Aluminum etching at home

The etching of aluminum (products from this metal) is carried out in order to clean its surface from the top, unnecessary layer or from rust. There is also such a variety - artistic etching, when it is necessary to engrave the drawing on the surface of the metal part.

Types of etching

The etching of metals in general and aluminum in particular is of two main types: chemical and galvanic. The last method is just artistic.

In the case of a chemical: the product is placed in a container in which a solution of hydrochloric or sulfuric acid is pre-poured. In the same way, the aluminum billet is etched with alkali, for example caustic soda.

A galvanic (otherwise - electrolytic or electrochemical) is due to the electric battery. The process itself is carried out in a special bath, where there is an anode and a cathode.

Next, each of the methods for etching aluminum will be discussed in more detail. Also find out which method is the safest at home.

Etching of aluminum with acid

In view of the fact that very strong acids are used in this process, first of all it is necessary to observe increased precautions when working with them. The operator should wear gloves, a mask, an apron. It is important that the room where the process itself takes place is well ventilated. Not having certain skills and without certain protective equipment to work with acids is not recommended.

As already noted above, the aluminum product is placed in a container with an acid. Most often, when chemical etching of aluminum, acid uses the following reagents: hydrochloric acid or sulfuric acid. When they interact with the metal, hydrogen is released. Outwardly it looks like this: the surface of the product is covered with small bubbles. But, in principle, this can be prevented if you add a special ingredient to the tank in advance. Thus, the metal will be protected from bubbles by the thinnest film.

A very important point: all operations for etching the product from aluminum with acid must be carried out intensively, so that the surface of the metal itself remains intact.

The described method is recommended to be carried out in containers made of wood or concrete. At the same time, the inner surface of it should be lined with acid-resistant tiles so that the walls of the container do not corrode.

This method is not used in practice very often.

Aluminum etching

Most often, this method uses an aqueous solution of sodium hydroxide (a variant with or without additives is possible).

And it is used to clean the surface of an aluminum product from oxide or unnecessary grease and to get a smoother (matte or glossy) surface.

Why do you need to clean it up so thoroughly? To ensure that the finished product (for example, decorative architectural elements, plaques) had an ideal surface. And also this method is used for deep engraving.

The method of pickling alkali aluminum, on the one hand, is quite inexpensive, but it is very laborious.

Features of this method

The solutions used contain from four to ten percent sodium. The temperature during etching with alkali is about 40-90 degrees Celsius.

If necessary, to get a light foamy coating on the workpiece, apply a moisturizer or special additive.

The average temperature in the midst of the process is sixty degrees. It is at such thermal values that a qualitative cleaning of the surface occurs.

Optimal purity of aluminum is 99.5%, and the concentration of sodium hydroxide solution is 10, 15, or 20%.

Thus, during the reaction, aluminum dissolves in caustic soda, while hydrogen is released. As a result, a composite aluminate is formed, and it exists only in the alkali solution.

Further processes occurring during pickling with alkali

During this process, gradually the amount of caustic soda becomes smaller. And thus the speed of the process itself decreases, but the viscosity increases.

Assuming that no caustic soda is added at all, the reaction can be very slow. But as a result, a brownish or pure solution for etching aluminum becomes white.

And from this moment the speed of the process increases.

As a result of the reaction, alumina hydrate precipitates into the precipitate, which looks like a suspension. And also there is a caustic soda, which is also necessary for the etching process to continue.

Results for the method in question

It has been experimentally observed that a solution of caustic soda with intensive use in the process of etching begins to "absorb" aluminum. And this happens until the amount of caustic soda is reduced to one-fourth of the original volume. And after that the process will continue with a free, caustic soda that fluctuates in its quantity. And this, in turn, depends on the temperature, frequency of use and intensity of stops (pauses).

In this case, the hydrate slowly sinks or forms crystals at the bottom and / or sides of the container. The resulting hydrate will be quite dense, and removing it will not be easy. Sometimes he just strives to settle right on the surface of the heating coils.

There is another important point that concerns the aluminum content. During the etching of products from this metal in caustic soda, it is necessary to strictly observe the ratio of the amount of aluminum and soda. Because the more aluminum, the slower the process will be. From the point of view of practice, it becomes clear that it is necessary to constantly increase the amount of caustic soda as the amount of aluminum in the container increases.

Thus, the process of etching aluminum with alkali can be continued all the time. A loss of caustic soda will occur only because of its entrainment with steam.

This method is really applicable from the point of view of practice. But there are several nuances that you should not forget: from time to time, remove the hardened hydrate sediment; Clean the filter; Remember that the capacity in which the process is carried out, with its constant use, can serve no more than two years.

And in the rest, there were no complications concerning the use of this method.

Subsequently, after chemical etching of the aluminum billet, its surface must be thoroughly washed, neutralized and clarified with a 15-20% nitric acid solution. This process is called pickling.

Galvanic method

The second method of etching is galvanic. It is simpler and more time-consuming. As a result, a very high-quality surface of the product is obtained, clear contours of the drawing (in the artistic mode, as galvanic varieties).

The peculiarity of this method is that it uses a source of electrical energy (4-5 V).

You will also need a bath of this size to fit a piece of aluminum. The material from which the bath is made must be a dielectric. The composition of the bath for etching aluminum is a solution of copper sulfate and table salt.

Before starting the process, the workpiece must be cleaned and also degreased. Then solder the copper wire to the product and dip it into a solution of caustic soda, and then into a solution of sulfuric acid. After 2 minutes, remove and rinse under a stream of hot water. It is forbidden at this time to touch the product with your hands.

If some parts of the billet are not to be etched, they are applied with mastic. After that, you can start the process itself.

In this method, two so-called supports are used, which must be connected to the anode (positive charge) and cathode (negative) of the electric power source. It is important that these supports are located across the bath. An aluminum workpiece is attached to the support with an anode, and the workpiece is made of another metal on the second.

All this is lowered into the bath and held for a certain amount of time. After that, it is washed with turpentine and further processed by grinding and polishing.

Art etching

This type of galvanic method is quite popular at the present time. With its help you can make author's drawings, engraving, art prints, ornaments on any piece of metal.

And the result is a very clear, beautiful drawing. So to say, the author's work, which you can leave to yourself or give.

The original image can be painted on its own or printed (using a laser printer) on paper. Then stick the tape on the surface and wash the paper with hot water. As a result, the image should remain on the scotch tape. Leave to dry. Meanwhile, it is necessary to prepare the surface of the metal, on which the pattern will be applied - degrease it with alcohol.

Then glue the scotch with the pattern on the surface of the workpiece, while letting air bubbles out from under it. It removes excess glue and all unnecessary except the image itself.

Etching is carried out in the manner that has already been described above - galvanic.

Attention: with this process there is a possibility of releasing harmful gases, so people should leave the room.

Thus, aluminum etching at home is quite feasible. Only it is absolutely necessary to carry out all the important precautions!