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Water-based Ink or Water-soluble Ink?
Both Akua Kolor and Akua Intaglio are water-based; only Akua Kolor is water-soluble.
It is important to know the distinction between water-based and water-soluble. The term water-based implies that water is amongst the ingredients. The term water-soluble is used to describe substances that dissolve in water. Akua inks are called water-based because water is used as the solvent to disperse dry pigment into paste form. Akua Kolor is made with gum arabic and is therefore water-soluble. Akua Intaglio is made with soy oil and is not water-soluble. Soap is integral to the clean up of Akua Intaglio ink, as water alone will not dissolve the ink. Non water-solubility is an important quality in an intaglio printmaking ink, as the process requires working with damp paper.
Neal Ambrose-Smith, Coyote Goes Hunting (2007)
Intaglio-Type plate printed by the artist with Akua Intaglio Water-based Ink
Pigment Information
Rostow & Jung select the safest pigments possible. Akua inks do not contain the more hazardous pigments that are known to contain heavy metals such as lead, cadmium, nickel and cobalt. The Akua web site posts a mixing guide for printmakers to learn how to mix color blends and hues for color replacements for the more hazardous pigments.
For example:
Cobalt Blue Hue (replacement for genuine)
Genuine pigment contains Cobalt and Aluminum
Mix:
Ultramarine Blue
Phthalo Blue
Titanium White
Cadmium Red Hue (replacement for genuine)
Genuine pigment contains Cadmium
Mix:
Scarlet Red
Crimson Red
Click for a complete list
relevant links: On Pigments / Safe Painting / Pigment Toxicity

Identifying Pigments
Manufacturers are free to give their art supply colors whatever name they deem appropriate. Different manufacturers give different names to the same color, even if the same pigments are used. Therefore, names may vary from one brand to another. Rostow & Jung try to use the pigment's technical name for Akua Inks. When trying to identify pigments used in ink or paint, research the color index name, not the name given by the manufacturer.
The Color Index Name
The Color Index is a standard list of identification numbers and names given to individual pigments used in all art materials. This information identifies the actual pigment used in a particular ink or paint. It also indicates whether it is made from a single pigment or a mixture of pigments. The color index names for all pigments used in Akua inks can be found on Akua ink labels, website and literature.
Examples:
Ultramarine Blue PB: 29 (single pigment)
PB: 29 - The first letter Identifies whether a pigment or a dye is used. Here the P indicates that a pigment is used.
PB: 29 - The second letter identifies the pigment code. Here, the pigment code stands for blue.
PB: 29 - The number indicates the specific pigment number.
Van Dyke Brown PR101, PR112, PBk7 (mixture of three pigments)
When analyzing Akua's Van Dyke Brown color index name you can see that the color comes from three pigments.

'Quantum Ice', Friedhard Kiekeben,
Intaglio Type Print made using AKUA Intaglio, RIT, 2011

Single Pigment or Pre-mixed Blends
The majority of Akua Inks are made with single pigments. When an artist mixes their own colors, a single-pigment color will mix truer and more predictably. When the manufacture mixes and packages two or more pigments for the user's convenience it is referred to as a pre-mixed blend.
The Akua website has an extensive section devoted to pigment information where you can learn more about pigment types (inorganic and organic) as well as how to mix specific colors.

The Akua Palette / Ink Slab
Akua inks will never harden or skin in the jar or when left out on the plate, ink slab or any non-absorbent surface. Therefore, you never have to clean your palette or worry about damaging brayers, brushes or tools.
The everlasting Akua ink slab can be left uncovered for years.
What is the Difference between Working with Akua Water-based and Oil-based ink?
Working with Akua Intaglio Water-based Ink is very similar to working with oil-based ink. The only change that needs to be made in the studio is the replacement of the solvent can with a bottle of diluted dish soap for clean up. All other methods and materials that the printmaker is used to remain the same. As with all types of printmaking, adjustments can be made along the way to achieve a desired result. Akua modifiers are available to make the ink thicker, thinner or control the transparency.

Testing Inks with a Master Printmaker
In March of 2008, Master Printmaker Tony Kirk and Susan Rostow printed a variety of plates using Graphic Chemical 514 oil-based ink and Akua Intaglio Water-based at the Center for Contemporary Printmaking (CCP) in Norwalk Connecticut.
Master Printmaker Tony Kirk applying ink with card
They found that in almost all situations, prints made with water-based ink were identical to prints made with oil-based ink. Aquatints, line etching, drypoint, and carborundum plates all printed equally well without any modification for either inks.
Donald Sultan (work in progress)
Aquatint printed by Tony Kirk, one printed with Akua Intaglio
and the other with oil-based ink.
The two prints were indistinguishable from one another.
One situation where the Akua Intaglio water-based ink did require modification was while printing a Solarplate by Mary Frank.
Mary Frank (work in progress)
Solarplate printed by Tony Kirk
The Solarplate printed with oil-based ink printed lighter showing the fine, linear marks on the plate.
Mary Frank (detail of work in progress)
Printed with oil-based ink
The print in which Akua Intaglio water-based ink was used appeared very dark with less contrast. This is due to Akua Intaglio's heavy pigment load. In this case, it was necessary to modify the Akua water-based ink in order to reveal the lines and obtain the same results as oil-based inks.
Mary Frank (detail of work in progress)
Printed with Akua Intaglio water-based ink
By mixing 40% Akua Transparent Base into 60% Akua Intaglio Carbon Black water-based ink, the pigment intensity was reduced. Results proved that with this modification, the water-based and oil-based final prints were identical.
Mary Frank (work in progress)
Tony revealing the print

Results from the Perspective of a Master Printmaker
Tony was impressed by the excellent quality of the prints made with Akua Water-based Intaglio inks. He was pleasantly surprised that he did not have to adjust his familiar working methods. Although he used the same techniques, the entire process of wiping the plate and cleaning up Akua ink was done with less effort and time than with oil-based ink. He especially likes the fact that Akua ink doesn't dry on the slab, which eliminated the need to clean up right away.
Click to view a slideshow documenting Tony and Susan's session comparing processes and print results using Akua Water-based ink and oil-based ink.