I use acrylic not oils but you can make either kind of paint and more with natural pigments. Matte acrylic gel can be mixed with the pigments for acrylic paint.
Pigments are ground into fine powders and mixed with a binder to make paint. Powdered pigments are available if you want to make your own paint.
Artist’s paints are usually named after the pigment (like cadmium yellow) but some retain traditional names (like ultramarine blue).
Blue was once obtained from the leaves of the indigo plant. Cuttlefish (squid) ink supplied sepia. Indian yellow was originally made from the urine of camels force-fed on mango leaves. Eww!
Many minerals are used for pigments: lead, titanium, cobalt, cadmium, etc.. These are highly processed to give the strongest and most consistent colors. Aniline dyes were coal tar derivatives discovered during the industrial revolution and have sparked the industry of color making. Pigments like phthalocynine blue (known as phthalo blue) are test tube colors.
Most modern pigments are made in the laboratory (though some natural materials are still used). Modern ultramarine blue is such a color.
You can add any colored pigment (powder) to a binder to make your own natural paints. The best binder is gum arabic to make watercolours (available from art shops). Add a drop of gum to pigment and mix into a paste. Thin with water to use. The paint can be used right away or left to harden into a cake and re-mixed using a brush dipped in water.
Ideas for paint pigments include: soot; coal dust; black and grey ash from burnt paper; brown ash from burnt coal; charcoal; chalk dust; talcum powder; ground up seashells; baked soil; powdered rust; pulverized brick or plant pots; slate; paprika; turmeric, chilli powder, paprika and ginger; powdered graphite; red and yellow ochre; or invent your own.
I found a recipe and several site online that also sell natural pigments. I am interested in trying a couple and then making my own as well. The idea of driving around looking for different soils intrigues me too!
As soon as I make some I will let you know how it goes!