The "litho" behind lithography
- Irene Michnicki
- 3 hours ago
- 10 min read
A deep dive into the geology and quarrying history of Solnhofen limestone, and why no other stone on earth has ever quite replaced it for the lithographic process.
"Lithos": a Greek word meaning stone or rock
— from the Merriam-Webster Dictionary
When you work on a lithographic limestone, you're interacting with a piece of the Jurassic sea floor. The surface under your fingertips settled out of warm, shallow water roughly 150 million years ago, particle by microscopic particle, in a network of calm lagoons in what is now southern Bavaria. The fact that this ancient sedimentary rock turns out to be the ideal material for holding a drawn image and transferring it to paper is one of those accidents of geology and science that printmakers have been grateful for ever since Alois Senefelder discovered it in the 1790s.
This is the story of that stone: where it comes from, how it's been quarried, why it works so well, and what limestone quarrying looks like today.
A Jurassic sea floor in Southern Bavaria
The Altmühl River Valley lies in the Franconian Alb region of Bavaria, roughly halfway between Nuremberg and Munich. It's quiet country, with rolling hills, small farms, traditional stone-roofed houses called Jurahaus. On the surface, there isn't too much evidence to suggest that it sits atop one of the most geologically distinctive formations in Europe. The limestone here, known as the Solnhofen Plattenkalk, is an Upper Jurassic deposit laid down between roughly 153 and 148 million years ago.
At that time, the area was covered by a shallow, warm, tropical sea dotted with islands and sheltered lagoons, protected from the open ocean by barriers of coral and sponge reefs. The water in those lagoons was largely still, with very little oxygen near the bottom and, scientists believe, unusually high salinity. Fine carbonate mud drifted down through the water column and settled undisturbed on the lagoon floors, accumulating in thin, even layers over millions of years. Temperatures were also very consistent and prevented any recrystallization from occurring. This is a geological process involving heat and pressure that would have completely changed the stone from sedimentary to metamorphic, or limestone to marble. The conditions that made those waters hostile to life are exactly what made the limestone they produced so useful. An almost perfectly homogeneous accumulation of microscopic calcium carbonate particles, compressed over geological time into flat, dense, consistent stone.
The Plattenkalk
The German word Plattenkalk means "slab limestone," which describes the stone's most distinctive physical quality: it naturally splits into flat, even sheets along its bedding planes, without the need for sawing. This property made it useful for building long before anyone thought of printing on it.
The formation also preserved, with extraordinary fidelity, the creatures that fell into those lagoons and died. The Solnhofen quarries have produced some of the most famous fossils in the world, including multiple specimens of Archaeopteryx, the feathered early bird whose formal name, Archaeopteryx lithographica, is a direct tribute to the stone that preserved it and the printing industry that caused it to be found.
Centuries of quarrying
The Solnhofen Plattenkalk has been quarried since the Stone Age, and the Romans used it for tile. For most of its history, the stone's value was architectural: it splits cleanly into flat sheets that make excellent floor tiles, wall cladding, and roofing material. The gently pitched stone roofs of traditional Jurahaus farmhouses across the Franconian Alb are a living monument to this older use of the stone. Solnhofen limestone covered the floors of Bavarian churches and castles, and was exported along the Danube as far as Austria and Hungary from at least the sixteenth century.
All of that changed after 1796, when a man who was living in nearby Ingolstadt at the time named Alois Senefelder invented lithography using locally available stone. We've written another blog post about Alois Senefelder and the process & history of lithography. Click the link to learn more.
Once the printing world understood what Solnhofen limestone could do, demand for the finest grades of stone exploded. The quarrying district expanded rapidly through the nineteenth century, a railroad reached Solnhofen specifically to serve the stone trade, and the region became the global headquarters of the lithographic supply industry. It's not an overstatement to say that the art and commercial printing of the entire nineteenth century ran, quite literally, on stone pulled from this small stretch of Bavarian farmland. The species name Archaeopteryx lithographica, coined in 1861, is as much a monument to that industry as it is to the bird itself: the fossil was found because quarrymen were mining limestone for printing presses.
The quarrying district stretches roughly 40 kilometers across a region in Germany called the Franconian Alb, with the main production areas concentrated around Solnhofen, Eichstätt, Mörnsheim, and Langenaltheim. Extraction has always been done by hand, using wedges and splitting tools to lift sheets cleanly from the rock face along natural bedding planes. This gentle method, largely unchanged for centuries, is also what has allowed so many fossils to survive intact. This same care in extraction that protects the stone slabs for lithographic use also help keep something like a 150-million-year-old feather intact for scientists to study.
Why the stone works: Geology meets printmaking
Limestone exists on every continent, and generations of printers have spent two centuries trying to find local alternatives to importing limestone from Germany. Stone from France, China, Kentucky, Iowa, Tennessee, and elsewhere has been tested, quarried, and shipped to studios. Some of it has been useful. None has fully replaced Solnhofen, and the reason comes down to something that happened in those Jurassic lagoons 150 million years ago.
The Solnhofen Plattenkalk is made from micritic limestone, a type built from calcium carbonate particles so fine they are invisible to the naked eye. Most limestone in the world contains coarser material: shell fragments, recrystallized minerals, skeletal debris. The limestone deposits in this region formed in calm and chemically stable conditions that never allowed coarser particles to develop, and early recrystallization was prevented, permanently locking in the original fine-grained structure. The result is a stone of unique consistency at a microscopic level, not just smooth in surface, but uniformly smooth in it's content: mostly calcium carbonate with very little impurities.
A note on fossils and inclusions in litho stones
There are occasionally quartz and iron deposits and small fossils in stones deemed for lithographic use and when graining to resurface the stone for a new image, they may show up in specific layers. Iron deposits generally don't cause problems and just appear as reddish-brown tinted areas of the stone. Quartz can be a little trickier; it usually presents itself as a line of quartz and can resist grease and ink because of its chemistry and relative hardness causing a line or spot to be blank through a print. The fossils in litho stones won't be like the larger Archaeopteryx fossil mentioned before, or like the
many sizable fossils that have been found in Solnhofen limestone from sea and land dwelling creatures.
Typical stones and areas of the quarries designated for lithographic use might sometimes include fossils created by very tiny sea invertebrates that appear as little white dots instead of fully formed skeletal structures. The little white fossils normally resist the grease of lithographic drawing materials and printing ink, so they are not desirable if you are trying for the most precise image. However, it's still pretty cool to see them pop up once in a while and really brings you back in connection to limestone as a pre-historic material with unique chemical qualities.
For printmaking and the process of lithography, the lack of impurities and fine grain structure matter in two ways. First, the surface responds to drawing materials with unmatched sensitivity. A lithographic crayon dragged across Solnhofen stone deposits grease and pigment in patterns that precisely follow the micro-texture of the surface, producing tonal gradations from light grey to deep velvety black that coarser stones don't replicate as faithfully. The drawn image has a direct translation through the stone that you can see in the finished print. Second, the stone's extremely low porosity means it holds the moisture barrier that lithography depends on with consistency: dampened just enough to repel the oily ink from blank areas, no more, no less, impression after impression.
Solnhofen's competition: Other stones and surfaces
The most serious challengers to Solnhofen limestone have come from France and the state of Kentucky and Iowa in the United States. Quarries near Le Vigan in the Gard region of southern France exhibited their stone at the Great Exhibition of 1851, where it earned an honorable mention; the largest lithographic stone ever quarried, measuring 230 by 150 centimeters, came from that area. In the United States, a quarry at Brandenburg, Kentucky operated as the only commercial American source of lithographic stone at the turn of the twentieth century, and dramatically scaled up production in 1916 and 1917 when World War I cut off access to German imports. In 1903, a deposit was discovered near Orchard, Iowa. The location was optimistically crowned as "Lithograph City" and a company geologist reported the stone to be finer-grained than the finest Solnhofen material.
Beyond limestone entirely, printmakers have also experimented with other calcium carbonate based stones: marble and onyx. One of the more promising alternatives to limestone explored was Pedrara onyx, a calcareous variety, that is quarried in Baja California, Mexico.
In the Tamarind Technical Papers document Vol. 1, Number 4 from July of 1975, Clinton Adams speaks about the experiments conducted by master printer Stephen Britko, who found Pedrara onyx capable as a printing element. Calcareous onyx shares a broadly similar chemical composition to Solnhofen limestone, both being predominantly calcium carbonate in important ways: onyx is harder, has a crystalline rather than micritic calcite structure, and is more translucent rather than opaque. Its extremely close grain and near-impermeability to staining were noted as strengths.
Britko found that it accepted crayon and tusche drawings well, withstood the pressure of a lithogaphy press when backed with slate, and produced excellent impressions. He concluded it required stronger etches than most limestone because of its hardness and that tusche washes worked best with a relatively low grease content. Senefelder himself had noted in his original writings that various marbles could be used for lithography, though he maintained that Solnhofen stone would retain its advantage because of its light color and, at that time, its availability and cheaper price. That cost advantage no longer holds in the same way, and as newly quarried and prepared Bavarian limestone at the highest qualities is becoming more scarce and expensive, alternatives like Pedrara onyx still remain of real interest to printmakers love the art form and are willing to adapt.
La Ceiba Gráfica is a wonderful example of a printmaking center and institution using Mexican onyx for lithographic printing in their studios instead of German limestone. Located in the Veracruz region of Mexico, they offer workshops in lithography and various printmaking techniques and value sustainable materials that have a cultural and geographic link. Using onyx slabs sourced from Mexico is a core component of La Ceiba Gráfica's practice and mission.
Bavarian limestone: Is there an alternative?
None of these sources have ultimately displaced Bavarian limestone in the practice of stone lithography. The particular combination of grain size, chemical composition, porosity, and structural homogeneity that makes Solnhofen stone so effective appears to be a product of a specific natural and geological environment that has no close modern equivalent anywhere on earth.
The Solnhofen quarries today
Active quarrying of lithographic-grade stone continues in the Solnhofen region, though on a much smaller scale than the industry's nineteenth-century peak. The primary operation today is the SSG Solnhofen Stone Group, which describes itself as having over 150 years of continuous quarrying experience and operates multiple facilities and quarries in the region. SSG markets lithographic-grade stone specifically to fine art printmakers under the name Lithostone, and states that all lithographic limestone in use worldwide today originates from their operation.
Elsewhere in the quarrying district, smaller family-run operations continue extracting stone largely by hand, splitting slabs from the rock face using traditional tools during the summer quarrying season, much as quarrymen have done for centuries. The stone is still exported globally, though the volumes destined for printmaking are a fraction of what they once were. Most of what comes out of the ground today goes to architectural flooring, wall decoration, and historic restoration: for the same purposes the stone served before Senefelder ever picked up a grease pencil and made his discovery.
The finest grades of lithographic stone are the thick, dense, blue-grey slabs quarried around Mörnsheim. These are becoming more scarce, and their price reflects it. Many of the richest deposits have been exhausted, and the remaining stone requires increasingly careful extraction to find layers of sufficient quality and thickness for printing use. Studios and print shops that work in stone lithography treat their slabs accordingly with proper storage techniques, re-graining and backing exceptional slabs of stone when they get too thin in order to continue using them across many editions over years or decades. A stone in use at Milestone Graphics today may have held images by artists we admire, and will hold images by artists not yet working. That history is part of what you're working with when you draw on Bavarian limestone.
Limestone: A living connection
The town of Solnhofen itself commemorates all of this with a statue of Alois Senefelder and the Bürgermeister-Müller-Museum which is dedicated jointly to the history of lithography and the paleontological discoveries the quarries have yielded. It's a fitting combination: the same stone, the same hand-splitting method, the same careful attention to what lies within the rock. The quarrying of lithographic limestone and the discovery of Archaeopteryx are part of the same story.
If you'd like to see what this material looks like in use, or to work with it yourself, we'd love to have you visit the studio. Milestone Graphics is always happy to talk lithography: stone, chemistry, geology, printing, or all of the above.
Sources
Wikipedia: Solnhofen Limestone. en.wikipedia.org/wiki/Solnhofen_Limestone
Encyclopaedia Britannica: Solnhofen Limestone. britannica.com/science/Solnhofen-Limestone
UC Museum of Paleontology, Berkeley (on Archaeopteryx lithographica). https://ucmp.berkeley.edu/diapsids/birds/archaeopteryx.html
Lauer Foundation for Paleontology: Solnhofen Fossils (on Romans using limestone for tile). lauerfoundationpse.org/solnhofen-fossils
IUGS Geoheritage: Solnhofen Limestone. iugs-geoheritage.org/geoheritage_stones/solnhofen-limestone
Association of European Printing Museums: Invention of Lithography and the Solnhofen Quarries. aepm.eu
Geological Society of London / Scilit: Solnhofener Plattenkalk: a heritage stone of international significance from Germany. scilit.com
Barnhoorn et al.: Texture development during coaxial and non-coaxial deformation of a calcite rock, Journal of Structural Geology (ScienceDirect). Documents average grain size of ~4 μm via SEM and EBSD analysis. sciencedirect.com
Schweizerbart Science Publishers: Sedimentological and petrophysical characteristics of Solnhofen monument stones. schweizerbart.de
Wikipedia: Lithographic Limestone (on Le Vigan, Brandenburg, Iowa). en.wikipedia.org/wiki/Lithographic_limestone
Polymetaal, André Beguin, A Technical Dictionary of Printmaking. lithography, definition and historical outline, on stones from Le Vigan in France. https://www.polymetaal.nl/beguin/mapl/lithography/lithomater.htm
https://books.google.com/books?id=dvjNAAAAMAAJ&pg=RA1-PA28#v=onepage&q&f=false
https://www.polymetaal.nl/beguin/mapl/lithography/lithomater.htm
SSG Solnhofen Stone Group: Lithostone and Company. ssg-solnhofen.de/en/products/lithostone
SoNat Natural Stones: Solnhofener Natural Stone. sonat.de/en/select/solnhofener-naturstein
Vernon A. Clark: The Solnhofen Quarries, Tamarind Technical Papers, Vol. 1, No. 4 (July 1975). Tamarind Institute, University of New Mexico. A firsthand account of the Aktein-Verein quarry operations as observed in 1975; details of current practice may differ. digitalrepository.unm.edu/tamarind_papers/vol1/iss4/1
Clinton Adams: Pedrara Onyx: Its Use in Lithography, Tamarind Technical Papers, Vol. 1, No. 4 (July 1975). Tamarind Institute, University of New Mexico. A firsthand account of the Aktein-Verein quarry operations as observed in 1975; details of current practice may differ. digitalrepository.unm.edu/tamarind_papers/vol1/iss4/1
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