Photos from left to right:
Dye based ink made from foraged plants
Yellow ochre pigment mulled with gum arabic binder into watercolor paint
Foraged mineral pigment for making watercolors
Handmade dye and pigment based inks in self filled markers (red ochre, oak gall, walnut)
Ink swatches from Falls Creek Red a red ochre pigment ink
Oak gall + Iron ink, dye based ink
Yellow lake pigment made from a chamisa/rabbitbrush dye
Minerals gathered for pigment used to make Evergreen ink, a pigment based ink
Mulling Falls Creek Red ochre watercolor paint for making a pigment based ink
Ink is a colored liquid used to make marks on paper or another surface. Ink can consist of a pigment and a binder or it can be a dye based ink. A dye is a colored liquid made from infusing plants or other biological material into liquid. In a dye the color cannot be separated from the liquid. The colorant is dissolved in the liquid creating an even transparent color.
The first known inks were made in China 4,000 years ago. These inks were likely made with powdered charcoal or soot. This pigment powder needs a binder to hold it onto a surface and tree gums, such as gum arabic, or animal glues can be used for this purpose. Add some water to powdered charcoal and tree gum and you have a pigment based ink. If you were to filter the ink through a fine cloth the charcoal pigment would collect in the filter and the liquid would flow through the filter.
If you filter a dye based ink all of the ink will go through the filter because the colorant is dissolved the liquid. You can add gum arabic to a dye based ink to increase its viscosity- to thicken it- but it is not necessary. The dye molecules will stain the paper without a binder. Dye based ink is similar to tea. The liquid is colored but there are no particles in the liquid. It is homogenous. It will stain paper. For more information about oak gall ink, one example of a dye based ink, go to my pervious blog post here.
Can you combine a pigment colorant and a dye colorant in an ink? Absolutely.
If you are working with an ink or a liquid watercolor there are some observation that will help you determine if it is a pigment or dye based ink. Can you see through the ink? Is the color even throughout the bottle? Is there sediment in the bottom of the ink bottle? Do you need to shake it before you use it? If you need to shake the ink it is a pigment based ink because the pigment settles to the bottom as it sits undisturbed. If the ink is transparent and even throughout the bottle it is likely a dye based ink. Some pigments are so fine and the binders so thick that the pigment may not sink to the bottom easily, as in Chinese calligraphy ink, India ink, and sumi ink. Some of the products labeled as "Liquid Watercolors" are dye based inks.
Other differences between various inks are in the binders. Acrylic inks use acrylic binders. Watercolor inks use watercolor binders, generally gum arabic, a tree resin. These binders hold the pigment dust onto the paper so the pigment powder does not rub off like chalk dust once the ink dries.
At Strata Ink I make pigment based watercolor inks. I make a watercolor paint in the traditional method, by mulling artist grade pigment (much of it hand foraged here in Oregon, but that is a different story) with a homemade gum arabic based watercolor binder on a glass slab. I then add this "fresh" paint to a glass bottle and top it up with distilled water. I think of the resulting ink as a pre-wet watercolor. It can be used straight out of the bottle by using the dropper cap to drip it directly onto your paper. From there one can dilute it with water or mix it with any other waterbased media. Being able to use the dropper to apply your paint makes it easy to create consistent color blends- 3 drops of Maya blue and 3 drops of Chamisa Ochre for instance. You can also drop the paint into already wet areas of you painting so the paint is able to flow as it will. Using this ink is similar to using paint right off of the mulling slab. There are a few videos here where I show you how I use the inks.
With Strata Inks you DO need to shake the bottle before use because the pigment naturally settles to the bottom of the bottle. You will be able to see the layer of pigment if you have let your ink bottle sit for a while. Just shake until the pigment is back in suspension. If you choose to use a palette you can rewet the paint that has dried on your palette just like you would with any watercolor paint.
The world of ink is vast and ancient. The possible formulations are endless. The next time you reach for a bottle of ink I hope you will be able to decipher some of the clues about what is in the bottle.