In a multi-block print, one block usually holds the drawing: the outlines, the detail, the lines that tell you what you are looking at. That is the key block. The other blocks hold colour, and they are shaped to fit around it.
The word "key" is doing real work there. It is not just the most important block — it is the one the others are keyed to. Every colour block is cut from an impression pulled off the key block, so all of them inherit one drawing rather than each being traced separately and drifting apart.
Cut first. Printed — that depends.
On the carving order every source agrees, and the agreement is not a matter of taste. The key block is cut first because the colour blocks are made from it. You cannot derive something from a block that does not exist yet.
The printing order is a different question, and here the accounts genuinely disagree.
The case for printing it first
Put the outlines down first and every colour block that follows can be checked against them immediately. If a colour lands two millimetres out, you see it on the first sheet and can correct it before you have wasted a batch. Traditional Japanese practice generally worked this way, and it works because the pigments were nearly always transparent: colour printed over black lines does not bury them.
The case for printing it last
Opaque ink is the whole problem. A dark, opaque colour laid over a fine black line simply swallows it, and the drawing you cut so carefully disappears under a flat mass. If your inks are opaque — which most Western relief inks are unless you extend them — the key block has to go on top, and a good deal of contemporary Western practice does exactly that.
The cost is that you lose your check. You are printing every colour block blind, with nothing to register against until the very last pass. The traditional answer to that is neat: on the first few sheets of each batch, pull a faint impression of the key block first, purely to verify that the colour has landed correctly, then set those aside and run the rest of the batch without it.
Not tradition. Ink opacity. Transparent ink lets you print the key block first and check as you go. Opaque ink forces it last and forces you to test.
Which means the decision belongs to whoever is mixing the ink, and it should be made before the first block is cut — not discovered at the press.
There is a third option, and it is a good one. Print the key block first in a pale, unobtrusive colour that will vanish under the finished print — a thin brown, say. It does no work in the final image at all; it exists purely to place the colours accurately. Any dark outline you actually want in the print is then cut and printed as a colour block, last. Yoshida used precisely this on at least one print.
Do you need one at all?
Often, no. A great many good multi-block prints have no key block, and their colour shapes do all the work of describing the subject. A key block costs you an entire extra block, an extra printing, and an extra registration to get wrong. It is not a requirement of multi-block printing — it is one approach to it.
The alternative is cumulative: cut your first block, pull an impression from it, use that impression to lay out the second block, print the second over the first, and use that to lay out the third. Each block is positioned from what is already printed rather than from a single master. This is common in Western practice, and it is worth naming what you are trading. With a key block, every block descends from one drawing and errors do not accumulate. Without one, each block inherits the small inaccuracies of everything before it.
Reduction printing sidesteps the question entirely, since there is only ever one block.
Making one: the drawing
A key block wants outlines and essential detail, nothing else. No shading, no tone, no indication of colour — that is what the other blocks are for. If you are working from a photograph or a tonal drawing, the job is to strip it back to line.
The hard part is that a drawn line and a cuttable line are not the same object. On paper a line has no width worth thinking about. On a block it is a physical ridge of lino or wood standing above a cleared field, and if it is too thin it will crumble under the gouge, break off on the press, or refuse to hold ink evenly. Every line in a key block has to be wide enough to survive being a solid object.
There is no published figure for how thin a line of lino can be and still survive. The thresholds used in these tools are my own, and material matters a great deal — soft carving blocks and grey battleship lino do not behave the same way. Treat any warning as a prompt to look, not a verdict.
Two practical consequences. Thicken lines deliberately rather than hoping; a line that reads as delicate on screen is usually the one that fails. And where two lines run close together, check the gap as well as the lines — a sliver of cleared material between two ridges is just as fragile, and picks up ink it should not.
Making one: getting it onto the block
Whichever method you use, remember that the block prints in reverse. The drawing goes onto the block mirrored, or the print comes out mirrored — and text especially will humiliate you here.
The Japanese method
The outline drawing — the hanshita — is made on thin paper, and it carries the registration marks as well as the design. It is pasted face down onto the block, so the drawing is automatically reversed, and the carver cuts straight through the paper, following the lines from the back. The kento marks are cut at the same time, in the same operation, as part of the same drawing. That is the point: the drawing and the registration are established together and cannot drift apart.
The lino method
Same principle, cruder means. Trace the drawing onto tracing paper, flip it, and go over the back to transfer it — a soft pencil rubbed on the reverse works, as does carbon paper. Or print your drawing out reversed and transfer it. Whichever you use, put the registration marks on the same transfer as the drawing, and put them on before anything is cut. Adding registration afterwards, by eye, undoes most of the benefit of having a key block in the first place.
Using it to place the colour blocks
This is the part most people have never been told exists, and it is the strongest argument for cutting a key block at all.
Once the key block is finished, print as many impressions from it as you have colours, plus a few spares. These impressions are called kyōgō. Each one gets pasted face down onto a blank block, and that colour block is then cut by removing everything that is not that colour. Every block in the set now carries the same drawing, from the same source, at the same size.
These impressions are not printed normally. Do not put the paper into the kento. Lay the sheet over the whole block and take ink or pigment across everything — including the registration marks themselves.
That is the entire trick. The marks print onto the sheet, so when the sheet is pasted onto a colour block you can see exactly where that block's kento must be cut. Register the paper normally and the marks never transfer, and you are back to positioning them by eye.
Three practical cautions, all learned expensively by people before us:
- Pull them all in one session. Not across two days. Conditions change, the paper changes, and the impressions stop matching each other.
- Do not over-wet the block. Too much moisture and the impression dries shrunken — which means every colour block cut from it is slightly the wrong size.
- Mind fresh wood. If you paste impressions onto newly prepared blocks, the wood shrinks as it continues to dry and pulls the drawing out of register with the key block. Let it settle first.
One consolation: the colour blocks do not need the precision the key block does. Their edges hide under outlines and under each other. It is the key block that has to be right.
Block Plate takes a photograph or a drawing and reduces it to flat black and white — which is a key block, essentially. Its sliver warnings measure at your real print size and flag the lines too thin to survive and the gaps too narrow to clear.
Kento works out the registration itself, and its printable template is what you want alongside the drawing when you mark the block up.
Neither will separate an image into colour blocks for you. That is Reduction Ladder's job, and it does not currently generate a key block to go over the top — you would run the two tools on the same image.
Where this comes from
- Dave Bull, "Two streams…", Encyclopedia of Woodblock Printmaking — the carving sequence, kento cut with the design, and the crucial detail that kyōgō impressions are taken over the whole block with the registration marks inked, not into the kento.
- Hiroshi Yoshida, Japanese Wood-block Printing (1939), chapters III and IV, via woodblock.com — colours-first-outline-last as a known but troublesome method; the pale key block printed purely to place colour; the instruction to pull all impressions in one session; and the account of the Western method that dispenses with a key block entirely.
- F. Morley Fletcher, Wood-block Printing, via woodblock.com — key block cut first as the rule; the faint test impression when it must be printed last; register marks inked into the impressions; and the shrinkage of fresh wood pulling colour blocks out of register.
- "The Production of Japanese Woodblock Prints" — surviving prints show the key block was often not printed first, because dark colours obliterate fine black lines.
- Daily Art Magazine, "How Japanese Woodcuts Were Made" — the sen-gaki and iro-sashi stages, and the warning about over-wetting producing a shrunken kyōgō.
- Tom Killion, "Tom's Technique" — a working contemporary account of printing the key block last, and of keeping key blocks after the colour blocks are cancelled.
- The transfer methods described for lino — tracing paper, carbon, reversed printout — are ordinary workshop practice rather than anything I found published. The sliver thresholds mentioned are my own and are not evidence-based; see Turning a photograph into a carve-ready block.