FR2485761A1 - Method of multi colour printing on to monochrome base - involves using various media, e.g. paint or ink applied by spray or brush to specific areas - Google Patents

Abstract

The system for making polychrome pictures consists of depositing on aligned monochrome documents, corresponding to the original take, a substance such as paint, ink or similar. These are then printed to form the various multi coloured shades. The values of the paint or ink follow pre-established ranges with known keys. This gives repetition in both time and space. The values are applied to the desired parts following the appropriate methods for each, e.g. by brushes, rollers or by spraying.

Description

 The present invention relates to a method making it possible to produce polychrome prints in two, three, four or more colors, without implementing the techniques of "color photoengravings" usually used.

 The present invention allows these print jobs to be carried out under optimal conditions of efficiency and economy.

 In the current state of knowledge, the realization of a polychrome printing can be carried out according to several methods whatever the mode of printing chosen (collotype, lithography or offset, typography, heliography, serigraphy).

 A first known prior technique is to print using as many ink colors as there are tones in the base document. So you need as much printing material and as many runs on the machine as there are colors to reproduce. This method is therefore only valid for prints with a limited number of colors.

 A second known prior technique consists in reproducing all the colors of the document using only three primary inks which are yellow, magenta red and cyan blue (three-color) and possibly adding a black to modify or reinforce the nuances obtained ( four-color).

 A preparatory phase (photogravure in tri or four-color process) consists in "analyzing" the basic document in order to determine the values in which the primary inks will have to be printed at a given point, to obtain at this point a color conforming to that of the initial document .

 This analysis, called "selection", is generally carried out from an execution document in color or from an ektachrome. It is performed either by conventional methods or by electronic methods.

It should be noted that in the case of standard printing on paper, the primary inks marketed by various manufacturers have identical chromatic characteristics (unified European range).

Another known prior art called "weft of
Benday "consists of mounting mechanical screens of various values to compose the printing element of each primary ink.

 This method is valid for making tones coming in solid color "in simple geometrical forms but cannot be applied to detailed documents because it involves in this case complex montages difficult to achieve and much more expensive than photoengraving in tri or four-color process.

 The method according to the invention makes it possible to produce several hundred compound colors coming either in solid color or in "values" or "models" and applies more particularly to reproductions of artistic creations (decorative compositions, illustrations, posters and posters, material advertising or packaging, etc.).

 The method according to the invention consists in replacing the color execution document (which in the second known prior technique would be intended for photoengraving operations in tri or four-color process) by two, three, four (or possibly more) monochrome documents in registration painted in a shades of various values chosen from pre-established ranges according to various basic combinations.

The process can be summarized as follows
a / Establishment of a fine and precise layout delimiting the zones or patterns corresponding to the various composite shades desired by the artist.

- Placement, in the margins, of "spotting swallows",
- By way of nonlimiting example, this drawing can be done in black India ink either on a transparent or translucent support such as acetate or kodatrace, or on an opaque support such as card or paper grain-free design.

 b / Duplication of this layout in as many copies as the printing ink colors were chosen to obtain the multiple tones composed of the initial model, for example three for a tri-chromium print, four for a four-color printing or more if it has been decided to use additional colors such as, for example, a bistre or any other color.

 Duplication must be carried out on a rigorously stable support which is not likely to undergo dimensional variations as a result of atmospheric conditions or the humidity of the inks or paints used thereafter.

 This support can be in any material offering the desired guarantees of stability.

 For example, a paper; drawing pasted on a thin metal plate is an excellent support.

 Any known duplication process can be used as long as it scrupulously respects the initial design and or all the copies obtained will be strictly identical.

 c / Notation, in the margin of each of the copies thus duplicated, of the color of printing ink. For example, for a four-color print, we will have a copy for yellow, one for magenta, one for cyan and one for black.

 d / Determination, by means of the "keys" given by the pre-established range, of the various values in which the printing inks must come to compose the various nuances desired by the initial model.

For example, in the case of a four-color print plus a bistre or a print in five colors, shades x, y, z of a model comprising 27 different shades could be composed as follows
Yellow Maqenta Cyan Black Bistre
x = 10% 90% 60% -
y = - 30, '- - 75,'
z = 40% 15% 80% 5, '
e / Application, on each document, of the various values desired by the determination indicated in point d, by means of a paint or an ink of one and the same color but degraded either by addition of white, or by dilution for range from 100% to 0% via the intermediate values provided for by the preset range.

 The painting of each document can range from pure black to pure white, passing through all kinds of gray values, but other colors can be chosen to establish degraded values.

Thus, it has been observed that the use of pure vermilion red ranging from pure white to a range of roses gives good results for establishing the imitation mentioned in point "f".

 It should be noted that using a white support, it is not necessary to paint the areas in which no value of the treated color enters.

Thus, in the example given to the pant "d" all the zones corresponding to the shade x will remain blank on the documents of black and bistre. All areas corresponding to the shade will remain blank on the documents of yellow, cyan and black etc.
f / Engraving in "imitation", as for a simple black drawing of each of the documents thus obtained, but by orienting the axis of the frames as it is normally practiced for work in polychromy.

 It has been observed that the orientation of the screens is not necessary for "transfer printing" since, by sublimating in order to be fixed in the fabric, the dyes contained in the transfer inks and deposited on the temporary support that constitutes the printing paper, act as a "dye" and do not need "optical illusion" to create the compound color.

 The method according to the invention therefore consists in carrying out itself, directly on monochrome documents, the selection of the various values in which each of the basic inks (primary or non-primary) chosen for the printing, will have to be printed, in such or such part of the total surface, to reproduce the various nuances of the polychrome print.

 The method according to the invention is characterized in that the establishment of the components of the final shades, selected from one or more ranges, the keys of which have been established (as is the case with a known prior technique called " Trame de Benday ") is operated not by mounting mechanical wefts (the use of which offers no flexibility and is limited to surfaces that are not very detailed) but by the application of paints or inks corresponding to very defined values. The application of these paints or inks can be carried out according to all kinds of methods (paintbrush, brush, pouch, roller, pad, airbrush, etc.) from which one will choose the best suited to the specific case of the work to be produced.

 In the case of a very detailed document, the brush will allow for example to achieve extreme finesse.

 The method according to the invention makes it possible not only to produce "solid colors" but also degraded tones by enhancing or decreasing the value of one of the components. In this area, the artist may possibly produce his documents himself or touch them up to create personal "effects".

 The process according to the invention is not limiting as regards the "Values" which can be used. Mixtures or dilutions of paints or inks can lead to numerous degradations, but it has been observed that it is preferable for the sake of efficiency and saving, to limit the number; for example 6 values make it possible to obtain 342 shades for a print in 3 colors.

 Of course, the number of shades that can be distinguished from each other is less than the number of combinations that we obtain with the formula (n + l) x - 1 in which n = the number of values and x = the number of basic colors of the print because the low values of light colors do not significantly modify the strong values of dark colors.

 The paints or inks of various values used to execute the monochrome documents must be prepared in the laboratory, according to precise dosages so that each value remains strictly uniform to that used for the establishment of the basic range.

 The method according to the invention allows great flexibility of use because the artist executing the documents can, if he wishes, modify a tone of the preset range by mixing two values produced by the laboratory. This modification will thus remain within the limits of a known range. As an example, let us cite two shades, x, y, of the preset range likely to suit a designer who would however like to obtain a tone a little redder than x and a little less red than y. Assuming that the red component of x is a value "c" and that of y is a value "d" it will be enough, when painting the document provided for the drawing of red, to mix the values c and d, to obtain a intermediate value.

 The modification of a shade of the basic range by mixing two known values of one of the components will allow either to realize solid colors of a new shade, or to create the "Ot" effects modeled mentioned above.

 The application of the method according to the invention is particularly advantageous in the field of polychrome printing intended for transfer by sublimation.

 In fact, the transferable inks offered by all manufacturers, both in France and abroad, are not standardized, i.e. their chromatic characteristics do not correspond to the G.U.E. (By way of example, there is no sublimable dye allowing cyan to be produced).

 The three or four-color photogravure processes usually used for traditional prints are therefore # unsuitable for selections for transfer. Consequently, the results are approximate and require long and costly corrections.

 The method according to the invention makes it possible to eliminate the randomness of the selection since it is carried out, using the keys of a basic range, with paints whose precise values are the tested and recognized components of the shades previously calibrated.

 The method according to the invention makes it possible to obtain good conformity and good reproducibility of the nuances of the basic range provided that the various parameters relating to printing and to the subsequent transfer operations are respected.

Claims (5)

 1. A process intended for producing polychrome prints, essentially characterized in that it consists in depositing on monochrome documents for registration, each of which corresponds to one of the basic colors of the print, a substance (paint, ink or analog), depending on the values in which these basic inks, primary or non-primary, should be printed to compose the various shades of polychromy.  2. Next process (1) in which the values of the ink paint or the like correspond to a pre-established range or to several pre-established ranges, the keys of which are known and allow repetition in time and in space.  3. Method according to any one of the preceding claims, in which the said values are applied to the desired places, according to the method best suited to each specific case, for example, by means of brushes, brushes, pouches, buffer rollers or the like, or by means of an airbrush.  4. Method according to any one of the preceding claims, characterized in that the documents painted in various values do not need to undergo selection of photoengraving in tri or four-color process but are only engraved in imitation as for a simple black print .  5. As new industrial products, all polychrome prints in normal inks, all polychrome prints in transfer inks and all articles manufactured with transfer prints produced in accordance with the process according to any one of the preceding claims.