You do not need to be a printer to look at a Thomé plate and understand why 1885 still holds up. But you do need a handful of words, because most of what is written online about "how botanical plates were printed" collapses three different centuries of technology into one vague sentence about "old lithographs." It is not one thing. The 1885 chromolithograph of *Matricaria chamomilla* in *Flora von Deutschland, Österreich und der Schweiz* was made by a specific process, with a specific hand, on a specific kind of limestone. The terms below are the minimum vocabulary to see it.
The Stone
Chromolithography starts with a rock. Specifically, a slab of fine-grained Bavarian limestone from the quarries around Solnhofen — the same beds that later gave palaeontologists the Solnhofen *Archaeopteryx*. The stone is porous in a very particular way: it accepts grease where you draw and holds water everywhere else, which is the entire chemical basis of lithography. For a plate like Thomé's *Hedera helix*, the printer is not choosing a stone the way a painter chooses a canvas. Each colour in the final image requires its own stone, ground flat to a matte tooth with abrasive and water, then dried and stored under cover so no dust or fingerprint contaminates the surface before the artist touches it. A working printshop in 1885 held hundreds of these slabs, some weighing over a hundred kilos, stacked like library folios. When a run ended, the surface was ground down and the stone reused. Almost none of the original drawing stones from that period survive. The prints are what remain.
The Key Drawing
Before any colour is separated, the printer or their draughtsman lays down what is called the key: the black or dark-brown line drawing that carries the plant's architecture — the leaf margins, the vein structure, the outline of every floret. On a Thomé plate of *Foeniculum vulgare*, the key is what tells your eye that the umbel has this many rays and that each ray terminates in these many flowers. The key is drawn directly onto its own stone using a greasy crayon or a pen loaded with lithographic tusche — an oily ink that binds to the limestone at a molecular level. Everything that follows, every wash of green, every accent of yellow at the anther, is registered against this drawing. If the key is wrong, the plant is wrong, no matter how good the colour work is. This is why the illustrator's name — Thomé, in our case — attaches to the key stone, even when a workshop of anonymous chromists did the colours.
The Colour Separation
Here is where chromolithography earns its name and where the modern reader almost always misunderstands. There is no CMYK. There is no four-colour process in the sense your inkjet uses. Each colour in the finished plate is a distinct ink, drawn on a distinct stone, printed as a distinct pass. A Thomé plate of *Centaurea cyanus* — cornflower blue — might use eight, ten, twelve separate stones: one for the cornflower's specific saturated blue, another for the paler blue in shadow, another for the stem's cool green, another for the yellow-green of the leaf midrib, another for the brown of the receptacle, another for the neutral grey that models the leaf underside. Each stone corresponds to one area of one colour. A chromist studied a watercolour original or the plant itself and mentally decomposed it into these layers, then drew each layer separately, in reverse, on its own stone. The intelligence of the process lives at this stage. A weak separation makes a muddy print. A brilliant separation makes a plate that still looks luminous on a wall in 2026.
Cornflower
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The Registration Cross
If you print ten colours on ten different stones, each requires a way to line up perfectly with the others. That is the registration cross: a small crosshair mark, usually printed off in the margin, sometimes in a corner outside the image, that the printer aligns by eye at the start of every pass. Miss it by half a millimetre and the cornflower's blue drifts off its petal onto white paper. Miss it by two millimetres and the plate looks drunk. Registration is why chromolithography was, above all, a craft of the hand and the eye at the press. A pressman working on the *Chamomilla* plate would run the paper through, inspect the cross, adjust the sheet minutely, ink the next stone, and pull again. In our restoration work at the studio, one of the tells that separates a first-run 1885 impression from a later reprint is how tight the registration is. Sharp registration is expensive. Loose registration is what happens when the workshop is tired.
The Proof Pull
Before committing to a full run of hundreds or thousands of copies, the printer pulls a proof: a single trial impression of the plate, colour by colour, checked against the artist's original or the workshop's colour bon-à-tirer — the "good to print" reference sheet. On a Thomé plate, the proof would come off the press and go to the botanical editor, who checked whether the *Hedera helix* leaf's exact shade of matte dark green matched the plant. If it did not, an ink was reformulated, a stone was retouched, another proof pulled. A ten-stone plate might absorb dozens of proofs before the printer was cleared to run production. Proofs are where the historical record of decision-making lives. Institutional archives occasionally hold Thomé-era proof sheets with pencil annotations in the margins — "grün zu blau" (green too blue), "Vein hard" — and reading them is the closest thing we have to standing inside the workshop.
The Ink Grease
The reason chromolithography works chemically is a very old truth: oil and water do not mix. The greasy tusche you drew with binds to the limestone and repels water. When the pressman dampens the stone with a sponge, water sits everywhere except where the drawing is. When they roll oil-based ink across the stone, the ink refuses the wet areas and adheres only to the greasy drawing. Paper pressed down under the scraper of the press then lifts the ink cleanly. Every colour ink in a chromolithograph was formulated in-house — pigment ground in linseed oil to a specific viscosity, tested for opacity and lightfastness. Blues came from Prussian blue or ultramarine, greens from mixtures or from arsenic-based emeralds that we now know are dangerous. The 1885 *Cornflower* plate holds its blue not because of digital colour management but because a workshop chemist knew which pigment would not fade under a hundred and forty years of parlour light. Most of them were right.
The Press Run
A production run of a botanical plate for a scholarly work like *Flora von Deutschland, Österreich und der Schweiz* meant that every sheet passed under the press once per colour. For a ten-stone plate at, say, an edition of two thousand copies, that is twenty thousand press pulls, sheet by sheet, colour by colour, over the course of days or weeks. The presses were flatbed hand-operated cylinders, later steam-powered, with a leather-covered scraper that dragged across the stone under pressure to transfer the ink. Between passes, printed sheets hung to dry on racks so an underlying ink was set before the next colour landed on top. In a working chromolithographic shop the ceiling looked like a hayloft of drying botanical prints. This is also why chromolithographs have a distinct physical presence: the sequential layering of thick opaque inks builds up a slight, palpable relief on the paper. Run your fingertip across an authentic Thomé plate at a raking light and you can almost feel the colour history.
The Halftone Rival
By the time Thomé's *Flora* was going through its expanded editions, the technology that would eventually kill chromolithography was already in the room. The halftone process — photographing a subject through a screen that broke tone into a grid of tiny black dots — arrived commercially in the 1880s and 1890s. It could reproduce a watercolour or a photograph mechanically, without a chromist, without ten stones, without a registration cross. Halftone was faster, cheaper, and, for photographic subjects, more literal. What it could not do, for a long time, was equal the deep saturated colour and the drawn clarity of a well-made chromolithograph. A halftone reproduction of a *Matricaria chamomilla* plate has to break the yellow disc and the white ray florets into a screen of dots; you see the grid if you lean in. A chromolithograph lays down continuous flat areas of the actual pigment. This is the single technical reason a first-edition Thomé plate looks better on a wall than a mid-twentieth-century magazine reproduction of the same image. The halftone was a different animal.
The Digital Restoration
Everything we do at the studio in 2026 is downstream of these nineteenth-century decisions. A high-resolution scan of a surviving 1885 plate of *Foeniculum vulgare* captures the ink layers, the paper foxing, the tiny registration drifts, the sun-fade at the top edge where the volume sat open in some previous century's library. Restoration means separating what is the printer's intention from what is a hundred and forty years of accident: lifting yellowed acidic paper stain back toward the original white, closing tears without redrawing lines, colour-correcting away the shift caused by pigment aging, sharpening the key without introducing artefacts that were never there. The one rule we hold to is that we do not invent. If a corner of the *Hedera helix* leaf is missing on every surviving impression, we leave it missing. What we restore is what the workshop printed. What we do not do is repaint the plate to match what we imagine 1885 wished it looked like. That is a different kind of picture and a different kind of business.
What none of the above tells you is how a single restored plate should live on a wall — how it should be sized, spaced, matted, or grouped with others. That is the question the terms above make possible, and it is where the next piece of work begins.
FAQ
Is a chromolithograph the same thing as a lithograph?
No. A lithograph is a single-colour print from one drawing stone — often black ink on white paper, or a single tinted layer. A chromolithograph is a lithograph made in colour by printing multiple stones in sequence, one per colour. Every chromolithograph is a lithograph in technique, but the word "chromo" specifically flags that colour was built up through separations and registration rather than added by hand after printing. Thomé's 1885 plates are chromolithographs.
Were the colours in Thomé's Flora hand-painted?
No. That is a common misconception born of the earlier tradition of hand-coloured engravings, where a black-and-white print was tinted by a colourist with a brush. In a chromolithograph, every colour is printed. There is no watercolour added afterwards. The saturated blue of a *Centaurea cyanus* plate came off a stone through a press, not off a brush. Occasional workshops added a spot of hand-finishing on luxury editions, but the *Flora von Deutschland* colour was printed.
Why do 1885 prints often look better than modern reproductions?
Because a chromolithograph lays down continuous flat areas of the actual pigment the printer chose, while a modern offset or inkjet reproduction breaks colour into a screen of dots or droplets that only simulate the tone. At normal viewing distance the eye reads the older process as denser, more luminous, and more physically present. This is not nostalgia — it is a straightforward optical difference between layered opaque ink and screened translucent ink.
What happened to the original limestone printing stones?
Almost all were ground down and reused. A working nineteenth-century printshop treated stones as consumable inventory: once a run ended, the surface of each stone was reground flat, erasing the drawing, and the slab was returned to circulation for the next job. A very small number of drawing stones survived by accident in museum collections. This is why the plates themselves — the printed sheets — are what carry the history now.
How can you tell a first-edition Thomé plate from a later reprint?
The tells are cumulative rather than single. Paper weight and texture, the tightness of colour registration, the depth of ink layering, watermarks in the sheet, the specific typography of any caption, and the way the pigments have aged all contribute. A specialist reading a batch of impressions of the same *Matricaria chamomilla* plate can usually sort them by decade. For anyone outside that specialism, the honest answer is that authoritative attribution requires physical inspection, not a JPEG.
Was chromolithography a German invention?
The core lithographic process was invented in Bavaria by Alois Senefelder around 1796, and the multi-stone colour variant developed across the German-speaking world and France through the nineteenth century. By the time Thomé's *Flora* was in production, German printshops were among the most technically accomplished in Europe. Attributing "chromolithography" to any single national tradition understates how much traffic there was between Munich, Paris and Vienna. But Bavarian limestone was the physical foundation of the craft.
Are the pigments in a Thomé plate safe to handle?
Most are, but not all. Nineteenth-century printers used pigments that included arsenic-based greens, lead-based whites, and mercury-based reds. In a bound volume kept in normal handling these present no meaningful exposure, but a restorer working with a damaged or flaking impression treats the surface with basic precautions — gloves, no ingestion, controlled ventilation when cleaning. The restored digital files we work from carry none of this, which is one of the quiet advantages of moving the plate into the twenty-first century without losing what the printer put down in the nineteenth.
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