(This isn't a full student paper but rather excerpts from my Master's thesis)
Chapter 1: An introduction of printmaking inks
1.1: Introduction
Because this paper focuses on lithographic inks, there also needs to be an understanding of how they differ and relate to other printing inks. The following chapter outlines this information, though is not a comprehensive review. While researching this topic, it became apparent that there are issues concerning terminology in the literature on printing inks and on lithographic inks specifically. To avoid confusion, especially if additional information is sought from the bibliographic literature, this chapter will also address some of the issues in terminology which were found while researching the subject.
1.2: A technical breakdown of printing inks
Printing inks can be broken up into several components. The labeling of these components differs depending on the source. Helmut Kipphan, author of the Handbook of Print Media Technologies and Production Methods[1], divides the components of printing inks into four categories: Colorants, Vehicles, Additives, and Carrier Substances. The table Kipphan uses in his work (Fig.1) shows his division of ink components as he defines them. Finley’s Printing Paper and Ink divides printing inks into two components: Colorant and Vehicle[2]. The colorants create the desired color of the ink and the term vehicle is used to refer to the liquid portion of the ink which carries them.[3] This ‘vehicle’ contains all the components with exception of the colorants. Both examples are given as ways to understand printing inks, but Finley’s model will be the one deferred to within this thesis as it is a simple way to explain and introduce the subject.
The literature referred to here, along with the Leach’s The Printing Ink Manual,[4] are all modern publications on the current ink manufacturing industry. They concern themselves with the current printing inks which are industrially manufactured and include: offset lithography, gravure, flexographic, typographic, and ink jet inks. For this reason, the breakdown of ink components seen in these writings and reflected here can seem complicated due to the many possible ingredients that need to be accounted for within the variety of inks they address. The printing inks of today have many more ingredients and means of productions than the historical ink recipes seen in the 18th and 19th centuries which will be addressed in the historical review of lithographic inks. The reason for addressing this issue is that Finley's division when explaining the potential components in printing inks makes a distinction between solvent and oil. Finely described solvents as the ‘liquid part’ of the ink, however, it is often the processed oil which fills this role in early lithographic inks, as will be seen in Chapter 2.
The vehicle of the ink is composed of the other ink ingredients and determines all of the ink’s properties outside of its color. An ink’s vehicle can contain binding resins, solvents, oils, and additives.
Binding Resins act to bind the pigment particles to the substrate as well as to one another. Binders are resins which are solid compounds which must be dissolved into the ink.[9] Rosin based binders are the most common, but other resins include cellulosics, or cellulose-based resins, and cyclized rubber.[10] Synthetic resins are also used and include acrylic resins, vinyls, maleic resins, polyamides, and epoxies. Resins not only act as binders but can also affect an ink’s drying rate, rub resistance, gloss, and flexibility.[11]
Solvents are defined by Finely as the liquid portion of the printing ink formula, which must perform several functions for the ink to be successful. The solvent acts to dissolve the resin but cannot cause the pigment to bleed. Solvents need to evaporate at a suitable rate but can also affect the flow and adhesion of the resulting inks. Solvents can be alcohols, oils, oil derivatives, or even water. Water-based inks, while historically being some of the first printing inks, have had a resurgence in modern industrial ink making in recent decades due to environmental concerns.[12] As noted earlier, oils are traditionally used as the ‘liquid portion’ in early printing inks, including lithographic inks.
Oils used in printing inks can typically be divided based on their drying mechanism between non-drying oils, like mineral oils, and drying oils, which are vegetable oils like linseed oils and tung oil.[13] The modern ink manufacturing industry makes a further distinction between the oils and typically divides them between non-drying oils, drying oils, semi-drying oils, and quick-set inks. Inks that use non-drying oils depend on the absorbency of the paper to dry. These non-drying oils are often low in cost and chosen for large print runs. Drying oils, instead, oxidize and begin to polymerize when they dry. As the oils dry, they become rigid, which can prevent ink smearing.[14]
The two other oils used in printing inks, semi-dry oils and quick-set inks, act similarly to drying oils. Although given their distinction, the mechanism they use to dry is the same as drying oils, but at different rates. Semi-dry oils oxidize as they dry but at a much slower pace than the oils categorized as typical drying oils. The most commonly used semi-drying oil used in inks today is soya oil, created from soy.[15] It should be noted that setting and drying when referring to inks are two different concepts. Quick-set inks are used in offset lithographic and typographic printing as an ink which will set quickly to allow quick printing but will still need time to oxidize before being completely dry. These inks enable the prints to be created and stacked quickly without smearing but would still smear if abraded before the oil can fully oxidize.[16]
Additives are added to inks to adjust the ink further as needed. Additives include driers, waxes, anti-skimming agents, wetting agents, and stiffening agents. Driers act as their name implies. They are used in combination with drying oils and act as a catalyst to speed up the drying process. The most common driers are cobalt and manganese. Waxes are added to ink as additional rub resistance. Anti-skimming agents are sometimes added to inks with drying oils, as uneven oxidation of the ink can create a skin on the top. The addition of anti-skimming agents is added to prevent this skimming. Wetting agents are added to reduce a vehicle’s surface tension for it to access the pigments more efficiently, which can also affect the flow of the ink, lowering the ink’s viscosity. Stiffening agents achieve the opposite, increasing the ink’s viscosity.[17]
1.3: The lithographic printing process
The differences in printing inks and printing ink ingredients spawn from the different needs of each printmaking process. Because the printing processes themselves differ in their mechanics, the printing inks used must also be designed accordingly. In early printing inks, these differences may not be as noticeable, but as the field of ink manufacturing developed, so too did the distinctions between printing inks as well as the possible ingredients used. As ink manufacturing increased and industrialized, the specificity and accuracy used to create a printing ink have increased.
To understand lithographic ink, attention should be given in how the lithographic process differs from other printmaking methods. Finley’s Printing Paper and Ink describes lithography as a chemical printing process as opposed to relief, intaglio, and screen printing, which are physical printing processes.[18] This difference in terminology is there to point out that processes like that of relief, intaglio, and serigraphy, print by relying on a physical difference in the printed and non-printed areas of a matrix. Meanwhile, the differences between inked and uninked areas of a lithographic plate are flat, thus planographic, and the contrast of these areas in lithography is caused by chemical differences on the matrix’s surface.
Lithography works by utilizing the principle that oil and water will not stick to one another. To make this work, the printing matrix, traditionally a lithographic stone, must be processed and treated to be successfully printed. To begin this process, the image has to be drawn onto the stone either directly or transferred on. A greasy material, usually a lithographic tusche or lithographic crayon, is used to create the image. This drawing then needs to be processed. This step is also called ‘etching’ the stone, although this term is not entirely accurate as no real etching occurs compared to intaglio plate etching. The stone, with its drawing, is covered with several passes of nitric acid and gum arabic.[19] This procedure creates a film on the stone which rejects any new greasy materials. The drawing on the stone is also affected by this treatment but in another way. While the original drawing is still soluble in water, the gum and acid application reacts with the soap in the drawing materials, hardening the drawing and making it insoluble in water.[20] This process creates two chemically different areas of the stone and will subsequently create a printable image.
During the printing process, the lithographic stone or plate is first given a pass of a sponge full of water before the ink roller can roll onto the matrix and deposit ink onto the image areas. The paper is placed over the inked image and, when using a scraper press, is printed by the pressure of the press’ scraper bar, forcing the ink onto the paper (See Fig. 2 & 3 for the process and scraper bar method). Due to this printing mechanism, the amount of ink needed to sit in the processed areas to create a clean image is much less than the amount of ink required for a relief or intaglio print.
Due to the inks’ history and development, relief, intaglio, and lithographic inks often have many similarities. The three types of inks are all paste inks, meaning that they have a high viscosity. Alternatively, flexographic and gravure inks are both processes requiring a quick printing pace and fast application to the matrix, so these inks are considered liquid inks and are very fluid.[21] These relief, intaglio, and lithographic inks are also all inks which use vegetable oils, which are drying oils, that depend on oxidation for their drying method. Traditionally, the primary oil used in creating these inks was linseed oil, with nut oil occasionally seen in early recipes for relief and intaglio inks.[22] Recipes throughout the nineteenth century of intaglio, relief, and lithographic inks all use similar ingredients.Lampblack was traditionally the pigment used in these paste inks, excluding intaglio inks, which had many early recipes calling for Frankfort black, a pigment created from burning vines.[23] Between relief, intaglio, and lithographic inks, the lithographic process requires the least amount of ink to transfer onto the substrate.[24]
In addition to the complexities of manufactured lithographic inks, artists and master printers who use manufactured lithographic inks will modify the ink with other colors or lithographic varnishes to create a better consistency or address problems in the printing process. Colored lithographic inks may be added to black ink to give the black a different desired tone. Lithographic varnishes can be added to the ink to create a softer ink, which may roll up faster and allow for more ink to deposit onto the image area. To make a stiffer ink, printmakers may add magnesium carbonate or talc to the ink.[25] This is not an exclusive occurrence in modern direct lithographic printing but also noted in historical sources as printers often have to edit their inks to best suit the desired printed work.
It should be noted that the proofing process is often the time where the inks are tested and edited to address printing issues. For this reason, the properties of the ink on an early proof print may differ from the properties of an editioned print, as the printer may have added materials to the ink during the proofing process.
Inks can also be edited in the course of printing an edition. It is possible for the water used in the process to affect the ink and cause it to emulsify, creating a short and rubber-like ink that does not distribute well.[26] Additional editing can be made to the ink in reaction to ‘scumming’. Scumming can occur during the printing process, a phenomenon where the roller's ink will begin to build up on non-image areas of the matrix. This issue can be caused due to a variety of reasons but can be addressed by the printer mid-print production. This can be addressed by either treating the printing matrix or editing the ink by adding magnesium carbonate or additional varnish.[27]
1.4: Difficulties in terminology of lithographic inks
It should be noted that lithographic inks used for direct lithography differ from lithographic inks used for offset lithography. This can be confusing when looking into modern ink manufacturing literature as the term ‘lithographic ink’ might be used to mean offset lithographic ink. Offset lithographic printing operates differently from traditional stone or plate lithography, which uses a scraper-bar based press or a direct rotary press. In the offset printing process, the lithographic plate never actually touches the paper; instead, a rotary press is used. The ink offsets onto a rubber roller before the ink transfers to the paper (Fig. 4). Offset inks very often have a high pigment content, between 10% to 30%. The binding agents are usually a combination of hard resin, alkyd resin, vegetable oil, mineral oil, and drying agents. Offset inks need a high viscosity to be successful.[28] Offset inks often have chemical driers added to them, causing them to dry far too quickly to use in hand lithography. Additionally, the amount of ink needed for a hand lithographic print requires a thicker deposit of ink than that of offset, though compared to other printing methods, both lithographic inks layers are very thin.[29]
Additional confusion is possible when the term ‘lithographic ink’ is used to refer to the tusche or ink, which the artist uses to draw onto a lithographic stone to get an ink wash appearance in the lithographic image. This ink is not used for printing but rather to create the image on the stone. These drawing inks and drawing crayons used in image creation are made using wax, soap, tallow, and shellac. Traditionally, these materials would be created by the artist themselves, but today lithographic drawing materials can be bought by manufacturers. There are various recipes for these drawing crayons and litho drawing inks that artists have used, but it goes beyond this research’s scope.[30] The term ‘varnish’ can assist in identifying a lithographic printing ink from a drawing ink. When Senefelder used the term, he referred to prepared linseed oil that has been burned down to the desired viscosity but has not yet had other ingredients added.[31] Later sources maintain that a lithographic varnish is a boil linseed oil that comes in various thicknesses and that some lesser quality varnishes use resin to produce the desired consistency and substitute boiling time.[32] If a lithographic ink recipe includes varnish, it is likely a printing ink.[33]
Roll-up ink is similar to touche in that it is used to prepare the litho stone but not for the printing. Applied after the image has been drawn and the stone has been processed, roll-up ink is used to secure the stone’s imagery. Technically it is an ink used in lithography, but it is typically not used on the prints.[34] Roll-up inks are noted to be softer than the lithographic ink one would use for creating a print. These inks are high in grease content, containing additional wax, tallow, or oleic acids to make them ideal in building up the image for the printing ink.[35]
1.5: Conclusion
As seen, printing inks contain multiple ingredients and all with their uses. The needs of the printing process dictate the specific ingredients used. While relief, intaglio, and lithographic inks are similar due to their history and status as paste inks, their printing processes mean that they vary. This is especially important to note when looking at a print created by direct lithography vs offset lithography. It is important to note that though these are both planographic processes, they are not made with the same aim in mind. Once there is a basic understanding of the factors involved in creating printing inks, it becomes easier to understand the prints they are used to create. The next step to applying this knowledge to an object is to learn about the historical context of these various ingredients. The literature reviewed here is modern and therefore refers to many components that have only been used in inks within the last century. To know what sort of ingredients are used in a print, we need to address these inks’ history.
Chapter 2: History of Lithography and Lithographic Inks
2.1: Introduction
The ink used to create a lithographic print differs depending on the period in which the image was made. If a print date is known, historical knowledge of lithographic ink can provide more insight into the media and what potential issues may be faced while treating the print. For this reason, a historical overview, both of lithography in general and of lithographic ink expressly, is provided here. A timeline is also given as a faster method of accessing these dates. The history of lithography allows us to understand why certain advances in the ink industry happened, the trends, and how the printing industry changed. The lithographic process’s history is necessary to understand before reviewing the history of the ink, which is dependent on its use by lithographic printers and on the advances of technology over time.
2.2: History of Lithography
The development of lithographic inks cannot be discussed before first reviewing the history of the lithographic printmaking process. Alois Senefelder discovered lithography in 1796 in Bavaria. Senefelder was an actor, turned playwright, turned printer who had initially found interest in printing to more cheaply print theater plays. He had initially intended to use local Bavarian stone to create prints in an engraving method.[36] Through many experiments and only after many failed attempts, Senefelder instead discovered what we now know as lithography. Senefelder received a 15 year patent on the process in 1799 and spent the rest of his life promoting the lithographic printing process. His ventures in promoting his invention were fraught with false starts and temporary partnerships. Senefelder would find initial success with applying lithography to the reproduction of sheet music and printing of calico textiles, where the hand-drawn aspect of lithography worked well.[37] Senefelder wrote about the process in his publication Vollständiges Lehrbuch der Steindruckerey, which was published in 1818, which explained the printing method and contained the recipes he used.
The 1830s saw the emergence of chromolithography. Senefelder had experimented with color printing in lithography early on, producing some colored prints in 1809. Others would produce early color lithographs as well.[38] However, printer Godefroy Englemann detailed the chromolithographic process in 1837, creating a registration system and using the primary colors to build a complete chromatic range.[39] English lithographer Charles Joseph Hullmandel created another chromolithographic method in 1839 by using layers of color tints instead of the primary color method.[40] Chromolithography uses multiple stones to create layers of colors, varying from four to a dozen layers, typically including a black layer to add shade and contrast. By the 1850s chromolithography was being utilized as a cheaper method to create mass printed media. However, due to chromolithography’s beginning in the printing industry, it was not easily available for individual artist use. Initially, it had a negative association as something used only for art reproductions rather than original works.[41] It isn’t until the late 19th century that artists began to utilize lithography more frequently to create printed imagery. An 1881 change in French law on the posting of poster advertisements, alongside the lithographic process's artistic capabilities, led to the acceptance of chromolithographic posters as works of art worthy of collectors.[42] The sizes of lithographic advertisement posters also increased, some spanning 2 to 3 meters in length.[43] In the 1870s and 80s, many artist lithographs were done mostly in black and white, not embracing chromolithographs' full capabilities as advertisers were at the time. It was the 1890s and turn of the century when artists truly embraced color lithography, and when the print culture in France became it’s most popular and well known.
Around this time, the idea of the ‘painter-printmaker,’ visual artists who painted and made their own prints became popular.[44] Typically, artists would create an image and turn to master printmakers to create reproductions under their supervision as prints were often an essential method of making money for artists. This is true even today as visual artists will work with a master printmaker to create screenprints or lithographs for mass sales. This idea of artist-printmakers became popular at this time and would see fluctuating popularity in the future. In the cases where artists employed master printers for their editions, it is important to remember the printer and their expertise, which is often forgotten in favor of the artist.
With the onset of photography in the 19th century, it was only a matter of time before photosensitive materials made their way into printing and formed the beginnings of photolithography. To create a photolithograph, the lithographic stone is coated in a photosensitive material and exposed with a negative to light. The exposed areas harden and can accept ink while the unexposed areas wash away. Alongside the photolithographic printing was the creation of the collotype in the 1850s. By creating a photosensitive matrix with a dichromate-sensitive gelatine layer, a photo negative can be exposed onto the plate and treated to create a lithographic printing plate with a photographic image.[45]
While the popularity and techniques of direct lithography advanced, it was not the most widely used printing method. Lithography found its calling in producing sheet music, maps, and images, with few books being printed in a fully lithographic manner. Instead, typographic relief printing was much more suited to printing written material than lithography. This would change, however, with the development of offset lithography.[46]
The development of offset lithography came from a combination of inventions and improvements from various printing fields. The rotary press of 1843 was created to increase typographic print production but was soon adapted for the use of lithography with zinc plates. Almost as soon as stone lithography was introduced, Senefelder and many who later adapted to lithography had started experimenting with zinc plates and aluminum plates, as substitutes for the heavy lithographic stones. In the case of offset lithography, the benefit of using metal plates was not just their lightness but their ability to conform the plates into a cylinder for use on a rotary press. Before offset lithography was introduced for printing paper objects, Robert Barclay adapted the rotary press for the use of offset printing onto tin sheets in 1875 by using a roller covered in glazed cardboard as the offset roller.[47] In 1903, American printer Ira Washington Rubel had printed on a rotary press when a mistake in feeding paper into the press resulted in the inked plate offsetting onto a rubber roller before printing on the paper. The resulting print was found to have a better impression and without the rough texture that the plate would form when it came in contact with the printing paper. The technique of offset lithography was quickly picked up as it was cheaper and outperformed the direct flatbed lithography method, which lost its popularity after the 1930s.[48] One 1924 edition of the American National Lithographer stated it quite clearly, “Quite a number of high class type printing houses in this country have recently installed offset presses. They have discovered that with the offset lithograph press they can do better work for less money than they can possibly turn out with the old-fashioned flat bed type press...The offset press is living up to the prediction we made several years ago. Then we said that within ten years every lithographer in the country would be operating offset presses. That was less than ten years ago and to-day practically every lithographer has adopted the rubber blanket system of lithographing.”[49] The post-war period would bring about new changes in the printing field just as it had for many industries. One of the developments was the advent of the packaging industry in the 1950s, which would cause a new subset of industry in printing, particularly for offset lithography. Printing for packaging has become the highest demand for offset printing companies today, making up most of the printing industry’s clientele. Additional developments in printing technology in the 1950s would improve the publishing and magazine printing industry.[50]
Direct hand lithography was still in use by artists throughout the twentieth century, kept aloft by various print workshops catering to artists. However, it was not as popular as it once was at the turn of the century. In the United States, it wasn’t until the 1960s that a revival of lithography occurred amongst artists. Much of the credit for the revival is given to the establishment of Universal Limited Art Editions in Long Island by Tatyana Griseman in 1957 and the Tamarind Lithography Workshop by June Wayne in 1960.[51] These lithographic workshops acted to spread the interest in lithography to artists of the time. In the case of Tamarind, they trained many additional lithographic print masters who would go on to found their own print shops throughout North America. Tamarind would publish their own work on the lithographic process, The Tamarind Book of Lithography: Art & Techniques, in 1971. This publication and several others would all be published in the 1970s and become staple literature in many lithographic workshops.[52]
Today, direct lithography is still practiced by artists and master printmakers, with only some newspaper publishers still using the direct method to publish on a large scale.[53] The current direct lithographic workshops and university print studios can source their inks from various ink companies that specialize in hand lithographic ink and cater to this small printing community.
2.3: History of Lithographic Inks
As the creator of the process, Senefelder also made his own inks to go along with his new printing method. However, it should be noted that the ingredients or techniques that Senefelder used in creating inks were not novel or new. Much of Senefelder’s recipes and subsequent lithographic ink recipes in the 19th century had their foundation in the method of making relief and intaglio inks. To understand the reasoning behind Senefelder and other lithographic recipes, the history of relief and intaglio inks must be reviewed.
Oil-based relief inks have their own origins in oil paints, which became popular in the 15th century.[54] One of the earliest printing ink recipes we have comes from a manuscript dating from the 15th century and credited to a Flemish author and physician De Ketham.[55] This recipe was used for printing on textiles and mentioned some of the common practices that we see in later relief, intaglio, and lithographic printing inks. This includes the burning of linseed oil, resin use, the use of ink driers, and the use of a pigment very similar to what is later referred to as Frankfurt Black, created from burning vine branches.[56] Another early practice seen in relief and intaglio recipes is the practice of adding onion or bread into the burning oil. The method is mentioned in this intaglio ink recipe from 1645, “There are some who boyle an onion, or a crust of bread in the oyle, to render it (as they thinke) the less greasie.”[57] While the purpose and usefulness of this practice are often debated, recipes continue to cite it. Eventually, the practice is abandoned, but it is relevant here because it makes its way into early lithographic recipes.[58]
So while lithographic inks start with the beginning of the lithographic process, the steps that Senefelder lists in his ink recipes would have seemed familiar to contemporary ink makers. Senefelder recommended the creation of three different inks, each varying in thicknesses.[59] His inks were created using linseed oil, and the three levels of thickness were created by adjusting the burning time of the oil as the longer the oil was burned, the higher the viscosity.[60] Senefelder often allowed his linseed oil to catch fire and burn but also notes that allowing the linseed oil to boil without catching fire could create a clearer varnish with the detriment of taking longer to produce.[61] Senefelder uses lampblack for his pigment, and though he does not mention a qualitative amount that is needed, he advises not to add too much as it may cause what we know as scumming. While subsequent recipes are similar to the recommendations given by Senefelder, some follow a trend seen in the 19th-century lithographic ink recipes that include the use of wax and soap in ink. This is likely due to concerns with water-resistance of the ink. Wax continues to appear occasionally in lithographic ink recipes throughout the 1800s before falling out of use.[62] Philip Ruxton’s Printing inks in 1918 claims that soaps were used in lithographic inks in the early 19th-century, but we find that soap had sometimes been used in typographic inks in the 1700s.[63] Soap was added to typographic inks to create a sharper impression and thicken the ink so that the linseed oil used in the ink making process did not have to boil as long.[64] The inclusion of soap is likely a practice inherited from typographic ink practices.
The discovery of aniline dyes, starting with Perkin’s discovery of mauve in 1856, lead to new colorants being added to lithographic inks. Aniline is an extract of coal tar, and the dyes are sometimes named coal tar dyes in early literature. What started as a few dyes for textiles soon became many and began to be applied to other industries.[65] The dyes were often precipitated and made into solid lakes to be used in printing inks. The lake dyes’ fugitive nature in textiles was seen very quickly; the same occurrence was tested and seen in printing inks in 1914.[66] One source from 1924 notes that “The most fugitive colours are as follows: the methyl violet lakes, the coal-tar green lakes, and some aniline reds of the eosine series.”[67]
Beyond the new colorants created from the aniline dye industry, ink recipes for lithographic inks had changed little up until the first synthetic resins were introduced in the 1920s.[68] Profound changes to ink recipes would occur in the postwar era of the late 1940s, with the petrochemical industry’s development leading to many new pigments, polymers, solvents, and additives being produced.[69] Many of the synthetic resins we see in modern ink manufacturing found their origin in the mid-century post-war period.[70] This trend towards synthetics continued until the 1990s brought with it a flood of environmental concerns about the ink manufacturing process and products and has since led to the development of many water-based and soy-based printing inks.
However, it is important to note that many of the lithographic ink recipes’ changes after the 1910s were reserved for the offset lithographic inks and typographic inks which were in high demand by industrial printing companies. The story of hand lithographic inks become buried by the developments of its offset cousin. Due to its smaller demand, ink manufacturers did not often cater to hand lithographic printers. Staff and Sacilotto comment on the industry’s preference for offset inks in their Printmaking: History and Process of 1978 and advise on using and modifying to offset inks for hand printing. Artists at the time were advised to purchase offset inks without drivers or to modify offset inks with the use of transparent white to extend the ink and gain the desired intensity of colored ink.[71] Though this advice was given in the 1970s, any printers using direct lithography in the early 20th century likely used similarly self-modified inks.
As the interest in direct lithography returned in the 1960s and 70s we began to see evidence of ink manufacturers collaborating with artists and lithographic print studios, as mentioned in the Tamarind studio publication.[72] Tamarind collaborated with the Sinclair & Valentine Ink Company in 1960 to create lithographic inks that were ideal for use in direct hand lithography and encouraged other potential collaborations between printers and ink manufacturers. Since then, modern industry publications on printing inks still typically omit direct lithography all together, usually mentioning it in a historical context but otherwise only discussing the qualities of offset lithographic inks.[73] Despite this, some printing companies now specialize in creating printing inks for print artists that work in lithography.
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