GB2043537A - Offset screen printing - Google Patents

Abstract

A design in colour is applied by screen-printing to an intermediate surface, and the design transferred from the surface to an article by a deformable transfer pad (30). In a repetitive process, the intermediate surface for each cycle of operations is free from residual colour left over from a previous cycle. The intermediate surface may be constituted by a roll of paper (92) which is advanced to present a fresh area for the application of colour in each cycle. Alternatively the intermediate surface may be a highly finished flat surface of a metal plate scraped free of residual colour, in each cycle, by a blade. The process is particularly applicable to the decorating of ceramic ware. <IMAGE>

Description

SPECIFICATION Printing ceramic ware This invention is concerned with improvements in or relating to printing, and more especially with off-set screen-printing machines for decorating articles of ceramic ware.

Screen-printing machines have been introduced into the ceramic ware industry for decorating articles of tableware, both flatware and holloware, by the direct application of colour through the screen onto the ware.

The term "colour" is used herein to denote a material which can be used to decorate an article. The colour would usually have the consistency of a viscous liquid when applied to an article.

A process which is well established for decorating such tableware is by means of an off-set printing machine comprising a deformable pad, for example of gelatine, in the shape of an inverted dome which transfers colour from an intaglio plate to the ware. The plate may be engraved or etched.

Both the foregoing processes, direct screenprinting and off-set printing from an intaglio plate, offer an advantage over other, traditional, ways of decorating, for example transfer pressing and hand painting, in that, while both processes call for skill in the preparation of the screens or plates, as is also required in making transfers, they do not call for such highly skilled operatives in the pottery where the ware is decorated. The arranging of transfers on the ware, even if a machine is used to press them on rather than rub them in by hand, requires considerable skill and care.

A problem inherent in direct screen-printing on articles of tableware arises from the surface contours which it is customary for such ware to assume. Direct screen-printing onto a truly flat central area of a piece of so-called flatware or onto a cylindrical surface of a piece of holloware, presents no such problem, but most articles of flatware have a contoured radial profile and the walls of cups are more commonly non-uniform in diameter than uniform, and it is difficult to provide for the required deformation of the screen during application of the colour without leaving any such undesired marks as indicate whereabouts on the surface the operation of applying the colour began and finished.

Direct off-set printing from an intaglio plate by means of a deformable pad has the advantage that the decoration is uniform all over the area of the ware engaged by the pad without evident discontinuities, but the preparation of the plates from which the pad takes the colour, and which requires a high quality plating operation to ensure the surfaces can withstand the wear to which they are subjected by the doctor blade, is becoming increasingly expensive compared with modern processes for preparing screens.

It has been proposed in United Kingdom Patent Specification 737 461 to apply colour by screen-printing onto an intermediate flat surface, and then to transfer the colour from such surface directly onto a piece of ware by means of a deformable gelatine off-set printing pad in the shape of an inverted dome, thus to obtain the advantages of screen-printing to obtain the desired design in colour and of the pad to apply the colour to the ware without discontinuity. However, an off-set screen-printing process as described in said specification has not, so far as we are aware, been used industrially, and laboratory trials carried out by the applicant company resulted in unsatisfactory products due to the spreading of colour and the loss of definition of the design as successive prints were obtained.

It is an object of the present invention to provide an improved off-set screen-printing process suitable, for example, for the application of designs to contoured surfaces of articles of ceramic tableware.

It is another object of the present invention to provide an improved off-set screen-printing machine which enables successive designs in colour to be applied uniformly to ceramic ware without significant loss of definition.

The invention provides a repetitive production process for applying a design in colour to the surfaces of a succession of articles wherein in each cycle of operations the design in colour is applied by a screen-printing process to an intermediate surface and is then transferred from said surface to the surface of an article by means of a deformable domeshaped transfer pad, the intermediate surface for each cycle being free or substantially free from residual colour left over from a previous cycle.

The transfer pad may be of any material that is suitable for use with the particular type of colour and the particular type of article to which the colour is applied. In the decoration of ceramic ware it is usual to use transfer pads made of gelatine, though the use of pads made from silicone rubber is increasing.

Both those types of pads can be used in carrying out the present invention.

In one preferred manner of performance of the invention, a sheet material is used to provide the intermediate surface, a fresh area being presented for application of colour in each cycle of operations. The sheet material is preferably one which can be regarded as significantly not non-absorbent, but on the other hand not sufficiently absorbent to result in loss of definition of the design by spontaneous spreading of the colour over the surface.

Paper is the preferred sheet material. For convenience the intermediate surface may be constituted by a roll of sheet material which is advanced step-by-step between successive applications of colour, to present a fresh area for each application. Alternatively the sheet material could be used in the form of separate sheets.

The invention also provides an off-set screen-printing machine suitable for use in decorating articles of ceramic ware, comprising screen-printing means comprising a screen enabling a design in colour to be applied by a screen-printing process to an intermediate surface, an article support for supporting an article to which the design in colour is to be applied, and a deformable dome-shaped transfer pad for transfer of the design in colour from the intermediate surface to the article, the machine being operable cyclically in such a manner that, in each cycle of operation first registration is effected between the screen and the intermediate surface and the design in colour is applied through the screen to the surface, second registration is effected between the transfer pad and the intermediate surface and the design in colour is picked up from the surface by the pad, and third registration is effected between the article support and the pad and the design in colour is transferred from the pad to an article on the article support, the machine comprising means arranged to provide for said first registration in each cycle of operation an intermediate surface that is free or substantially free of residual colour from a previous cycle.

In one preferred form of machine according to the invention said means arranged to provide an intermediate surface comprises means for supporting a roll of sheet material to be used to provide the intermediate surface, and means whereby in each cycle of operation, after the pad has picked up the design in colour from the intermediate surface, the roll of sheet material can be advanced by a long enough step to enable a fresh area of the material to be brought into registration with the screen for the next application of colour through the screen. The means whereby the roll of sheet material can be advanced may be actuated automatically to advance the roll between successive applications of colour thereto.The roll-supporting means may comprise a dispensing roll, arranged to support a roll of sheet material, and a power-driven take-up roll, on which the sheet material is to be wound up, for advancing the sheet material a step at a time after each engagement thereof by the pad and before the application of further colour thereto. A presser roller may engage the upper surface of the sheet material adjacent the take-up roll, the presser roller engaging the material only at intervals spaced apart across its width. The machine may comprise means for varying the length of step of advancement of the sheet material.

The roll-supporting means may comprise a hard flat perforate platform on which the sheet material of the roll is supported when it is engaged from above by the pad, the machine comprising means operative to reduce the air pressure beneath the platform at least for an initial period during ascent of the pad after engaging the intermediate surface, to hold the sheet material by suction on to the platform. Suction may also be applied to the under side of the sheet material when colour is applied through the screen.

The machine may comprise a frame on which the transfer pad, in the shape of an inverted dome, and the screen are mounted for vertical reciprocation in side-by-side relationship, and a horizontally reciprocable table on which the article support and the rollsupporting means are mounted, the machine comprising means operative to move the table to-and-fro when the pad and screen are in raised positions to bring the intermediate surface into register with the screen and the pad alternately.

Whereas a roll of sheet material used to provide the intermediate surface may be advanced step-by-step in a straight path to provide fresh areas for successive applications of colour, it could be advanced in a zig-zag path to allow closer "packing" of the areas contaminated by residual colour, thus to economise in material.

While the use of paper or other disposable sheet material, in roll or other form, is highly effective, there are some disadvantages associated with its use. First the mechanism provided to move and to locate the sheet material may be relatively complex. Second, it is of course necessary to provide replacement supplies of sheet material from time to time.

Third, where the sheet material is paper, as the paper is somewhat absorbent only a proportion of the colour applied to the paper is transferred from the paper to the ware, and the remainder, often amounting to approximately 30% of the colour applied, is thrown away with the paper. To overcome these disadvantages, in another preferred manner of performance of the invention the intermediate surface is scraped free, or substantially free, by blade means of any residual colour remaining from a previous cycle, before the design is applied to it. To this end, in an alternative form of machine according to the invention said means arranged to provide an intermediate surface comprises a transfer plate affording a flat non-absorbent surface constituting the intermediate surface, and blade means arranged to scrape residual colour from the intermediate surface, the blade means operating in each cycle of operation, before the application of colour through the screen, to scrape the intermediate surface free or substantially free of any residual colour remaining from the previous cycle.

The intermediate surface is preferably a highly finished metallic surface which is scraped free of residual colour by means of a blade resembling a doctor blade. The arrangement is such that the blade does not scratch the intermediate surface in use, and to this end the blade is preferably made of a softer material than that providing the surface; for example, the blade may be of a nylon material.

The blade is preferably wiped after each scraping operation to remove colour therefrom. In a preferred arrangement, the relative movement between the blade and the intermediate surface that occurs during the scraping process is continued after the blade and surface are no longer in contact with each other, the continuation of that movement causing the blade to come into contact with a wiper which wipes colour from the blade, the blade and wiper then separating from each other. Preferably any colour wiped from the blade by the wiper passes gravitationally to collecting means located beneath a wiping edge of the wiper, the collecting means being of a capacity great enough to accommodate colour wiped from the blade during a plurality of cycles.

There now follows a detailed description, to be read with reference to the accompanying drawings, of two printing machines, each of which illustrates the invention by way of example.

In the accompanying drawings: Figure 1 is a perspective view from the front of a first machine, with parts broken away.

Figure 2 is a perspective view from the front of the second machine, with parts broken away; and Figure 3 shows a feature of the second machine diagrammatically and to a larger scale.

The first machine comprises a frame 10 arranged to stand on the floor and having a table top 1 2 from which corner pillars 1 4 stand up to support a horizontal upper plate 1 6 of the frame.

A pad support 1 8 and screen support 20 are mounted side-by-side on the plate 1 6 for vertical reciprocation. Thus, the pad 1 8 includes two sleeve portions 22 slidable on vertical posts 24 depending from the plate 1 6. Mounted on top of the plate 1 6 is a hydraulic piston-and-cylinder unit 26 from which a piston rod 28 projects downwardly through the plate 1 6 and is secured to the support 1 8. Mounted on a flat under surface of the support 1 8 is a deformable gelatine pad 30 in the shape of an inverted dome.

The screen support 20 also has two sleeve portions 32, slidable on posts 34 depending from the under side of the plate 1 6. A piston rod 36 of a pneumatic piston-and-cylinder unit 38 secured to the underside of the plate 1 6 is connected to the support 20. The support 20 is in the form of an open Ushaped bracket laid on its side so that one branch of the U provides a lower one of two parallel horizontal arms 40 on which a screen 42, consisting of a design-bearing mesh 44 mounted in a frame 46, is secured in a horizontal position.

Mounted on a horizontal bar 48 constituting part of the frame 10 and disposed behind the support 20 are two forwardly projecting horizontal guide posts 50 on which a slide 52 is carried for to-and-fro reciprocation under the influence of a hydraulic piston-and-cylinder unit 54. A horizontal shaft 56 is rockable about its axis in bearings 58 supported below the slide 52 and adjustable upwards and downwards by screws rotatable by knobs 60.

A rocker arm 62 secured to one end of the shaft 56 beyond its bearing is arranged to be actuated to rock the shaft through a small angle by a double-acting pneumatic pistonand-cylinder unit 64. Mounted in an inclined position on the shaft 56 is a bracket 66 which carries a support 68 for a squeegee 69. The squeegee 69 can thus be raised off and lowered onto the screen 42 by rocking the shaft 56 upon actuation of the unit 64.

A carriage 70 is mounted to slide horizontally from side to side on hexagonal guide bars 72. Such reciprocation is effected by a hydraulic piston-and-cylinder unit 74 disposed in a transverse channel 76 of the table top 12, a piston rod (not shown) of the unit 74 being secured to the carriage 70.

On the carriage 70 is a ware support 80 with centring arms 82 and a vacuum holder 84 for centring and holding a circular piece of flatware in a conventional manner not further described herein. On the carriage 70 is also mounted means 90 for supporting a roll of paper 92. The means 90 comprises a hard flat perforate platform 94 upon which a portion of the paper rests, the roll being initially placed on a dispensing roll (not visible in the drawing) behind the platform and disposed low enough for the paper to be drawn taut over the platform by a take-up roll 96 to which the leading end of the paper is attached.The roll 96 is arranged to be driven step-by-step by an electric motor 98 which can be switched on and off at adjustable step lengths by switching means (not shown) controlled by a rotatable metering device riding on the paper (and thus not influenced by the gradually increasing diameter of the roll as the paper is rolled up). This metering device takes the form of a presser roller 100 which also serves to assist the holding of the paper down onto the platform. (The roller 100 does not have a continuous cylindrical surface over its whole length, but is relieved at intervals at 102 to avoid its picking up, as it will be seen hereinafter would otherwise by likely, an undue amount of excess colour as the paper is wound up). Gearing 97 from the motor 98 to the roll 96 is only partially visible in the drawing, being concealed behind a bracket 104 of the means 90.

Provision (not visible in the drawing) is also made in the roll-supporting means 90 for reducing air pressure under the platform 94 so that the paper laid over it is held down by suction, especially when, as hereinafter described, the pad 30 is raised to pick up colour from the paper.

Electrical control means (not shown) operates pneumatic and hydraulic valves of the machine in suitable sequence so that, in the cycle of operation of the machine from a condition in which the roll-supporting means 90 is in register below the screen support 20 and a piece of ware ready to be decorated is on the support 80 in register below the pad 30 (which has colour on it which it has just picked up from the paper), the piston-andcylinder units 26 and 38 are actuated to bring the pad 30 down in an operating stroke to impress the design in colour onto the ware and to lower the support 20 so that an under side of the screen frame 46 bears on the paper, which is preferably also subject at this time to suction to hold it steady on the platform 94.While the pad is executing its operating stroke, the short descent of the support 20 taking negligible time compared with the stroke of the pad support, the squeegee 69 is rocked down onto the screen 42 and executes an operative stroke (under the influence of the unit 54) across the screen (from front to rear of the machine). The squeegee is raised and brought forward again and the support 26 is raised to lift it clear of the deposited colour. (A reservoir of colour is maintained on the screen by hand, or by automatic feed, if preferred).

The pad 30 is also raised after impressing the design on the ware, and when both screen support 20 and pad 30 are clear, the carriage 70 moves to the right hand end of its stroke to its position shown in the drawing under the influence of the piston-and-cylinder unit 74. The ware support 80 is now in a loading and unloading position where the piece of ware bearing the design is replaced by a fresh piece, either by hand or automatically. At this stage, the portion of paper to which the design (indicated as 110 in the drawing) has been applied is in register and below the pad 30. The pad 30 is now brought down again (while the screen support 20 remains up) into pressing engagement with the paper, thus, on its ascent to pick up the design from the paper.When it is clear of the paper, the carriage returns to the left (viewing the drawing) and during this movement, the take-up roll 96 is actuated by the motor 98 to advance the paper a measured step as determined by the roller 100 so that residual colour left on the paper is moved away from the area coverea by the design on the screen 42, a fresh portion of paper thus being placed in register with the screen ready for application of the next design.

The roll of paper is wound up on the roll 96 and, when it is finished, is replaced by a fresh one on the dispensing roll. The old roll is then thrown away. The relieving of the roller 100 at 102 militates against the build up of an undue amount of residual colour on the roller.

The paper of the roll 92 may be a suitable "half-sized" paper (i.e. a paper which is not completely sized to seal it, but is not as porous as blotting paper) which is cheap enough to allow it to be thrown away after being used once. The paper should not have been sealed to render it non-absorbent, at least not on the side that is going to receive the colour, but must be strong enough not to tear under the conditions of use. Papers used in photographic reproduction machines and sold under the brand names "RONEO" and "XEROX" may be technically very suitable, but less expensive papers of similar strength and absorbency may be available.

The second machine (Figs. 2 and 3) is in many respects of very similar construction to the first machine, and the same reference numerals are used in Fig. 2 as in Fig. 1 to indicate corresponding components of the machine. The construction of the second machine will only be described hereinafter insofar as it differs from the first machine.

In the second machine, the carriage 70 does not carry means for supporting a roll of paper, nor does it carry a perforate platform.

Mechanism for metering paper and for holding the paper on to the platform is also not present. Instead of these parts the carriage 70 carries a backing plate 120, attached to its upper surface. The backing plate is of a material sold under the Registered Trade Mark "TUFNOL". Secured on top of the backing plate 120 is a transfer plate 121 of chromium-plated steel, an upper surface 1 22 of the plate being flat, horizontal and highly finished to a mirror-finish. The size and disposition of the transfer plate is substantially the same as for the perforate platform 94 of the first machine.At that end of the transfer plate nearer the ware support 80 a marginal part 1 23 of the transfer plate projects beyond the backing plate 1 20 so as to leave a space between the marginal part 1 23 and the adjacent part of the carriage 70 (see Fig. 3).

Beyond the marginal part 1 23 of the transfer plate there is a wiping strip 1 24 secured to the carriage 70. The wiping strip extends across the carriage at right angles to the direction of travel of the carriage, and its length is at least as great as the length of the adjacent marginal part 1 23 of the transfer plate. The height of the wiping strip is such that its upper surface 1 25 is slightly above the upper surface 1 22 of the transfer plate, and the wiping strip is so disposed that there is a narrow gap 1 26 between the wiping strip and the transfer plate. That edge 1 27 of the upper surface 1 25 adjacent to the gap 1 26 constitutes a wiping edge.Part of the wiping strip is cut away, as shown, to afford a continuation of the space beneath the marginal part 1 23 of the transfer plate. An open-topped tray 1 28 occupies that space, a central part of the tray being disposed beneath the gap 126. The tray is at least as long as the wiping strip 1 24 and is so mounted that it can be slid lengthwise into the space and from the space at will. A catch may be provided to secure it releasably in position.

A wiper blade 1 29 is provided above the transfer plate 1 21 to co-operate with the plate as described below. The blade is of a nylon material which is softer than the materials of which the transfer plate 121 and the wiping strip 1 24 are made. The blade 1 29 is mounted on a holder 1 30 for pivotal movement about a horizontal axis at right angles to the direction of travel of the carriage 70. The blade can be pivoted between an operative position, as shown in the drawings, and an inoperative position in which it is raised above the levels of the upper surface 1 22 of the transfer plate and the upper surface 1 25 of the wiping strip.One end of an arm 131 connected to the blade holder 1 30 is pivotally connected to the end of the piston rod of a pneumatic piston-and-cylinder unit 132, so that operation of the piston-and-cylinder unit rocks the arm and moves the blade between its operative position and its inoperative position. In its operative position the blade may conveniently be inclined at about 60 to the horizontal; it is unlikely that the blade could operate satisfactorily if in its operative position it were inclined at less than 45 to the horizontal.

It will be appreciated from the foregoing description that the blade with its associated mounting, etc. closely resembles a doctor blade of the kind used in removing colour from the top surface of an intaglio plate.

The second machine operates in the following manner. The carriage 70 is moved to a first end position in which the transfer plate 1 21 is in register with the screen-printing means and a design in colour is screen-printed onto the upper surface 1 22 of the transfer plate. The carriage is then moved to a second end position in which the transfer plate is in register with the transfer pad 30. During that movement of the carriage, the wiper blade is in its inoperative position. When the carriage has reached its second end position the pad is lowered and raised again to pick up colour from the transfer plate. The carriage is next returned to its first end position. Throughout that return movement the blade 1 29 is maintained in its operative position.The blade acts to scrape any remaining colour from the upper surface 1 21 of the transfer plate. Although a trace of colour may remain on that surface, the amount remaining is too small to affect adversely the next cycle of operation. As the blade scrapes the surface, the colour from the surface builds up to form a ribbon of colour on the blade adjacent to the lower edge of the blade. During the final stages of return movement of the carriage the transfer plate 1 21 passes beyond the blade, and the blade is immediately engaged by the wiping edge 1 27 of the wiping strip 1 24. That edge 1 27 engages the blade sufficiently far above the lower edge of the blade to ensure that the ribbon of colour on the blade lies wholly below the wiping edge.Continued movement of the carriage causes the ribbon of colour to be wiped from the blade onto the end face of the wiping strip below the wiping edge 1 27 and bordering the gap 1 26. When the carriage reaches its first end position the blade is raised from the upper surface 1 25 of the wiping strip to its inoperative position.

The transfer pad 30 is lowered and raised again to transfer the design to an article of ware on the ware support 80, while the screen-printing means operates again to apply the design in colour to the transfer plate 121.

The carriage again moves to its second end position and the cycle continues as described above.

The colour is in the form of a viscous liquid, so that when the ribbon of colour is wiped from the blade it flows downwards through the gap 126 and drops into the tray 128. The rate of flow is such that there is no build up of colour immediately beneath the wiping edge 1 27. Before the tray becomes full it can be removed and emptied, the colour thus recovered being used again in the process.

Claims (26)

1. A repetitive production process for applying a design in colour to the surfaces of a succession of articles wherein in each cycle of operations the design in colour is applied by a screen-printing process to an intermediate surface and is then transferred from said surface to the surface of an article by means of a deformable dome-shaped transfer pad, the intermediate surface for each cycle being free or substantially free from residual colour left over from a previous cycle.

2. A process according to claim 1 in which said intermediate surface is constituted by a sheet material which, while not sufficiently absorbent to result in loss of definition of the design by spontaneous spreading of the colour over the surface, is significantly not non-absorbent, a fresh area of material being presented for application of colour in each cycle.

3. A process according to claim 2 in which said sheet material is paper.

4. A process according to any one of claims 1, 2 and 3 in which said intermediate surface is constituted by a roll of sheet material which is advanced step-by-step between successive applications of colour to present a fresh area for each application.

5. A process according to claim 1 in which before the design is applied to it, in each cycle of operations, the intermediate surface is scraped free or substantially free by blade means of any residual colour from a previous cycle.

6. A process according to claim 5 in which after scraping the intermediate surface the blade means is wiped to remove colour therefrom.

7. A process according to any one of claims 1, 5 and 6 in which the intermediate surface is a highly finished metallic surface.

8. An off-set screen-printing machine suitable for use in decorating articles of ceramic ware, comprising screen-printing means comprising a screen enabling a design in colour to be applied by a screen-printing process to an intermediate surface, an article support for supporting an article to which the design in colour is to be applied, and a deformable dome-shaped transfer pad for transfer of the design in colour from the intermediate surface to the article, the machine being operable cyclically in such a manner that, in each cycle of operation first registration is effected between the screen and the intermediate surface and the design in colour is applied through the screen to the surface, second registration is effected between the transfer pad and the intermediate surface and the design in colour is picked up from the surface by the pad, and third registration is effected between the article support and the pad and the design in colour is transferred from the pad to an article on the article support, the machine comprising means arranged to provide for said first registration in each cycle of operation an intermediate surface that is free or substantially free of residual colour from a previous cycle.

9. A machine according to claim 8 in which said means arranged to provide an intermediate surface comprises means for supporting a roll of sheet material to be used to provide the intermediate surface, and means whereby in each cycle of operation, after the pad has picked up the design in colour from the intermediate surface, the roll of sheet material can be advanced by a long enough step to enable a fresh area of the material to be brought into registration with the screen for the next application of colour through the screen.

10. A machine according to claim 9 in which the means whereby the roll of sheet material can be advanced is actuated automatically to advance the roll between successive applications of colour thereto.

11. A machine according to claim 10 comprising a dispensing roll arranged to support a roll of sheet material to be used as the intermediate surface and a power-driven takeup roll on which the sheet material is to be wound up, for advancing the sheet material a step at a time after each engagement thereof by the pad and before the application of further colour thereto.

1 2. A machine according to claim 11 comprising a presser roller which engages the upper surface of the sheet material adjacent the take-up roll, the presser roller engaging the material only at intervals spaced apart across its width.

1 3. A machine according to any one of claims 9 to 12 comprising means for varying the length of step of advancement of the sheet material.

14. A machine according to any one of claims 9 to 1 3 in which the roll-supporting means comprises a hard flat perforate platform on which the sheet material of the roll is supported when it is engaged from above by the pad, the machine comprising means operative to reduce the air pressure beneath the platform at least for an initial period during ascent of the pad after engaging the intermediate surface, to hold the sheet material by suction on to the platform.

1 5. A machine according to claim 14 comprising means whereby suction is applied to the under side of said sheet of material, in the operation of the machine, also when the colour is applied through the screen.

1 6. A machine according to any one of claims 9 to 1 5 comprising a frame on which the transfer pad and the screen are mounted for vertical reciprocation in side-by-side relationship, and a horizontally reciprocable table on which the article support and the rollsupporting means are mounted, the machine comprising means operative to move the table to-and-fro when the pad and screen are in raised positions to bring the intermediate surface into register with the screen and the pad alternately.

1 7. A machine according to claim 8 in which said means arranged to provide an intermediate surface comprises a transfer plate affording a flat non-absorbent surface constituting the intermediate surface, and blade means arranged to scrape residual colour from the intermediate surface, the blade means operating, in each cycle of operation, before the application of colour through the screen, to scrape the intermediate surface free or substantially free of any residual colour remaining from the previous cycle.

1 8. A machine according to claim 1 7 in which the intermediate surface is a highly finished metallic surface.

1 9. A machine according to claim 1 7 in which the blade means comprises a blade of a softer material than that providing the intermediate surface.

20. A machine according to claim 1 9 in which the intermediate surface is a highly finished metallic surface and the blade is of a nylon material.

21. A machine according to claim 17 in which a blade of the blade means, after scraping the intermediate surface contacts a wiper which wipes colour from the blade.

22. A machine according to Claim 21 in which colour collecting means is located beneath a wiping edge of the wiper to collect colour wiped from the blade.

23. A repetitive production process for applying a design in colour to the surfaces of a succession of articles by off-set screen-printing, carried out substantially as hereinbefore described with reference to Fig. 1 of the accompanying drawings.

24. An off-set screen-printing machine, suitable for use in decorating articles of ceramic ware, substantially as hereinbefore described with reference to Fig. 1 of the accompanying drawings.

25. A repetitive production process for applying a design in colour to the surfaces of a succession of articles by off-set screen-printing, carried out substantially as hereinbefore described with reference to Figs. 2 and 3 of the accompanying drawings.

26. An off-set screen-printing machine, suitable for use in decorating articles of ceramic ware, substantially as herinbefore described with reference to Figs. 2 and 3 of the accompanying drawings.