimony chloride tartrate solution (antimony trisulfide) accelerates the effect.

5. For high speed steel. A mixture of nitric acid (1,2) and muriatic acid (1,12) in a ratio of 1: 2, by volume. It also serves muriatic acid (1.12) with an addition of bromine or muriatic acid, to which, occasionally, a little potassium chlorate is added.

Striker for copper and brass.

1. Diluted nitric acid.

2. Diluted nitric acid, to which, from time to time, a little potassium chlorate or potassium bichromate is added.

3. 200 grams of iron perchloride, in 0.5 liters of water, with a small addition of muriatic acid or potassium chlorate.

Mixtures of acids, such as muriatic acid, nitric acid, sulfuric acid, etc., and saline solutions are used for recording. The application of acids causes the release of harmful gases, which is not the case with saline solutions.

Bronze striker.

100 parts nitric acid - 5 parts muriatic acid.

Striker for engraving in low relief.

10 parts of muriatic acid - 2 parts of potassium chlorate - 88 parts of water.

1- Generally diluted nitric acid is used: for the beginning of the recording, an acid prepared with 4 ... 8 parts of water and one part of concentrated acid is used, while for the deeper recording a mixture of parts is used equal amounts of water and concentrated acid.

2- A 40 ... 50% iron perchloride solution.

3- A saturated solution of ammonium chloride and copper.

4- A solution of 20 g of sublimated mercury in 450 g of water, mixed with 1 g. of tartaric acid or 20 drops of nitric or muriatic acid. The addition of 5 ... 10 drops of an antimony chloride tartrate solution (antimony trisulfide) accelerates the effect.

5- For high speed steel. A mixture of nitric acid (1,2) and muriatic acid (1,12) in a ratio of 1: 2, by volume. It also serves muriatic acid (1.12) with an addition of bromine or muriatic acid, to which, occasionally, a little potassium chlorate is added.

Striker for copper and brass.

1. Diluted nitric acid.

2. Diluted nitric acid, to which, from time to time, a little potassium chlorate or potassium bichromate is added.

3. 20 grams of iron perchloride, in 0.5 liters of water, with a small addition of muriatic acid or potassium chlorate.

4- To apply brass stamps. 2 parts of antimony chloride with one part of sublimated are dissolved in little muriatic acid. In place of sublimation, copper chloride or bismuth chloride can also be used.

5- Striker for brass. 3 parts of potassium chlorate are dissolved in 50 parts of water. Separately, 8 parts of nitric acid (1.40) are mixed with 80 parts of water. Finally, the two liquids are mixed.

Striker for zinc.

2 parts of crystallized copper chlorate and 3 parts of copper chloride are dissolved in 64 parts of distilled water and then mixed with 8 parts of muriatic acid (1,1). Dipping a zinc sheet with a purely metallic surface into this liquid, it instantly turns black. After washing with pure water, the black layer adheres firmly to the zinc. High relief engraving with zinc is carried out by applying letters or signs using this liquid, on a thick zinc plate. After drying the liquid, the plate is immersed in a mixture of 1 part of nitric acid and 8 parts of water, for 1 ... 3 hours. Zinc is attacked, while letters or signs are in high relief.

Aluminum engraving.

Distilled water 1000  grams- Alcohol 100grams- Acetic acid 175 grams- Antimony protochloride 100grams

Lead engraving.

Distilled water 1000grams - Alcohol 100grams- Tin bichloride 75grams

Silver engraving.

1000 g of distilled water - 25 g of royal water - 30 g of alcohol - 2 g of silver acetate.

Gold engraving.

1000 g of distilled water - 50 g of royal water - 35 g of alcohol - 10 g of tin bichloride.

TEMPERING OF METALS.

Way to regulate the tempering and annealing temperatures of the steels.

The exact regulation of the temperature is very difficult because it is often slightly different from the temperature of the breather. oven. In order to be able to exactly control the temperature inside the oven, the salts listed below are used, salts whose melting points are known. When the salt melts on the metal surface, the piece can be removed from the oven.

Intermediate temperatures can be obtained through conveniently dosed saline mixtures. For example, between 810 and 8650.

8500: with 5 grams of potassium sulfate and 5 grams of sodium sulfate.

8300: with 3 grams of potassium sulphate and 7 grams of sodium sulphate.

8250: with 2 grams of potassium sulphate and 8 grams of sodium sulphate.

The cheapest bath for tempering is water. However, its application can be recommended only when tempering is performed by people who have some experience. The temperature of the water bath must be very uniform at 27 °. With a much higher temperature, tempered objects are not hard enough. Generally, it is determined, by previous experiments, which is the most suitable temperature for the material in question, then maintaining it during the work with that material.

Quenching in water baths.

These baths generally consist of saline solutions, with the occasional addition of acids.

The most used formulas are as follows:

For springs: 100 grams of water - 41 grams of black soap. - For files and scrapers: 25 grams of table salt - 5 grams of ammonia salt - 1100 grams of water - for very hard tools: 3 grams of sulfuric acid - 150 grams of alcohol - 1000 grams of table salt - 10,000 grams of Water.

For matrices: 50 grams of potassium carbonate - 200 grams of water

For the tempering of limes, a mixture of 5 parts of horn dust - 5 parts of charcoal powder - 2 parts of pulverized table salt - is also recommended - 0.5 parts of potassium nitrate - 1 part of potassium ferrocyanide. This mixture is suitable for spreading files.

Quenching paste for tools in the quarry and marble industry.

700 parts of rosin - 300 parts of potassium ferrocyanide - 100 parts of copper sulphate - 100 parts of linseed oil. These components are boiled under a continuous revolution, until a residue of 1000 parts remains (which corresponds to a volatilization of 200 grams). The dough is poured into boxes in which it solidifies into a fragile dough. To use this mass, the steel part is heated to a live glow, and the mass is touched with it, which softens instantly due to the influence of the heated tool. In the case of good steel, just heat the part again and cool it down abruptly. By this treatment, the steel becomes not only very hard, but also extraordinarily tenacious. A steel of inferior quality must be touched with mass 2 up to 3 times, consecutively, after having been reheated each time.

Another saline bath for tempering tools.

Table salt is appropriate because its melting point is at the same temperature as the tool quench (ca. 750 °). The bath is prepared as follows: at the bottom of a crucible, a layer of sodium carbonate is placed and the crucible is then filled with table salt. The melting is initiated by the sodium carbonate which has a lower melting point. Advantageously, a little bit of potassium or saltpeter chromate can be added. The temperature mentioned above must be maintained. The excess temperature produces a movement of the melted mass. The objects to be tempered must be well cleaned, defatted and heated. Adherent moisture in them produces an effervescence of the mass. The objects are suspended in the mass through thin wires. This hardening process protects the parts against oxidation.

Regeneration of overly oxidized (burnt) steel tools.

1. 500 g of tallow are melted with 112 g of black tar, under continuous revolution, and 325 g of powdered ammonia salt are added - 125 g of potassium ferrocyanide - 20 g of soap - ca, 100 g of salt of kitchen. In an incandescent state, the tools are immersed in this mass, allowing them to cool. After that, tempering is carried out in the common and known way. Tools of greater thickness must be treated several times according to the described procedure.

2- A mixture of 10 parts of natural resin - 5 parts of cod oil - 2 parts of tallow - is suitable for the regeneration of superheated steel tools.

Quench in greasy baths.

1. 150 grams of ordinary resin - 250 grams of fish oil - 125 grams of purified tallow. The resin is melted in the oil and the separately melted tallow is added.

2. 200 grams of cod oil - 150 grams of tallow - 110 grams of wax (Suitable for large pieces).

3. 500 grams of oil - 10 grams of paraffin.

4. 90 grams of fish oil - 200 grams of tallow - 25 grams of beeswax.

Quenching in glycerin.

For great hardness: glycerin with a density of 1.08 to 128 with the addition of 1 ... 496 potassium sulfate.

For soft tempering:

Glycerin of the same density, with the addition of 1 to 10% manganese chlorate or 1 ... 4% potassium chlorate Quench with mercury.

Because of its great conductivity, mercury produces a very sudden cooling, however, it heats much more quickly than water. In a heated state, mercury gives off very venomous vapors, which is why a large amount must be used, making the process very expensive. For this reason, mercury is only suitable for very small parts.

Avoiding oxidation in the tempering of metals.

In a container, boil a little water with 1 part of calcium chloride, then add 2 parts of fluoride. A viscous mass or paste is obtained. This mass is applied to the objects to be tempered. The surface of the parts thus treated is free of oxides after quenching. The oxidized spots, before tempering, appear without oxides, after tempering. The paste is removed after tempering, using a brush, cloth or washing.

COLORING OF METALS.

The natural color of metals can be changed using two different systems: the chemical system and the mechanical system.

CHEMICAL SYSTEM

The chemical coloring of metals consists of a process by which the surface of a metal is transformed into a metallic alloy, insoluble in water, with great adhesive power against the action of chemical substances. As examples for a natural coloring, the known oxide layers (tempering colors in most technical metals, which are produced by contact with air, can be used. Artificial coloring offers the possibility of producing different colors and thus covering the color itself metals.

Preliminary and after-treatment.

Objects must be cleaned thoroughly. It is important that the baths act evenly on surfaces, that is, that they are applied regularly, when it comes to painting processes. In immersion processes, the solution must be well revolved, so that all parts of the object have contact with the solution that will have uniform concentration and temperature.

Of great importance is also the treatment after staining. Colored objects must be well washed with water, to remove acid residues that remain in the pores, in the small cracks, etc. The drying is carried out by means of heated sawdust, free of resins. If necessary, the objects are dried in a dryer. After drying, the objects must be brushed.

In many cases, a protective layer is needed to protect the color against the corrosive influence of air, moisture, harmful gases or even fingers. Small objects are varnished or waxed. For this purpose, heat a little wax, applying it to the heated metal, using a brush. The waxed surface is then rubbed. You can also dissolve the wax with benzine or turpentine oil.

It should be borne in mind that due to the very small thickness of the coloring layer, its appearance and uniformity depend to a great degree on the quality of the metallic surface, on which it is produced. It is important if it was formed by casting, lamination or electrolysis. Electrolytic layers are extraordinarily suitable for chemical staining.

Cleaning the metal surface.

To make the metal surface purely metallic, all substances adhering to it must be removed. These substances are primarily oxide layers, which adhere to metals in the form of fixed layers, caused by contact with oxygen in the air or by smelting, and also by fatty substances (eg, oil, resin, etc.) ; caused by any previous treatment of metals or by hand contact. Due to their viscosity, these substances can also have the effect of binding means for dust and other particles.

The process to be employed will thus accommodate the property of each metal. In general, three different processes can be distinguished:

a) Degreasing.

b) Mechanical preparation.

c) Deoxidation.

Often two of these processes come together, and, in many cases, the three also, to a single process. It is evident that the metal parts must be protected after cleaning, against any alteration of the clean surface. For this reason, the objects are cleaned immediately before subjecting them to deoxidation or they are deposited in a solution of 5 g of tartar in a liter of water. The most important thing is that they no longer have any contact with human skin or fat.

Degreasing.

The metal surface must be degreased in all cases where a treatment with aqueous solutions is applied. In places with fatty layers, water does not adhere, and when applying electrolytic processes, these places are insulating. In both cases, the formation of spots is favored. After degreasing the parts cannot be touched by hand and precautionary measures must be taken to ensure perfect work, p. eg by placing them on wires or picking them up with wooden tongs. Small pieces can be passed through the baths in stone powder crockery containers, similar to domestic drains.

Degreasing by means of lime.

When the objects in the mechanical preparation have been treated with a mass of extinguished lime or a mixture of extinguished lime and soda, it is possible that they do not need any further degreasing. The aforementioned media easily absorb grease and oil. These substances, however, must be kept in tightly closed containers because they easily absorb carbonic acid from the air, thus losing much of its efficiency.

Soap solutions and soap extracts also act in a similar way. These solutions do not dissolve greases and oils, but absorb them in the form of emulsions.

Degreasing using grease solvents.

These are liquid substances capable of dissolving greases, oils, resins, etc., such as p. benzene, benzol, carbon tetrachloride, ethylene trichloride or ethylene perchloride. The first two are flammable, while the others are not. These, however, have a slightly narcotic effect. Therefore, inhalation of the vapors of these substances should be avoided.

Preferably, two or three containers of degreasing liquids are used. First, the piece is immersed in the container containing benzene already used, thus containing a certain amount of grease, but which is still sufficient for the first cleaning. Then proceed with purer benzine, and so on until the last container, which must contain clean and pure benzine. Benzene with impurities is still used for combustion.

Degreasing by boiling with bleach.

This process is the most frequent. It is based on immersing the parts in hot solutions of caustic soda or sodium carbonate. These substances have the property of completely dissolving greases, oils and organic resins, as well as fatty acids (stearic acid, oleic acid and olein) through chemical transformation into soaps, soluble in water. 

However, they have no effect on greases and mineral oils (petroleum jelly, paraffin, lubricating oil and cleaning oil). These substances are absorbed and therefore removed from the surface.

Iron, nickel, copper and silver objects are dipped for 1/4 to 1/2 hour in a boiling 10% soda bleach and then washed with mild water. Lead, zinc, tin and corresponding alloy objects would be attacked too much by soda bleach, so they are brushed with a 3% sodium carbonate solution, carefully observing the effect. Aluminum should not be boiled either in bleach or in a hot sodium carbonate solution, as it is strongly attacked by these substances. 5 ... 10% sodium carbonate solutions with the addition of 0.5 ... 1% potassium silicate are suitable for degreasing aluminum. These solutions are also applicable to objects of lead, zinc, tin and their alloys.

Electrolytic degreasing.

This applies with good results for metals that are not attacked by leachate. The process consists of the following: the pieces to be degreased as cathode are placed in a bath, composed of a part of caustic soda or sodium carbonate and 2 parts of caustic potash or potassium carbonate (together ca, 50 g) in 1 liter of water.

A small addition of potassium cyanide (ca. 2grams for each liter of water) is also often recommended. As an anode they serve iron sheets or the bath container itself, if made of iron. The bath is applied warm, graded to hot, and the tension is adjusted so that there is a strong gas development in the parts. By the action of the current, alkali in greater concentration is formed in the parts serving as a cathode, which transforms saponifiable greases into water-soluble soaps. A large part of the water is mechanically expelled by the hydrogen that forms in the cathode, so that even unsaponifiable fats and oils can be eliminated through this process.

The fat that has not been saponified, is floating on the surface of the bath and therefore it is necessary to remove this fat so that the pieces are not greasy again when they are removed from the bath. Electrolytic degreasing is especially suitable for small, large-scale parts with uniform surfaces.

Excessive degreasing can cause brittle precipitations in galvanizing. The degreasing process should not take more than 1.5 minutes at most.

Degreasing can be combined with a slight preliminary copper bath, adding a little copper and potassium cyanide (ca. 50 grams / liter) and working for a short time with a current intensity of 3 A / dm2 Poorly cleaned places are hereby visible.

MECHANICAL PREPARATION.

This preparation has the purpose of transforming the surface into a regularly rough or smooth state. This is achieved by grinding or polishing. Used for this purpose are grinding wheels, steel, brass or rope wire brushes, driven by hand or mechanically and whose effect can be increased by the application of powdered emery, of a more or less hard granulation (sand, pumice stone, emery or corundelite, etc.). Small parts manufactured on a large scale are prepared in rotating drums, in which a grinding material mixed with water is used. A very effective process is the use of jets of sand or emery, thrown on the piece by means of compressed air. The materials for grinding are distinguished by their hardness, as follows (in order of the degree of hardness):

Grinding and polishing

Grinding is started with a coarse granulation, gradually passing to a finer granulation. In general, the material for grinding is placed on wooden discs that can be coated with cardboard, leather or felt, or also, cork. The first grinding is carried out with no. 60 ... 80, fine grinding with grinding no. 00 and the finishing with number 000. Using wheels, they must be wetted with oil or grease. The shine can also be achieved with emery powder, wet with oil and applied with a rope brush.

For polishing, softer powders are used, of a much finer granulation, called polishing masses, such as Paris red, polishing red, Fuller earth, Vienna lime, chrome oxide (especially for tempered steel). These materials are prepared with water, grease or oil and applied to wooden discs covered with cloth, chamois, felt, or compressed cloth discs. These means are also used to renew the shine of metals. Soft metals (gold, silver, brass) can be polished using a smooth round tool. Sliding it strongly over the surface that is preliminarily wet with soap water.

Polishing in drums.

Small pieces of iron manufactured on a large scale are advantageously used in closed drums. Inclined axle drums are extraordinarily efficient. Polishing is carried out with a polishing paste composed of clay soil, free of sand, and water with a little soap powder. The drum must rotate with ca. 30 rot / min. This treatment lasts a few hours. Then follow the finish to obtain high gloss. This is done by treating the pieces, in another drum with polishing balls and so much soap water to cover 1 cm. above the pieces.

When it comes to hardened parts, wet polishing is replaced by dry polishing, with the parts being treated in an iron drum filled with leather scraps.

Cleaning of cast iron parts.

For cleaning cast iron parts, using the rotating drum, blast slag from blast furnaces can be used as a cleaning medium. When the slag grains become rounded, they are replaced, as the grains are effective only as long as they have sharp corners. In addition, the drum for preparing cast iron parts must be equipped with a few small holes so that fine powder that comes off the casting can escape. By this measure, the treatment time is reduced, since, otherwise, a part of the parts would be involved in this powder without being affected by the cleaning slags.

Polishing of brass parts, drawn or stamped.

The polishing tool is immersed in a mixture of ox bile and water, in a 1: 1 ratio.

Polishing paste for aluminum.

An extraordinarily suitable mixture for polishing aluminum consists of a part of stearin oil, a part of Fuller earth and 6 parts of silicic acid.

Recipes for polishing brass and bronze.

The). A well approved liquid is obtained with the following recipe: 1.5 kg of soda soap dissolves under heating in 44 grams of soft water (rain or condenser water).

In this ca. 40 ... 50 ° a mixture is prepared, cold, of 8 kg of olein - 1.5 kg of gasoline - 3 kg of alcohol. It is revolved until its uniform and complete mixture. To this composition, a mixture of 4 kg of technical ammonia (0.960) and 10 kg of water is added little by little and is continuously revolved, resulting in a cloudy emulsion. Finally, to this emulsion is the cleaning powder that consists of a part of a mixture of 8 kg of washed infusory earth (Fuller earth) and 20 kg of silica chalk.

b) 20 parts of chalk are mixed with 10 parts of olein and a solution of 3 parts of tartaric acid in 60 parts of water is added. This composition is finally mixed with 7 parts of ammonia (specific weight 0.91).

c) Cleaning oils are more efficient. To produce them, proceed as follows: Mix 30 parts of paraffin oil or petroleum jelly and 10 parts of gasoline with 1 parts of distilled olein, heating everything up to ca. 500. Then, for the saponification of the olein, a mixture of 6 parts of technical ammonia (0.960) and 10 parts of 96% denatured alcohol is added in a fine stream, continuously revolving, until a clarified solution is obtained.

With a part of this solution, 20 parts of silica chalk are mixed with 8 parts of white silica soil, well washed, until it forms a uniform paste that is then diluted with the rest of the solution. The smell of kerosene can be eliminated by adding amyl acetate, lemon oil or nitrobenzol.

DEOXIDATION (De-oxidation)

Under deoxidation, the processes used to chemically remove the oxide layers are understood. These layers are generally composed of oxides, hydroxides or carbonates of the metals themselves and are commonly soluble in diluted sulfuric acid, muriatic acid or nitric acid. The metals themselves are slightly attacked by these acids and, therefore, it takes a lot of skill to form the process once the oxide layer has been removed, and the metal surface is attacked as little as possible.

The duration of de-rusting depends mainly on the thickness and type of the oxide layer to be removed and, moreover, on the concentration and temperature of the acid. Also of influence are the salts produced during deoxidation and dissolved in the acid. Sulfates that are formed when sulfuric acid is used, delay the deoxidation process. This retarding influence is, however, less in deoxidation with muriatic acid, as the chlorides produced can accelerate the process (especially when it comes to iron).

The deoxidation containers must be made of wood, covered with lead, earthenware, stone powder dishes, natural stone or acid-resistant tiles.

Iron and steel de-rusting.

a) As a rule, remove the oxide layer, rust, iron bait, etc. by means of sulfuric or muriatic acid diluted by ca. 1 ... 5%. The time of action of the acid should be short, for the reasons mentioned above. A decrease in the action time is possible by increasing the temperature. After the acid treatment, the pieces are quickly washed, immersing them in a weak bleach of soda, lime water or in a solution of sodium carbonate, to neutralize any residues that may get stuck in the pores and, finally, wash them in clean water.

b) For cast iron. - Sulfuric acid of 1 ... 10%; for steel, 20% sulfuric acid. Other harder iron grades must be annealed or, better, annealed in an iron oxide or zinc oxide shell. As a mordant for the material to be galvanized, muriatic acid was better approved, due to its faster effect. In the tinplate industry, this acid is used at a high temperature, thus achieving a considerable decrease in the duration of deoxidation, compared to the use of sulfuric acid.

c) De-rusting by means of phosphoric acid. - This acid is capable of dissolving iron oxides and rust, but, being weak acid, it attacks the metallic iron very little, so that the addition of some other mordant is not necessary. In addition, this acid forms, on the iron surface, a thin layer of iron phosphate that adheres firmly to the metal, protecting it against new rust. Because of its rough quality, this layer guarantees an extraordinary adhesion capacity for paints with paints and varnishes. According to a well-tried process, iron is first treated in a 15% phosphoric acid bath to remove corrosion products. After that, the metal is washed with water, treating it again in a hot bath of 1 ... 2% phosphoric acid, at a temperature of 70 ... 809, for ca. from 10 ... 15 me. This process is very appropriate for all cases in which paints or enamel are subsequently applied. Deoxidation with sulfuric or muriatic acid must be avoided, due to the danger of rusting under the applied layers.

d). To whiten steel and iron objects, concentrated nitric acid (400 Bé) is used, to which a little soot is added.

e) Hydrofluoric acid attackers - Instead of sulfuric acid, hydrofluoric acid is also used, which dissolves not only sticky baits, but also the sand stuck to the mold. This striker consists of water with 1 ... 1.5% hydrofluoric acid. Hydrofluoric acid should be stored in wooden containers with or without lead coating. The outer side of the containers can advantageously have one or two asphalt varnish hands. To work with this acid it is recommended to use rubber gloves, attacking it, strongly, the skin and nails