Black engraving

This method is used to make the image engraved on metal more contrast. This method is mainly used for engraving silver products. When engraving for blackening, recesses are made with the help of engravers and chisels with a depth of 0.3-0.5 mm, and then the final processing of the drawing is carried out - the lines are aligned and the corners are cut. To do this, use all types of engravers, depending on the specifics of the pattern. So, straight thickened lines of letters in a handwritten font, which is most often used for engraving under blackening, are engraved with a bolt-stencil or a flach-scribe. The roundings of the letters are engraved only with a bolt engraver, and thin lines with a stencil. Everything that has been said about the engraving of a font applies to the engraving of a picture.

At the end of the engraving, the drawing is blackened. For this, all kinds of mastics and paints are used, but the simplest blackening is considered to be filling engraved lines with dark brown or black sealing wax.

Depending on the complexity of the pattern and the type of surface, one of the following blackening methods is selected. You can fill the recesses of the pattern with crushed sealing wax, after which the metal product is heated. The melted sealing wax fills all the recesses of the engraving, and its excess is removed with a metal ruler or spatula.

If the shape of the engraved product differs significantly from flat, another method is used. The metal is heated and sealing wax is applied to it. As it melts, the sealing wax fills the engraved grooves. When all of them are filled to the end, the excess sealing wax (while it has not yet lost its plasticity) is removed from the metal surface with a steel spatula or palette knife.

Upon completion of the blackening, the metal surface contaminated with sealing wax must be sanded again and polished to a shine, this time - finally. However, after such processing, the smallest particles of metal will stick to the sealing wax that filled the engraved grooves. From this, the drawing will become matte and will appear dirty. To restore the shine of sealing wax, the metal is heated again. As a result, the smallest metal particles will settle to the bottom of the engraved grooves, and the top layer of sealing wax will acquire a shine and a deep black tone.

This is the blackening process in general. Let us now consider old and modern niello recipes and methods for processing products.

Caucasian niello (from old recipes) consists of “1 spool of 84 silver, ? pounds of sulfur, 6 spools of red copper and 7 spools of lead. The alloy is poured onto a cast-iron or stone slab and, after cooling, is crushed, washed in water and dried. The powder is ready to use. When coating with niello, it is necessary to prepare a dough from 90% niello powder and 10% borax solution and fill the recesses on the product with this composition, then put it in the furnace to heat and melt the niello. After coating, the product is removed, cooled and polished.

In Germany, masters prefer this method of blackening: a small amount of borax is added to 1 part of silver and 2 parts of copper. In a steel crucible, 3 parts of lead are melted to add it to an alloy of silver and copper. Liquid lead is slowly poured into the silver-copper alloy and mixed well. A high crucible is filled up to half with yellow powdered sulfur and heated: 1.2–1.5 parts of sulfur (by volume) are taken for 1 part of the alloy. The resulting ternary alloy is poured into heated sulfur powder with constant stirring. The crucible is kept warm so that the mixture does not solidify. Sulfur partially burns out, it must then be added to the composition. Vigorous stirring achieves a good interaction of the parts, due to which silver and copper form a black compound with sulfur, which is poured into water. The resulting black should be hard and brittle, like glass. If its pieces can still be bent, then it should be melted again, however, it must be remembered that excessive heating or too long a stay in the furnace can lead to sulfur burning out. Then, ammonium chloride powder is dissolved in hot distilled water, which serves as a flux. It is added to pieces of niello and the mixture is ground in a porcelain mortar in the required amount, since only fresh ammonium chloride porridge can be applied to the product.

Another way is to first prepare silver sulfide, copper sulfide and lead sulfide separately, and then fuse them together.

To prepare silver sulfide for 97.8 g of pure silver in the form of crushed shavings, 20 g of sulfur in powder are taken, they are mixed and gradually heated in a graphite crucible to 300–400 ° C. Sulfur diffuses into the metal and forms silver sulfide. Copper sulfide and lead sulfide are obtained in the same way. For this, 250 g of sulfur are taken for 800 g of copper, and 75 g of sulfur for 400 g of lead. The resulting sulfur compounds are crushed and mixed in the following weight ratios: silver sulfide - 111.2 g, copper sulfide - 466.6 and lead sulfide - 422.2 g. The result is 1 kg of black, which is poured into a cold graphite crucible, poured on top dry charcoal and placed in a muffle furnace, heated to 800 ° C and after 30–40 minutes, when the black in the crucible is heated to 600–650 ° C, ammonium chloride is added to the crucible at the rate of 284 g of ammonium per 1 kg of black. Then the crucible is closed with a graphite lid and, after complete melting, the black is poured into an iron mold heated to 300 °C, in which the alloy slowly cools. There are other recipes for the preparation of niello, in which ammonium chloride, potash with table salt and borax are used as a flux.

There are two ways to apply niello - dry and wet. The dry method consists in the fact that the surface to be blackened is moistened with an aqueous solution of potash, borax and table salt, and finely ground black powder sifted through a sieve is poured onto it; then the product is carefully dried. In this form, the product enters the firing, which is carried out in muffle furnaces at a temperature of 300-400 ° C. The wet method differs in that the black is applied to the product in the form of a creamy slurry diluted with water. It is very important that the recesses are clean and free of grease. Raw fine-powder mixture of black, diluted in ammonium chloride solution, is applied with a brush or spatula into the recesses. The mixture is placed as thickly as possible and lightly tamped with a spatula. Recesses must be filled to the brim; with thin engraved drawings, the entire surface should be covered with a black mixture. The workpiece is dried for some time; as soon as the water evaporates, it is pushed into the furnace, and when the niello is melted and all the recesses are filled, it is removed from the furnace. It must be remembered that when reheating, sulfur particles burn out, the layer becomes porous and spots appear on it. Small volumes of ink can be melted with a soldering iron. In this case, it is necessary to concentrate the influx of heat on the base metal, heating it from the reverse side. When the mass melts, the heating is stopped. If the molten black does not fill all the recesses, add the required amount and heat again.

Artistic blackening Blackening is the decoration of silver and gold items with niello drawings, which in appearance resemble black enamel. Drawings are ornamental and plot. Niello is an ancient way of decorating artistic metals -

Today, such a service as laser engraving is very popular, as it allows you to apply various inscriptions and drawings on almost all types of materials. As one of the varieties of this type of work in our workshop in Moscow, you can order engraving with blackening. It involves a slightly different algorithm for applying images, and also makes it possible to get a more interesting end result.

Black engraving can be applied to various types of metals, wood and glass. It can be jewelry or other types of jewelry, phones, laptops, key chains, lighters, pens and any other souvenirs. In this case, you can use sketches of any complexity - from inscriptions and logos to full-fledged drawings. The master transfers the sketch provided in electronic form to the desired product and performs the work with the help of a special laser.

How is the engraved pattern blackened?

In order to engrave with blackening, two methods can be used - chemical and mechanical. They differ in the materials used and the algorithm itself.

Engraving with blackening by a chemical method is carried out as follows:

• with a special laser, the master engraves the necessary ornament on the product;
• after completion of work, a special chemical solution is applied to the drawing, which reacts with the material in those places where the engraving is applied;
• after the desired places turn black, the remnants of the substance are wiped off with a damp cloth.

A prerequisite for a qualitative result with such engraving is the speed of applying a chemical solution. It can act no later than 15 minutes after the end of work.

It is also very important to take into account all the features of the material that the master takes to work. There are certain metals and alloys that are not affected by the chemical, or may darken completely when exposed to it, losing their attractive appearance. These products must be handled with great care.

If the material does not lend itself to chemical blackening, its mechanical version is applied to it. Such engraving with blackening involves the use of several laser modes. As a result, the engraving depth is different, and therefore the color can be achieved darker. The cost of this service is calculated based on the size of the image that is applied, as well as the characteristics of the material from which the product taken into work consists.

Advantages of ordering laser engraving with blackening in our workshop

How the product will look after applying text or drawing to it with a laser depends entirely on the quality and accuracy of the equipment used. In our workshop, we work exclusively on the latest technologies, using modern and most accurate lasers. Our masters will cope with the task of any complexity in the shortest possible time. The price of our services will not hit your budget.

You can also place a bulk order with us, which will save you a lot of money. This service option will be the best choice in the manufacture of corporate or souvenir branded products.

Blackening engraving is a great way to transform a piece of jewelry or a gadget, mark a significant date or event, or add symbolism to a gift. In any case, the specialists of our workshop in Moscow will cope with their task perfectly, delighting you with the end result.