The present patent application for industrial invention relates to a decoration process of a leather sheet. The field of reference is the processing of hides, and in particular of leather sheets.

As it is known, the decoration process of leather sheets provides for manually engraving a surface of the leather sheet.

In particular, it is necessary to print or reproduce on a paper sheet a drawing to be obtained on the surface of the leather sheet.

Then, the leather sheet is moistened, for example by spraying water on the surface of the leather sheet to be decorated, in such a way to soften the leather sheet.

The paper sheet with the drawing to be reproduced is placed on the surface of the leather sheet. The drawing is transferred on the surface of the leather sheet with a pencil or a stick.

The leather sheet is cut by hand with suitable cutters, following the drawing traced on the surface of the leather sheet, in order to permanently engrave the drawing on said surface. Different visual effects are obtained by varying the cutting speed, the cutting pressure or the length of each engraving.

Moreover, it is necessary to choose which parts of the drawing are to be engraved with higher strength, in order to be in bas-relief, and which parts of the drawing are to be engraved with lower strength, in such a way to be in high-relief.

The decoration process of a fabric sheet continues with the making of shades and the beveling of the drawing edges.

Although it permits to engrave a drawing on a surface of the leather sheet, such a decoration process of the leather sheet is impaired by several drawbacks. A first drawback of the process according to the prior art consists in the fact that such a decoration process of the leather sheet is a completely manual, time-consuming operation.

The manual processing of said leather sheet must be performed by specialized workers who are able to make the desired drawing on the leather sheet.

Several years of study and preparation are necessary in order to artistically reproduce the drawing on the surface of the leather sheet. For this reason, specialized workers are difficult to find. At the same time, being highly skilled, such workers may require a high remuneration, thus causing a high production cost of the decorated leather sheet.

Moreover, such a handicraft process produces a large quantity of waste because of the errors made by workers when engraving the surface of the leather sheet.

A second drawback of the decoration process of the leather sheet according to the prior art consists in the fact the series reproduction of the decorations on the leather sheet is impossible because of the manual engraving. Consequently, each leather sheet will be different from the others. In other words, it is not possible to automate the engraving of said leather sheets. In view of the above, the production time of each leather sheet is long with high production costs.

A third drawback of the decoration process of the leather sheet according to the prior art consists in the fact that the tools that are necessary to engrave the leather sheets are expensive and difficult to find.

It must be noted that, in addition to the aforementioned prior art, additional processes are known for the decoration of leather sheets, such as pressure-printing of objects, printing with steel decorated rollers, laser printing, engraving and/or carving.

US5853637 discloses a method of replicating images of animals or plants onto a leather support by means of plates or thermoplastic sheets. The purpose of the present invention is to remedy the drawbacks of the prior art by disclosing a decoration process of a leather sheet that is simple and rapid to make.

An additional purpose is to disclose a decoration process of a leather sheet that can be automated so as to permit the series production of leather sheets decorated with the same drawing.

A decoration process of a leather sheet according to the invention comprises the provision of a leather sheet, preferably a vegetable-tanned cow leather sheet. Said leather sheet has a thickness of at least 2 mm.

The process of the invention proceeds by providing 400-600 ml of water, preferably 500 ml of water, and 60-90 mg of caustic soda, preferably 70-80 mg, for each square meter of leather sheet.

Successively, the water and the caustic soda are poured in a container. The water and the caustic soda are mixed together in such a way to obtain a compound. More precisely, the water and the caustic soda are mixed together and are let to rest for at least 8 minutes, preferably 10 minutes, in such a way that the water and the caustic soda can form the compound.

The compound is homogeneously applied on a surface of the leather sheet with a brush.

The compound obtained by mixing 500 ml of water and 70-80 mg of caustic soda is sufficient to moisten a leather sheet with 1 square meter size.

The surface of the leather sheet absorbs the compound, softening and acquiring a darker color compared to the original one.

After completing the application of the compound on the surface of the leather sheet, it is necessary to wait for at least 2 minutes for the compound to penetrate the leather sheet.

The process of the invention continues by providing one or more objects with a shape to be imprinted on the leather. For instance, said objects may be leaves, wood, glass molds, etc. Preferably, said objects are provided with ribs. Said objects are placed on the moistened surface of the leather sheet. Optionally, wooden boards are positioned on said objects.

The leather sheet, the objects and the wooden boards are pressed together with a press at a pressure of 100-400 kg/sq m for at least 10 minutes; preferably, the applied pressure is 200-300 kg/sq m for 15 minutes.

In view of the above, the shape of the objects is impressed on the surface of the leather sheet, obtaining a decorated surface. In particular, if the objects are provided with ribs, said ribs will be impressed on the surface of the leather sheet in order to create a decorative pattern.

Successively, the wooden boards and the objects are removed from the leather sheet.

Optionally, 200-500 ml of hydrogen peroxide for each square meter of leather sheet is applied on the decorated surface of the leather sheet in order to enlighten the color of the decorated surface of the leather sheet and eliminate the compound from said surface.

Preferably, the amount of hydrogen peroxide that is necessary to enlighten a leather sheet of 1 square meter size is 300-400 ml.

Hydrogen peroxide with high volume must be used, preferably hydrogen peroxide with 120-130 volume, in order to enlighten the decorated surface of the leather sheet.

In particular, the hydrogen peroxide is distributed on the decorated surface of the leather sheets. Said decorated surface is rubbed with a cotton cloth to make the hydrogen peroxide penetrate the leather sheet.

If necessary, the application of hydrogen peroxide on the decorated surface of the leather sheet can be repeated several times in order to additionally enlighten said decorated surface.

The leather sheet is let to dry for approximately 24-48 hours. During such a period of time, the hydrogen peroxide penetrates the leather sheet and the enlightening of the decorated surface of the leather sheet continues. After such a period of time, the surface of the leather sheet achieves its final color. The advantages of the process of the invention are evident, in view of the fact that the decoration of the leather sheet is made with a press in such a way to impress the shape of the objects on the decorated surface of said sheet. Therefore no specialized workers are required to decorate the leather sheet. In this way, the decoration of leather sheets can be automated and accelerated. Consequently, the time needed for producing decorated leather sheets is reduced compared to the process of the prior art.

Moreover, the process of the invention allows for the series production of leather sheets that are all decorated in the same way.

The process according to the invention is more convenient than the process of the prior art because it does not require the manual work of specialized workers or the use of specific tools that are expensive and difficult to find.