What's in an Ink?
World Printmakers has published many in-depth articles on papers, presses and other printmakers' tools and materials, but we've never touched upon the subject of inks. So we asked Michael Craine, managing director of Caligo Inks (who just happen to be one of our sponsors), if he'd answer some questions about the finer points of inks and ink making.
Below --in the longest interview World Printmakers has ever published-- you have his answers. Knowledge is power. Enjoy.
To start out, we'd like to ask you to give a us a brief review of the ink making process ? What's in an ink, where do your raw materials come from?
We manufacture oil-based inks for fine art printmaking and although ink formulation varies according to print method, the essential components remain the same: the colourant and the binder. As ink makers, the colourants we use are pigments and they form the most expensive part of an ink. Colour is a vast subject in its own right and I can only give the briefest of introductions here.
We call the designated area in our factory where we store all our raw materials for ink making our Colour Shop. Here you will find an array of dry pigment colours ranging from the strong, vibrant hues of the modern organics to the muted shades of the natural earths by way of the unique beauty of the inorganics such as ultramarine, manganese violet and iron blue. Fortunately, many of the older toxic inorganic colours can now be replaced with organic alternatives: for example, the diaryl pyrrolopyroles (DPP) are highly resistant replacements for some of the older inorganic colours such as the leads and chromates. For our earth colours - we use synthetic and naturally occurring umbers and siennas (both raw and burnt forms) as well as red and yellow iron oxides. Synthetic earths can be reduced to a finer particle size and these are better suited for use in our lithographic inks.
Black is still the most widely used colour in printing. Carbon Black is produced by the incomplete combustion of natural gas and remains the most common pigment for commercial applications. For the Fine Art printer we add fluffy Lamp Black, Vine Black (or Francfurt) and dense Bone Black to the palette. Bone Black is made from crushed animal bones that are then burned and charred in the absence of air. Like Vine Black, Bone Black has a heavy, granular structure making it particularly suited for use in intaglio inks.
are classified as inorganic and range from opaque to transparent. Of the
opaque whites, Titanium Dioxide deserves special mention as the pigment
with the highest opacity and greatest covering power closely followed
by Zinc Oxide. Two common transparent pigments are Calcium Carbonate and
Aluminium Hydrate, which has the greatest transparency.
In printing inks for fine art applications the most common binder is heat-bodied linseed oil, alternatively known as "burnt copper plate oil", "stand oil" or 'varnish'. Linseed oil is manufactured from the Flax plant and is 'drying oil' which means that it dries by oxidative polymerisation so that a thin wet film of oil will convert, over time, to form a dry film. Linseed Oil has been long used as a binder and medium in printing inks because of its film-forming properties, its pigment-wetting, its dispersing ability and because you can, by the application of heat, thicken and add body and structure to the oil. The longer the heating process, the progressively 'thicker' the oil becomes. Through controlled heating, we can now select from a wide range of oils with differing viscosities grades.
We stock more than 10 different grades of oil binders for use in our inks - our stiffest oil is called 'rat catcher' as it was once used on the old docksides in as an effective if somewhat cruel method of catching the rats and other vermin as they scampered off the cargo ships.
Pigments are delivered to us in barrels, kegs or bags of dry powder and these powders are made up of clusters and clumps of primary pigment particles (aggregates). Unlike dyes, pigments are 'insoluble' in oil and retain their particulate structure throughout the ink making process. A major part our task is to reduce the average size of the pigment clumps (agglomerates) to the approved grind we set for each type of ink and then to distribute them evenly throughout the binding medium. This process is called dispersion. We use a two-stage dispersion process: Pre-mixing followed by Milling.
Pre-mixing takes place in our Colour Shop and here we employ a range of high-speed planetary mixers to agitate and knead the oil-pigment mixture to break up the larger pigment agglomerates and remove any pockets of air. From the colour shop we transfer the pans of dull-looking, partially 'wetted' pigment dispersions to the Milling Shop for further refinement.
Shop houses an array of triple roll mills to complete the dispersion process.
We select the mill according to batch size, which typically varies from
10 to 150 Kg. A roll mill consists of three water-cooled steel rollers
that rotate at increasing speeds. As the ink passes through the pressurised
nips, the pigment clusters are torn apart by a shearing action. In general,
the finer the degree of dispersion, the greater the colour strength and
value, the greater the gloss, the better the abrasion resistance, and
greater the transparency and the better the stability of the finished
What's the difference between a good and a great ink? What are the factors that determine ink quality?
I think it's useful to introduce the idea of "fitness for purpose." Ballet shoes are just the thing if you want to dance but however "well made," they would be quite useless if you wanted to play soccer. And so it is with inks. For example, if you want to make a print from an etched plate then you will get the best results from an ink that was designed specifically for that purpose: it will have certain characteristics that will enable the cylinder of the etching press to push the ink into the incised lines and yet permit itself to be wiped from the surface of the plate without pulling out of the lines. An ink designed for relief printing may be too sticky to wipe from the intaglio plate but perfect for creating a clean crisp image from finely engraved end grain. Conversely, using etching ink as relief ink may reveal transfer problems. And a litho ink may not dry quickly enough for the thicker layers put down in relief printing.
However, there are such things as bad or badly made inks. A bad ink maybe poorly ground and be prone to becoming gritty, it may bleed when you print, fade over time, or may rub excessively. The ink may be inconsistent and change from batch to batch .
A good ink, on the other hand, would be that you can rely on for consistency in shade, body, tack, transparency and strength one from one tin to the next. You should also be able to modify a good ink to suit your own print and plate requirements. A good is also a matter of personal preference and this is particularly true when it comes to an etching ink.
Many characteristics of good and bad inks relate to ink quality and batch consistency. And so ink testing and quality control (QC) form the cornerstones of our work. We keep an approved standard for each ink we make so that we can be sure that our inks remain consistent from batch to batch and from one year to the next. At each stage of manufacture, we carry out a series of quality checks in our ink laboratory to ensure each batch we make meets the approved standard. Our ink lab is well equipped to test for strength, colour, tack, drying time, printability, viscosity, fineness of grind and light fast rating.
The seeds were first sown when Caligo began making inks for artists, well before the deluge of health and safety directives flooded our industry. We made a conscious decision then to select and use pigments and raw materials that presented the lowest impact on the environment, our production staff and our end users.
We are witnessing a similar trend in the art community as printmakers seek out materials and working methods that minimise exposure to toxic substances and reduce any negative impact of printmaking on printmakers and their environment.
When it comes to looking at the Health and Safety issues surrounding printmaking, it is important to note at the outset that the vast majority of 'traditional inks' for artists, such as oil-based etching inks, are non-hazardous in their finished form and when handled appropriately and according to good practice. Unlike commercial inks, the majority of modern oil-based inks for fine art printmaking rarely contain solvents in their formulation, and many ink makers like us, restrict their colour palette to non-toxic pigments and with proper product labelling allow users to make informed choices. The main problem for printmakers comes at wash-up, where oil-based inks have traditionally required solvents at cleanup.
has been to develop water-based binders for inks that obviate this need
for solvents at cleanup and some innovative work has already been done
in the area. Other printmakers are prepared to modify and adjust their
cleanup procedures and wash up with using thin vegetable oils. At Caligo,
we have taken a third approach by seeking to develop a true oil-based
ink that is water washable.
Why did Caligo choose to explore the oil-based approach when water-based alternatives already exist ?
We have built a successful and well respected ink making business by using a range of oil-based binders and so for us, the oil-based approach presented the most natural springboard to further innovation - this is where our expertise lies. Along with our own interest in exploiting oil-based inks, we have had many requests from printmakers for a washable oil-based system for intaglio printing. Oil-based inks have a wonderful history and tradition in fine printmaking and we were keen to explore ways in which our part of the craft could be preserved and at the same time respond to the call to eliminate the need for solvents at clean up.
So are these new Caligo Safe Wash etching inks a breakthrough in water-based ink?
Well actually they're not water-based - our objective was to formulate a binder that would be water-washable and yet allow the ink to retain its inherent 'oilyness' and all the qualities associated with this. The breakthrough is that we have created oil-based etching inks that are water-washable. So, for the first time printmakers can choose to work with an ink that handles and prints as a traditional oil ink, but washes up with just soap and water.
a washable oil-based ink we are extending the options for printmakers
who want to minimise the use of solvents in their workshops. Printmakers
who are familiar with and prefer working with oily inks may also enjoy
working with Caligo Safe Wash etching inks. Our inks retain all the characteristics
traditionally associated with oil-based ink (intensity, clarity, covering
power, handling and wiping characteristics) but without the need to use
solvents or complicated extraction systems at cleanup. So in one sense
it's both about preserving the long tradition of working with oil-based
printing inks and in another sense, provides a genuine breakthrough in
the search for 'greener' ways to run your studio.
We understand the new Safe Wash range of soap washable oil based etching inks is unique in the world today. Is that correct ? Do you think printmakers need environmentally friendly etching inks today?
Yes - I do
believe that it's the first of its kind - a truly oil-based etching ink
that can be washed up with soap and water. As we have said, the majority
of traditional oil based etching inks are non-hazardous when handled appropriately
and sensibly. The area of concern has always been focused upon the use
of solvents at the cleanup stage. It is here that we offer a credible
alternative with our inks.
What are you doing to market these revolutionary inks ? Are they available just in the UK or worldwide?
We are working hard behind the scenes to link up with distributors who are as keen as we are to offer printmakers more choice when it comes to choosing greener alternatives. So if you are a distributor reading this, please contact us!
provides a full list of our current distributors and will be adding to
this in the coming months. Caligo Safe Wash inks are currently
available in the UK, France, Spain, Holland, Germany, Eire, Australia,
Belgium, Denmark, the Netherlands, New Zealand, Norway, Spain, and the
USA. If you are a printmaker and can't get hold of our ink in your area,
please email us firstname.lastname@example.org
and I will keep you posted and direct you to your nearest supplier.
How big are Caligo and how ready are they to take on the world? After recent corporate takeovers you've got some big multinational competition out there.
factory currently occupies some 12,000 square feet of plant and we have
16 employees. We're happy and proud of the fact that we are both large
enough to compete and yet small enough to listen. There are also distinct
advantages to being smaller than the industry giants.
you think you can compete?
The Safe Wash project has certainly been a way for Caligo to be right in the forefront of the exciting non-toxic revolution that's happening in our own industry.
We use the
same pigments as in traditional etching inks and select only those with
a Blue Wool Scale reading of 6 or more. Linseed oil has a proven history
of permanence and durability as a printing ink medium and so we are confident
that the Safe Wash inks have a good pedigree when it come to permanence.
Earlier in our conversation you said that Caligo etching inks have always been non toxic since they are just linseed oil and pigment - they could be spread on toast and eaten for breakfast Surely that's a joke?
Yes, in this litigious age, that's definitely a joke That said, linseed oil finds its place on the shelves of many health food shops and the early ink makers were well known for dipping their bread rolls ('abgeröschte') into the boiling oil as they prepared their varnishes in kettles over fires and made a real feast of it.
For those who like to have further assurance that their materials are safe to use, all the inks in our Safe Wash Etching Range have been tested by toxicologists and conform to ASTM D-4236. In addition they have been approved to carry the ACMI * AP (Approved Product) Seal which identifies art materials 'that are safe and e certified in a toxicological evaluation by a medical expert to contain no materials in sufficient quantities to be toxic or injurious to humans, including children, or to cause acute or chronic health problems'
(* The Art
and Creative Materials Institute)
Caligo Inks can be found at: www.caligoinks.com.
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