Ink Formulation

Part of Printing

Printing ink is fundamentally different from writing ink. It must be thick and sticky enough to coat raised type without running into the grooves between letters, transfer cleanly to paper under pressure, and dry permanently without smudging. Formulating good printing ink from scratch is one of the critical skills for establishing a printing operation.

Why Ink Formulation Matters

The best press and finest type in the world produce garbage with bad ink. Ink that is too thin runs off the type and fills in the letter spaces, producing unreadable blobs. Ink that is too thick does not transfer fully, leaving patchy, uneven prints. Ink that never fully dries smudges when pages are stacked. Getting the ink right is as important as every other aspect of printing combined.

How Printing Ink Works

Printing ink has two essential components:

Component	Role	Key Property
Pigment	Provides color (usually black)	Must be extremely fine, opaque, and permanent
Vehicle (binder/carrier)	Carries the pigment, binds it to the paper	Must be viscous enough to stay on type, then dry on paper

Writing ink (iron gall ink, carbon ink dissolved in water) is too thin for printing — it runs, bleeds, and does not transfer from type to paper cleanly. Printing ink uses oil as the vehicle instead of water, creating a thick, sticky paste.

Making Lampblack (Carbon Pigment)

Lampblack — extremely fine carbon soot — is the traditional and best pigment for black printing ink.

Collection Method

1. Build a lamp or candle — Use any oil lamp, tallow candle, or resinous wood splint
2. Position a collector — Hold a smooth, cool surface (a clay plate, a metal sheet, or a large stone) in the flame’s smoke plume, just above where the flame produces visible soot
3. Collect the soot — A thick layer of velvety black powder accumulates on the surface
4. Scrape and store — Scrape the lampblack into a container with a knife or stiff brush
5. Repeat — This is a slow process. Collecting enough lampblack for a day’s printing requires several hours of burning

Fuel Selection

Fuel	Soot Quality	Collection Rate	Notes
Pine resin/pitch	Excellent — very fine, deep black	High	Best overall for lampblack
Linseed oil	Excellent	Moderate	Traditional in European printing
Tallow (rendered fat)	Good	Moderate	Common and available
Beeswax	Very good	Low	Fine particles, expensive
Petroleum/tar	Excellent	High	If available — very dense black
Wood fire	Poor — too coarse	High	Contains ash — not suitable without grinding

Pine Torch Lampblack

The fastest and best method for most rebuilding scenarios: light a pine knot or pitch-soaked wood splint and hold a large clay bowl inverted 5-10 cm above the flame. The bowl fills with fine, pure soot within minutes. Pine resin produces the finest, blackest carbon particles.

Processing Lampblack

Raw lampblack may contain gritty particles. For the finest ink:

1. Mix the lampblack with a small amount of oil
2. Grind on a flat stone with a muller (a smooth, rounded grinding stone)
3. Grind in circular motions for 15-30 minutes until the mixture is perfectly smooth with no detectable grit
4. The longer you grind, the finer the pigment and the better the ink

Making the Vehicle (Linseed Oil Varnish)

The vehicle is what makes printing ink printing ink — not just colored powder. Linseed oil is the ideal vehicle because it dries by oxidation (absorbing oxygen from air), not by evaporation. This gives it time to stay wet on the type but then dry permanently on the paper.

Preparing Linseed Oil

Raw linseed oil (pressed from flax seeds) is too thin for printing ink. It must be heat-treated to thicken it.

Boiled Linseed Oil (Light Varnish)

1. Pour raw linseed oil into a heavy pot — fill only half full (it expands when hot and can boil over)
2. Heat slowly over a moderate fire
3. Bring to a gentle boil — the oil will foam and bubble
4. Maintain the boil for 1-2 hours, stirring occasionally
5. The oil darkens and thickens progressively
6. Remove from heat when the oil has the consistency of thin honey
7. Cool and store in a sealed container

Fire Hazard

Hot linseed oil can spontaneously ignite if it overheats. Never leave it unattended on high heat. If the oil begins smoking heavily, remove from heat immediately. Keep a lid ready to smother any flames — never use water on an oil fire.

Stand Oil (Heavy Varnish)

For thicker varnish — better for fine detail printing:

1. Heat linseed oil in a sealed container (leaving a small vent)
2. Maintain at approximately 280-300C for 6-12 hours
3. The oil polymerizes into a thick, honey-like varnish
4. This produces superior ink with better adhesion and slower drying (useful in warm climates)

Alternative Vehicles

If linseed oil is unavailable:

Oil	Suitability	Drying Speed	Notes
Walnut oil	Good	Moderate	Historically used — lighter color than linseed
Hemp seed oil	Good	Moderate	Similar properties to linseed
Poppy oil	Good	Slow	Used for colored inks
Tung oil	Excellent	Fast	If tung trees are available — best drying oil
Olive oil	Poor	Very slow (non-drying)	Does not polymerize — avoid for printing ink
Animal fat (tallow)	Poor	Does not dry properly	Not suitable as primary vehicle

Only Drying Oils Work

Printing ink vehicles must be “drying oils” — oils that harden through oxidation. Linseed, walnut, tung, and hemp oils are drying oils. Olive oil, coconut oil, and animal fats are non-drying — they stay wet indefinitely and will smear forever. Never use non-drying oils for printing ink.

Mixing the Ink

Basic Formula

Component	Proportion	Notes
Lampblack	15-25% by weight	More = blacker, stiffer
Boiled linseed oil	75-85% by weight	More = thinner, shinier

Mixing Process

1. Place a measure of lampblack on a smooth stone slab (marble, slate, or smooth granite)
2. Add a small amount of boiled linseed oil
3. Grind together using a muller in circular motions
4. Add more oil gradually, grinding continuously
5. Continue grinding for 30-60 minutes until the mixture is perfectly smooth and uniform
6. The ink should be thick like stiff paste — similar to peanut butter or cold honey

The Knife Test

Draw a palette knife or flat stick through the ink on the stone. Good ink should:

• Hold the knife mark (not flow back together immediately — too thin)
• Not crack at the edges of the mark (too thick)
• Show a smooth, glossy surface when smeared thin
• String slightly when you lift the knife (good tack)

Adjusting Consistency

Problem	Ink Behavior	Adjustment
Too thin	Runs off type, fills counters, bleeds on paper	Add more lampblack, grind well
Too thick	Does not transfer fully, patchy printing	Add small amounts of oil, re-grind
Too tacky	Paper sticks to type, tears on pull	Add a drop of raw (unboiled) oil
Not tacky enough	Ink slides off type, prints too light	Use thicker-bodied varnish

Colored Inks

While black is the primary printing ink, colored inks are valuable for decoration, emphasis, and illustrations.

Available Pigments

Color	Pigment Source	Processing
Red	Cinnabar (mercury sulfide), iron oxide (rust), madder root	Grind very fine; iron oxide is safest
Blue	Indigo plant extract, azurite (ground)	Grind; indigo needs mordant
Yellow	Ochre (clay), saffron, turmeric	Grind ochre; plant dyes fade
Green	Malachite (ground), verdigris (copper corrosion)	Grind fine; verdigris is toxic
White	Lead white (toxic), chalk, kaolin	Grind; avoid lead if possible

Toxic Pigments

Cinnabar (mercury), verdigris (copper acetate), and lead white are all toxic. Minimize skin contact, never ingest, and work in ventilated areas. Prefer iron oxide red, indigo blue, and ochre yellow where possible.

Mixing Colored Inks

Same process as black ink — grind the pigment with boiled linseed oil on a stone slab until perfectly smooth. Colored inks typically require a higher pigment concentration because their pigments are less intensely colored than lampblack.

Ink Balls (Application Tools)

Ink is applied to type using ink balls — leather pads stuffed with wool or horsehair.

Making Ink Balls

1. Cut two circles of soft leather (sheepskin or deerskin), 12-15 cm diameter
2. Stuff with clean wool, horsehair, or cotton batting
3. Attach to wooden handles (turned mushroom-shaped)
4. The leather surface should be dome-shaped and smooth

Using Ink Balls

1. Dab a small amount of ink onto one ball
2. Work the two balls against each other in a rocking motion to distribute ink evenly
3. Dab the inked balls over the type form with a light, even touch
4. Re-ink and re-distribute between each inking

Storage and Shelf Life

• Fresh ink is best — mix only what you need for a day’s printing
• Skin formation — A skin forms on stored ink as it oxidizes. Remove the skin before use; the ink underneath is still good.
• Sealed containers — Store ink in closed containers to slow oxidation. Press a layer of waxed paper directly onto the ink surface.
• Cold storage — Ink keeps longer in cool conditions

Common Mistakes

1. Using writing ink for printing — Water-based inks (iron gall, carbon suspension) are completely unsuitable for letterpress printing. They run, bleed, and do not transfer from type. Printing ink must be oil-based.
2. Insufficient grinding — Gritty ink scratches type faces and produces speckled, inconsistent prints. Grind until no grit is detectable between your fingers — then grind more.
3. Wrong oil — Non-drying oils (olive, coconut, animal fat) never harden. Prints remain smearable indefinitely. Use only drying oils (linseed, walnut, tung).
4. Ink too thin — Thin ink fills the counters (enclosed spaces) of letters, turning “o” into a solid dot and “e” into a blob. Printing ink should be thick paste, not liquid.
5. Not testing — Always print a test sheet before a production run. Check ink coverage, density, and drying time. Adjust before committing paper.

Summary

Ink Formulation — At a Glance

• Printing ink = lampblack (15-25%) + boiled linseed oil varnish (75-85%), ground to a smooth paste
• Collect lampblack by holding a cool surface in pine resin smoke; grind with oil on a stone slab
• Boil raw linseed oil for 1-2 hours to thicken it into varnish — never leave unattended (fire risk)
• Only drying oils work (linseed, walnut, tung); non-drying oils (olive, coconut) never harden
• Good ink is thick like peanut butter, holds a knife mark, and strings slightly when lifted
• Apply with leather ink balls worked together to distribute ink evenly
• Water-based writing ink is completely unsuitable for letterpress printing