Paul Scott Ceramics and Print 1994 – History, Lithography, Intaglio, Silk Screen, Photography, Decals

Ceramics and print and industry have a long history – below I have condensed Paul Scott’s book Ceramics and Print but have expanded the areas of lithography, intaglio printing, silk screening, photography, and decals as relevant to my research. All text is word for work from the book.

The first use of ‘print’ in the context of transferring a ceramic color from one body to another (other than painting) appears to be the use of natural sponges  to decorate Minoan and Mycenaean Pottery. Referred to as ‘splatterware’ by some archaeologists. Its use was said to be to imitate the decoration on ostrich eggs. Whatever the reason, the sponges were used in a relatively random way to produce a mottled effect in contrasting slip on a clay body.

For Centuries the only other printing on clay appears to have been the use of wooden, clay or other stamps, natural or hand made, to decorate by impressing into the clay surface. Stamps facilitated the simple repitition of shapes creating patterns and designs.

By the beginning of the 17th century engraving and etching was a finely developed art. Although individual printmakers did explore the possibilities of the media (Durer and Rembrandt are well-known for having used etching as a creative media), printing was, before the advent of photography, the main method of illustration and reproduction of images.

Potters at the same time were discovering metal oxides which would give increased ranges of ceramic colors and these were painted onto tiles, plates and tableware, cobalt blue first seen on Chinese ware became popular during the 17th century, on Dutch and English ‘delftware’, and colors of purple , yellow, green and orange were developed.

The exact date of the discovery or invention of ceramic transfers is open to debate. Until recently, the most quoted is a John Sadler of Liverpool, who in 1749 is said to have observed children sticking bits of paper to broken pottery; six years later he swore an affidavit which claimed that he and a colleague had perfected a printing system. Robert Copeland in his book, Spodes Willow Pattern, cites evidence that transfers were used in the Doccia Factory as early as 1737, but whatever the ins and outs, by the end of the 18th century printing from copper plates was common in the pottery industry.

At first it was by a system of ‘bat printing’. Copper plates were engraved by skilled craftsmen using a range of specialist tools. Images were built up using cut lines and punched dots. Then the plate was ‘inked up’ using a soft rag or cloth soaked in oil and the surface wiped clean with ‘with the hand as in common copper plate printing’. The image on the plate in oil was transferred to the fired ceramic surface with the aid of a glue ‘bat’ approximately one quarter inch thick. This bat was pressed onto the copper plate, thus picking up the oil impression of the plate. Upon separation from the plate the bat was placed face up on a ‘boss’ ( a soft leather bag filled with bran or wool) before being pressed onto the fired ceramic surface. The oil transferred from the bat to the pottery surface which was then dusted with ceramic color. The ceramic pigment stuck to the oiled area and so the image from the copper plate appeared. This method of transferring images was probably the first used, but because the amount of ceramic color held by the oil after dusting was limited it was only suitable for on-glaze, or enamel colors. Underglaze demanded a heavier deposition of ceramic pigment.

Around this time, paper-making machinery was invented that made possible the production of large quantities of smooth, shiny paper. This and the development of printing presses that were operated by power not hand had dramatic effects on the spread of information. They also made possible development of a suitable tissue paper, which replaced the glue or gelatine bat as the main transfer medium for pottery printing.

The use of paper transfers and the developments of ceramic inks meant that underglaze colors could be used, and the process was adapted so that is was practical to use on biscuit ware.  So the famous ‘Staffordshire blue’ pottery evolved. Cobalt was the prime ceramic oxide used, and a wide range of blues were developed. Thousands and thousands of engraved designs grace the surface of Blue and White pottery during the 19th century.

Lithography: Munich playwright/composer Senfielder discovered the process of lithography in 1797. Lithography (from the Greek ‘lithos’ – ‘stone’, and ‘graphio’ – ‘draw’) relies on the natural repulsion between grease and water. Paper applied to the inked up slab picks up the image from the drawn area. By repeating the process, numerous identical images can be printed. At first lithography was exploited by the paper printer, and it was in continental Europe that it was first adapted for use on pottery. It was some time before the British pottery industry took it up with any enthusiasm.

Specialist adaptions of tissue paper were produced to make the process workable. Duplex paper (used until relatively recently) consisted of a thin sheet of tissue with a much thicker paper backing. The thick paper backing allowed for stability in printing colors in register, and this was removed before the image was transferred to the ware. The tissue possessed the flexibility for transfer to curved ceramic shaped. Ceramic surfaces were painted with a weak varnish, which when tacky held the lithographically produced print.

Zinc plates have since replaced stone. The lithographic process was, and is still used, primarily for on-glaze or enamel colors. The general consensus has been that as with bat printing process, ink thickness is fine and unsuited for underglaze decoration. Still after the introduction of photographic lithographs, it was possible to photographically transfer images from engravings and wood blocks onto lithographic plates, and it has been suggested that a number of printed tiles and underglaze decoration on pottery toward the end of the 19th century were lithographically produced.

Screen printing: Screen printing, a development from stenciling, first appeared in Japan and its invention is attributed to Yutensai Miyassak in early 18th century. It wasn’t until the early 1900’s that screen printing, as we recognise it today, was in use. Its first industrial application was onto fabrics, and by using a cut stencil process. In 1939 in New York Anthony Velouis developed a process which dispensed with the cut stencil. The blank screen was drawn onto with a waxy of lithographic crayon, the washed with a glue solution. When the glue set a solvent was poured overt he front and back, dissolving he was; creating open areas of the screen there the image was originally drawn. Subsequently, photographically sensitive emulsion made screen printing a even more versatile medium.

In ceramics, the pottery industry first used screen printing for tile decoration but not until the 1950’s in the UK. The first silk screen printed tiles in England were attributed to Carter of Poole. Now it is the prime process for ceramic decoration in industry, either in the printing of decals or direct printing. The process is so versatile that not only does it allow printing on the flat, but is possible to print directly onto the cylyndrical shapes (mugs etc), to print with wax resist, onglaze, underglaze, heated thermoplastic colors (so that a decorated piece does not need another firing).

Its combination with photographic processes was the key which unlocked the door to its mass use in industry. The other key was the development of ‘decals’: Ceramic color is printed onto a special gummed paper, over which a thermoplastic layer is printed in liquid form. The ‘cover-coat’ as it is called, sets on drying, including the ceramic image in its body. When placed in warm water it is possible to slide off the cover-coat sheet with the ceramic image in place. The residues of the gum allow it to stick onto a ceramic surface. On firing the plastic burns out leaving the printed image in or on the ceramic surface.

– making decals: Usually decals are made by printing an image or design in oil-based ceramic inks onto a specially gummed paper. The paper is called ‘Decal’ paper (it was known for many years as ‘thermoflat’ paper) When dry, the paper with its printed image is coated with a liquid lacquer or varnish called ‘covercoat’, which on drying becomes a thin plastic sheet including the printed image.Covercoat can be applied by painting, but is normally applied by squeegeeing through a blank silk screen. The lacquer should only be used in well-ventilated areas, and this includes drying covercoated sheets of prints. Once dry, if placed in warm water, the plastic sheet including the print, will slide off the gummed paper. This can then be placed onto the ceramic surface, usually glazed or polished, where it can be slid around until correctly positioned. It is then firmed into place with a rubber kidney.

Deciding on a mesh depends on the level of sophistication of the designs and printed quality required. Bold, large shapes with little detail will probabley be best produced on a coarser screen of 100 threads (43 threads per cm), whereas for photostencils using half tones a finer screen of 230 threads per inch (90 per cm) would be more suitable. Ceramic pigments are generally coarser than ordinary inks. Underglaze colors for example are routinely passed through an 80s mesh (80 threads per inch) before sale, although on-glaze colors are ground finer to at least 200s mesh. So, using underglazes through a 230s mesh might be problematic, especially when in speicalist books the advice is that mesh size should be at least 2.5 to 3 times the size of the pigment particles.

Ceramic inks can be purchased from commercial suppliers. They are usually on available in large quantities and as on-glaze inks (onglaze colors are most commonly used as inks in decals, because prints are normally applied on top of a fired glazed surface. After application of the decal, the piece is then only requires a low temperature firing to mature the onglaze colors). It is possible to mix up inks and a number of water-based and oil-based  media are now readily available from ceramic suppliers. Color should be mixed with a palette knife or glass muller, in the ratios of 1 part medium to 2 parts ceramic pigment

Photography: The first printing of a photographic image on a ceramic surface was undertaken by Lafon de Camarsac in France in 1854, using a gum bichromate system. This relied on the light sensitive chemical potassium bichromate. Mixed with gum arabic, and a sticky substance like honey, it was coated onto a ceramic surface and exposed to light through a positive transparency. Where light hit the surface of the tile, it fixed the gum; where is was darker the substance remained proportionately sticky to the amount of light fallling onto its surface. The result was a latent photograph, revealed when ceramic pigment was dusted onto its surface. Where the gum hardened no pigment adhered, but pigment did adhere to those area un – or under-exposed. It appears that he also used a system where ceramic pigment was mixed into the light sensitive emulsion. In 1868 Lafon de Camarsac was marketing a system of producing portraits on porcelain. The most interesting use of the technology was in the production of ceramic photographs for gravestones. In areas of France, Italy and Switzerland the practice is still followed, ceramic photographs are common sights in graveyards.

However, photography’s greatest impact in printing and ceramics lies not in direct photographic emulsions but in the use of photosensitive emulsions used in intaglio, lithography and screen printing.

Current industrial uses and developments: New colored inks make any color that is printable on paper, printable on ceramic. In response to the health and safety and environmental problems of solvent-based products, new ultraviolet (UV) curing media are being researched. The old glue bat process of transferring color and designs to was has been resurrected and refined. In pad printing, a process that involves spcreen printing, and offsetting, gelatine or silicone pads now transfer images that have been screen printed onto a flat plastic or glass surface, onto a curved ceramic one.

The advent of microprocessors and the dawning of the computer age has resulted in new developments industrially, many to do with mechanisation, but also to do with image production.

Intaglio Printing: As with dry point and engraving prints are made by inking the plate, removing the excess, and printing in an etching press with damp paper. For ceramic prints, pottery tissue is used as the paper; oxides or underglaze colors thoroughly mixed with copperplate oil using a palette knife or glass muller, as the inks. Pottery tissue is applied to the ceramic surface after printing, and rubbed down, transferring the image. Althought dry pint and etched plates have been seldom used in the pottery industry, it is possible to obtain fire-able prints from both.

The dusting on process, where printing takes place using oil instead of ink, and where the carrier is gelatine instead of tissue, is relatively simple from etched, engraved or dry point plates. Gelatine pads can be make from gelatine purchased from the supermarket or chemist. Using a stronger mix than normally recommended for food purposes, pour a gelatine miz onto a tile or glass plate enclose by four walls stuck to the surface using masking tape. When cool, the gealtine forms a pad which is removable with care. The pad may be susceptible to easy breakage at first, so some time should elapse before attempting to free the gelatine.

The pad will remain usable for some time, but eventually it will become brittly and hard. When working with an etched, engraved or dry point plate, copperplate oil is used as the ‘ink’. The gelatine pad is placed onto the plate, and pressed firmly into place. On lifting the pad from plate, it is placed face down onto the glazed ceramic surface with slight pressure. The gelatine pad is then removed. A latent image now exists on the glazed surface which may be revealed by dusting on a ceramic color.

These methods, although tried and tested in the pottery industry do have limitations; The amount of color needed for a print to work on a ceramic surface is greater than a paper one, and imperfect working procedures can make it a hit and miss affair for the individual maker, but they do work.

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