Job 03Ink4 sections7 min

Mixing ink by eye, and the swatch book that saves me

I have never weighed ink. Everything that comes off this press is mixed on a glass slab with a palette knife and judged by eye, which works perfectly well right up until somebody asks for the same colour a second time.

First pull: 22 March 2025
Last revised: 30 May 2025
Room: Vilnius, Lithuania

The slab, the knife, and how little you need

The first thing anybody prints is too dark, too thick and slightly smeared, and the cause is almost always the same: far more ink than the job needs. A teaspoon will ink a hundred postcard-sized sheets with room to spare. What goes on the slab should look like an insufficient amount, spread into a film you could read a newspaper through, and if the roller sounds sticky rather than hissing there is too much on it. Three light passes beat one loaded pass in every way that matters.

My slab is a square of plate glass off an old table with the edges ground, sitting on a sheet of white paper so that I can see the colour honestly. The knife matters less than people say, as long as it is flexible and long enough to lift a whole ribbon of ink at once. Mixing is folding rather than stirring: lift, turn over, press down, drag out flat, repeat until no marbling shows when you scrape a thin window across the glass. Marbling means streaks on the sheet, and streaks appear on the fifth print rather than the first.

From the make-ready sheet

A teaspoon of ink covers a hundred small sheets
The film should be thin enough to read through
Fold the ink over itself; do not stir it
Listen to the roller: hissing is right, sticky is too much

Why red is the hardest colour in this room

Red is the colour this room is built around and it is the one I get wrong most. Printing ink is transparent to a degree that surprises everybody at the start, so a red laid over warm cream paper comes up orange, and the same red over a cool white comes up pink. Neither of them is the red on the slab. The only reliable method I have found is to mix on the glass, take a knife-scrape onto the actual paper the job will use, and let it dry, because a red that is convincing while wet dries back by a noticeable step.

Warming or cooling a red is a matter of tiny quantities. A knife-tip of yellow turns a cold red into something that reads as warm from across the room; the same amount of blue takes it towards a colour that looks like dried blood on cream and quite good on grey. White is the one to be careful with, because white makes pink rather than a paler red, and once a mix has white in it there is no route back. When I want a lighter red I add a transparent extender instead and leave the pigment where it was.

Tack, temperature and the lino problem

Tack is the stickiness of the film, and it decides whether the paper comes off the forme cleanly or leaves part of itself behind. A stiff ink on a soft paper lifts fibres, which shows as a furred, slightly bald patch in the middle of a solid. Cold makes every ink stiffer, and a January mix that behaved on Saturday will pluck on Sunday if the heater failed overnight. A few drops of reducing oil loosen a film without changing the colour much, and I keep that bottle beside the slab rather than up on a shelf.

A linocut wants more ink than type does, and for a long time I inked both the same way and wondered why my blocks printed grey. Type is a thin hard face carrying a film to a small area; a lino block is a broad soft surface that absorbs, flexes and gives back less. I ink a block in two directions with a roller charged twice as heavily as I would for a page of text, check the sheen across the surface under a raking light, and accept that a large solid will always have some texture in it. The ones that come out perfectly flat usually look dead anyway.

A swatch book you can print from again

The swatch book is a stack of the papers I actually use, cut to the size of a postcard and held in a clip. Every mix I am pleased with gets a scrape on each of four papers, and on the back I write the date, the room temperature, roughly what went into it in knife-loads, and what it was for. Knife-loads are not a unit anybody else would accept, but they are repeatable within my own hand, and three loads of red to one tip of yellow has brought me back to the same colour more than once.

Scrapes are not prints, which is the limitation to keep in mind. A knife-scrape is thicker than anything a roller will ever lay down, so it always reads darker and glossier than the finished sheet. For colours I expect to use again I print a proper proof as well, a line of text and a small solid, and clip it behind the scrape. Two years of this fits into one clip and has saved whole evenings. Before it existed I once spent an entire Saturday trying to find a green I had mixed in April.

From the make-ready sheet

Scrape every mix onto the papers you actually print on
Write the date, the temperature and the knife-loads
A scrape always reads darker than the printed sheet
Clip a real proof behind the colours you will want again