FR2782025A1 - Process for the in-depth coloration of a hard rock substrate, such as granite, comprises the application of a saturated silver nitrate solution containing a dye and color development by exposure to UV radiation - Google Patents

Abstract

The process enables an in-depth coloration of a natural rock substrate, in particular of granite for which no adequate technique has hitherto been found. The process is effected in four stages: (i) Preparation of the surface to be colored by degreasing; (ii) application of a solution of silver nitrate containing at least one dye; (iii) development of the color by exposure of the treated surface to UV radiation; and (iv) cleaning of the treated surface.

Description

- i -

  DEEP COLORING PROCESS FOR THE SURFACE OF A

  SUBSTRATE IN NATURAL ROCK, SUCH AS GRANITE.

  The present invention relates to the field of deep coloring of the surface of a hard material and more particularly of natural rock substrates,

  for decoration and protection purposes.

  These natural rock substrates will be conventionally called "substrates" in the context

of the present invention.

  The Applicant has in fact noted the absence of a reliable coloring process for a natural rock substrate such as granite. This absence is of course due to the very composition of the granite, crystalline rock formed from a heterogeneous mixture of quartz, feldspar and biotite, but also, to the fact that no one has hitherto found an adequate process for producing

  deep coloring of the granite.

  This absence poses problems as to the number of colors proposed by the decorators who are necessarily limited to the natural colors offered by the extraction of said rocks. In addition, these rocks often resulting from volcanic eruptions have a natural color matching the surrounding geographic region where a

  preponderant transport cost in the cost price-

  to offer for sale a wider range of natural colors. To respond to an increasingly demanding clientele in the diversity of colors of construction elements made in this type of hard material for floor appearance coatings or facade cladding or for street furniture or kitchen (worktops), suppliers are forced to feed from several extraction zones spread in many countries such as France, Italy, Africa, Brazil, America, etc. .. On the basis of these observations, the Applicant has conducted research which has led to the development of an original process for treating substrates in natural rock such as granite, the primary objective of which is to make the deep coloring of said substrates more reliable. coating or ornamental purposes so that it can guarantee a correct lifespan and, as a second objective, to obtain from the results achieved, the increased protection of the state of surface of

substrates so colored.

  According to the main characteristic of the invention, this process for coloring a substrate in natural rock such as granite is remarkable in that it consists: - firstly, in preparing the surface condition of the substrate to be colored , for example by applying an alcohol-based solution to obtain a degreasing of said surface condition, - in a second step, to be applied to the surface of said substrate which has just been prepared, a nitrate-based coloring solution silver added to at least one dye, - in a third step, to reveal the color of said substrate by exposing the face of the latter impregnated with the coloring solution, to ultraviolet rays until the coloring solution dries, - and in a fourth and final step, to clean, preferably with water, the surface condition of the substrate

just being colored.

  This coloring process is particularly advantageous in that it uses a vehicle (silver nitrate) of the dye which has the purpose of authorizing, in a first step, the deep penetration of the thickness of the substrate by a natural migratory movement and this, according to the absorptivity coefficient admitted by the very composition of the substrate material, and in a second step, the fixing of the color of the thickness of material thus impregnated by simple exposure to ultraviolet rays which can be natural, such as rays from the sun. Thus, a simple exposure to the day is enough to reveal the color of the thickness of the substrate which has just been impregnated with the coloring solution. Although the impregnation of the coloring solution can be obtained by a natural migratory movement, it will be easy to force this movement of penetration by industrial techniques

  commonly used in this field.

  The Applicant has successfully applied its coloring process with the support material, granite, by simple application and by natural exposure to the sun's rays. She noticed that when she preferably used a saturated silver nitrate coloring solution which consists of dissolving by heating one kilogram of silver for two liters of acid

  nitric, the coloring was of better quality.

  This method of coloring a substrate in natural rock such as the granite according to the invention offers another great advantage insofar as the various stages can be obtained by industrial techniques which are particularly indicated for a large-scale coloring treatment. However, although the process of the invention is intended for industrial purposes, the use of this type of coloring has the advantage of allowing manual coloring of a substrate such as granite, by simple application of the solution of coloring with a brush and by simple exposure to the natural rays of the sun, of the material

thus permeated.

  According to a first embodiment of the process of the invention, the dye of the coloring solution can be previously diluted in the saturated silver nitrate solution before application. This preparation will preferably be chosen in the case of coloring in

large series called industrial.

  According to a second embodiment of the process of the invention, the dye of the coloring solution can be previously deposited on the surface of said substrate before the application of the saturated silver nitrate solution. This preparation will preferably be chosen in the case of coloring in a small series called artisanal which allows, from a neutral solution of saturated silver nitrate, to use different

dyes.

  Another advantage in using the coloring process of the invention lies in the better use of the products extracted from quarries. Thus, for example, for granite, many rock falls not exploited for various reasons (defect, bad grain, small size) are available and ready to be used for such a process which will give back to said

  falls a new shine to their surface state.

  The coloring process of the invention can be preceded by certain steps for preparing the surface state of the substrate, namely for granite, polishing which ensures perfect flatness of the surface state of the support material. The preparation of the support material can also be carried out by etching,

sandblasting or excavation, etc ...

  This process is, moreover, particularly advantageous in that it makes it possible to envisage several kinds of coloring for which the staying power and the quality of the coating could not hitherto be guaranteed. Of course, the shade of the color will be chosen according to the grain and the color of the substrate material in order to standardize the appearance of the surface on which it has been

  applied the coloring solution according to the invention.

  In the case where the substrate material consists of granite which is a grainy rock, the dye of the coloring solution will respect the characteristic grain of the latter so that some of its constituent elements, namely Mica, Quartz and Feldspar

can be identified.

  Thus, the Applicant has successfully applied to granite, as a coloring agent, a coloring solution based on saturated silver nitrate, methylene blue, malachite green, eosin, fuchsin, rutin, bright green, vitamin B2, buttery yellow,

riboflorin.

  It is nevertheless understood that the process for coloring a substrate in natural rock such as granite, which has just been described above, was done for the purpose of disclosure rather than limitation. Of course, various arrangements, modifications and improvements could be made to the above example, without departing from the scope of the invention taken in its

  wider aspects and in his mind.

  The process should not be limited to the material but could be considered for any type of material. So, for example, in an imagined variant

  by the Applicant, the substrate will be marble.

- 6 -

Claims (18)

  1. Process for deep coloring of the surface of a substrate in natural rock, CHARACTERIZED IN THAT it consists: - firstly, in preparing the surface condition of the substrate to be colored, - secondly, to be applied to the surface of said substrate which has just been prepared, a coloring solution based on silver nitrate added to at least one dye, - in a third step, to reveal the color of said substrate by exposing the face of the latter impregnated with the coloring solution, with ultraviolet rays until the coloring solution has dried, - and in a fourth and final step, to be cleaned   the surface condition of the substrate which has just been colored.   2. The coloring method according to claim 1, CHARACTERIZED IN THAT the coloring solution is a   saturated silver nitrate solution.   3. A coloring method according to claim 1, CHARACTERIZED IN THAT the dye of the coloring solution is previously diluted in the solution of   saturated silver nitrate before application.   4. The coloring method according to claim 1, CHARACTERIZED IN THAT the dye of the coloring solution is previously deposited on the surface of said substrate before the application of the nitrate solution. of saturated silver.   5. A coloring method according to claim 1, CHARACTERIZED IN THAT the preparation of the surface condition of the substrate to be colored consists of degreasing by   application of an alcohol-based solution.   6. The coloring method according to claim 1, CHARACTERIZED IN THAT the surface condition of the substrate coming   to be colored is cleaned with water.   7. The coloring method according to claim 1, CHARACTERIZED IN THAT the color of said substrate is revealed by exposure to sunlight until drying of the coloring solution.   8. A coloring method according to claim 2, CHARACTERIZED IN THAT the preparation of the coloring solution in saturated silver nitrate consists of dissolving by heating one kilogram of silver per two liters nitric acid.   9. A coloring method according to any one of   claims 1 to 8, CHARACTERIZED IN THAT the dye of   the coloring solution consists of methylene blue. 10. A coloring method according to any one of   claims 1 to 8, CHARACTERIZED IN THAT the dye of   the coloring solution consists of malachite green. 11. A coloring method according to any one of   claims 1 to 8, CHARACTERIZED IN THAT the dye of   the staining solution consists of eosin.   12. Coloring method according to any one of   claims 1 to 8, CHARACTERIZED IN THAT the dye of   the coloring solution consists of fuchsin. 13. A coloring method according to any one of   claims 1 to 8, CHARACTERIZED IN THAT the dye of   the coloring solution consists of rutin.   14. Coloring method according to any one of   claims 1 to 8, CHARACTERIZED IN THAT the dye of   the coloring solution consists of green brilliant.   15. A coloring method according to any one of   claims 1 to 8, CHARACTERIZED IN THAT the dye of   the coloring solution consists of vitamin B2. 16. A coloring method according to any one of   claims 1 to 8, CHARACTERIZED IN THAT the dye of - 8 -   the coloring solution consists of yellow butter. 17. A coloring method according to any one of   claims 1 to 8, CHARACTERIZED IN THAT the dye of   the coloring solution consists of riboflorin. 18. Substrate in natural rock colored by the process   coloring according to any one of claims 1   at 17, CHARACTERIZED BY THE FACT that it consists of granite.