Unlike pigments used for watercolors and oil paints, mineral pigments vary in color and texture according to their particle size.
For example, the smaller the labeling number, the larger the particles and the specific gravity is heavier too. Meanwhile, the larger the labeling number, the smaller the particles and the color appears brighter and whiter because more light reflects on the particles. For example, comparing the same pigment but in No. 5 and No. Byaku (white), you can tell the difference from brightness to saturation is pretty obvious, some may even be surprised and find it hard to believe they are from the same material.
From PIGMENT ARTICLES "Iwa-Enogu, an Essential Coloring Material for Nihonga"
The following is a difference between No. 6 and No.13 of the artificial mineral pigment Gunjo color manufactured by NAKAGAWA GOFUN ENOGU company.
The first comparison is the weight and volume of the mineral pigments.
I filled the same jars with Gunjo No. 6 and No. 13 to the same height and weighed them.
As you can see in the image above, No. 6 is heavier.
In other words, No. 13, which has a lighter specific gravity, comes with a larger volume for the same weight.
At PIGMENT TOKYO, pigments are sold in units of 1 ryo (or 15g), and even for the same quantity, the larger the labeling number of mineral pigment, the larger the volume.
Therefore, when Gunjo No. 6 and No. 13 are mixed with the same volume of binder, No.13 will create more paint than No.6.
The next is a difference in texture.
As mentioned above, the larger the number, the smaller the particles, and thus the opacity also differs. For example, No. 6 reflects light like sparkling sand, while No. 13 has a relatively matte texture like powder.
These are when the pigments are mixed with gum arabic which is the binder used to make transparent watercolors. No.13 has enough opacity to cover the paper palette underneath, while No.6 seems silky and translucent.
Let's try these mineral pigments mixed with the watercolor binder but on paper. They are different when painted next to each other: No. 6 is applied on the top while No. 13 is on the bottom.
【Art Materials Used】
Color Material: NAKAGAWA GOFUN ENOGU Shin-iwaenogu (artificial mineral pigment) Gunjo No. 6 & No. 13
Binder: Gum arabic
Substrate: Bamboo Washi paper for watercolor
Mineral pigments are color materials of which particle size is manufactured for Nihonga (Japanese painting). Therefore, these pigments are usually mixed with animal glue and work best with substrates such as paper and silk. Since the glue has moderate water resistance, you can still dry it evenly after applying a few layers of paint.
On the other hand, gum arabic is not water-resistant, therefore, the watercolor paints will be interfered with if you apply another layer of paint.
For this reason, it is effective and simple to enjoy the texture of mineral pigment by applying a thin layer of paint but when the paint has no covering power, such as No. 6, it will not be firmly fixed to the substrate.
If you're looking to experiment with a different binder other than animal glue for coarser mineral pigments, acrylic emulsion is a highly recommended option.
Acrylic emulsion is a solution made from acrylics, which serves as the binder for acrylic paints. This medium can be mixed with pigment pastes, Mizuneri (Japanese pigment pastes) or conventional pigments to create original acrylic paints.
Because it becomes water-resistant when it dries, colors can be applied in more layers compared to using animal glue as the medium.
Another characteristic of acrylic emulsion is its strong adhesiveness.
For example, when coarse mineral pigments are mixed with gum arabic, the paints can easily peel off like sand paintings when touched. In contrast, using animal glue or acrylic emulsion significantly reduces the likelihood of this peeling issue.
Let's take a look at the difference between No.6 and No.13. The above row shows the result after approximately three coats of paint have been applied. Similar to using gum arabic, a single coat does not produce a vibrant color. By applying three coats while allowing each coat to dry completely, this creates a rough textured vivid blue.
【Art Materials Used】
Color Material: NAKAGAWA GOFUN ENOGU Shin-iwaenogu (artificial mineral pigment) Gunjo No. 6
Binder: Acrylic emulsion
Substrate: Bamboo Washi paper for watercolor
When No. 13 is kneaded and painted with an acrylic emulsion, it looks like this. In comparison to natural mineral pigments, artificial mineral pigments have a more matte texture and greater opacity. Even when kneaded with acrylic emulsions, these pigments showcase their unique characteristics.
Of course, applying three or more coats can help achieve a more matte finish. However, if you want to create a subtle bleeding effect by layering multiple coats, using animal glue instead of water-resistant acrylic emulsion will allow you to achieve the color bleeding, paint puddles and fluid movement unique to the semi-water-resistant paints.
Furthermore, acrylic emulsions can be combined with a thickener to adjust viscosity, making it possible to obtain the preferred hardness of the paints. However, it's important to note that thickeners do not provide any adhesive strength and can slow down the drying speed. Therefore, it is best to add thickeners in small amounts to control viscosity effectively.
Another medium that creates a water-resistant finish is oil mediums for oil paints, but as mentioned above, they require multiple coats if the pigment is too coarse.
Since oil-based mediums take a long time to dry, they are unsuitable for layering mineral pigments. They are not recommended unless you are aiming for a specific artistic effect.
By understanding the relationship between particle size, pigment color and the properties of different mediums, you can expand your expressive possibilities when working with mineral pigments.
Translated by Atsumi Okano, Nelson Hor Ee Herng
PIGMENT TOKYO Art Materials Experts
Art Materials Expert at PIGMENT TOKYO
Akira Oya
Born in 1989 in Tokyo. Master of Fine Art and Design at Nihon University College of Art.
He also continues his career as a visual artist.
Born in 1989 in Tokyo. Master of Fine Art and Design at Nihon University College of Art.
He also continues his career as a visual artist.