TURNING NATURAL DYE INTO PIGMENT
Dyes vs. Pigments
In case you missed the memo, there’s one main difference between dyes and pigments. Dyes are substances that can be dissolved in water - that’s why to extract color from most plants, you simply cook them. Pigments, on the other hand, can’t be easily dissolved, only dispersed. These are particles that float freely in the liquid ( not unlike fish in the pond) but don’t dissolve within it, keeping their form. The vast majority of plant colors are dyes. There are a few exceptions, though, for example, indigo. Indigo is a pigment and has to undergo a chemical process in order to dissolve and be used to color fibers. (More on indigo in this blog post)
Pigments vs. Dye Extracts
There is one more form in which the dyes can come in — extracts. Extracts are dyes with all water removed. Think of it like that: making a super concentrated dye bath and letting all water evaporate. Therefore, extracts can be dissolved back into the water, too.
Why make pigments, then, if we can have a powdered form with extracts? Dye extracts are super fine powders. Pigments are dyes connected with alum and soda ash, so the size of the pigment particles is considerably bigger. It’s easier to handle them, and it’s easier to filter them (you’d need a super fine filter to make extracts). Pigments don’t dissolve when mixed with a painting medium, rather let the medium hold them. And they are more lightfast, thanks to aluminum, which is a mordant.
Making pigments is really easy, once you know what to expect, so let me show you my process.
Tools you need:
leftover dye bath
potassium aluminum sulfate (PAS or alum)
soda ash (sodium carbonate)
To turn your dye bath into pigment, start with a strained liquid. You don’t want any parts of plants or threads from fabric to be caught up in the pigment. Pour the dye bath through a fine muslin cloth, and then warm up the dye.
Dissolve alum in the leftover dye bath
Weight around 10g of alum for every 1L of the dye bath. If your dyebath is still quite strong, you might need more alum, to bind all the dye particles. Dissolve alum into your warm dye bath. Alum should bind the dye particles quickly and you’ll see small particles floating in the liquid. Dissolved no more, now they are dispersed.
Neutralize the dye bath
Alum makes the liquid acidic, so now it’s time to neutralize it with soda ash, which is alkaline. This ingredient will react with the acidic liquid and produce a considerable amount of foam. Make sure to use a tall container with enough space for the foam to rise. You need around half of the weight of alum, so usually ca. 5g of soda ash for every 1L of the dye bath.
Check the pH-level
Once both ingredients are combined, check the pH level. It should be neutral (pH 7). I went over 7 on my first try, so I had to add some more alum to push the pH level down.
Wait for the pigment to settle
I moved some of the liquid to a glass jar to show you what’s happening now. The pigments are slowly falling to the bottom of the container and clear water is staying on top. You can see in my jar that the water still has some dye dissolved in it, hence the pale yellow color. I could add some more alum to bind it, but I think I’ll have enough pigment to play with anyway, so I left it the way it is.
Remove the water
Once the pigments settle to the bottom, I use a rubber pear to remove the water from the top. You can also carefully pour it out, making sure that you don’t disturb the sediment.
Filter the pigment
Time to filter the pigment. I don’t have a professional setup, so I am using coffee filters attached to a glass jar. I pour some liquid very slowly. I noticed you either need super high-quality filters (which are expensive), or you need to go slow, otherwise, the filters might break. So I go slow, pouring just a few drops until the pigments start settling on the walls of the filer. After a few minutes, it’s safe to pour in bigger portions.
Let the pigment dry
From 2 L of leftover dyebath, I usually produce 4 filers worth of sediment. Wait for the water to filter through. What you should see at the bottom of the jar should be clear water. All pigment should stay on top of the filter. Carefully take out the filters and lay them out to dry. It will take a few days for the remaining water to evaporate.
Grind in a mortar
This is what the chunks of dry pigment look like after grinding. I use a porcelain mortar to grind them into finer form.
Storing a using
I store the pigments in glass jars and turn them into oil or watercolor paints for my art projects.
The lightfastness of these pigments depends on the quality of the dye you used. For example, madder root was traditionally used to make alizarin crimson red paint and still looks wonderful in old masters’ paintings. But a paint made with hollyhock pigments certainly wouldn’t last centuries. That being said, the elusive nature of natural color can be a feature, not a flaw, so don’t let it stop you, and have fun with the colors nature offers us. I’m sure I will!
May you also find small pleasures in making things you don’t yet have a plan for.
Until next time,
If you want to get a clear overview of the world of plant dyes,
I recently published a small ebook about all the dyeing basics.
You can find it here:
And if you are ready to start diving deep with your dyeing practice,
check out my “Mordants for natural dyes” ebook
with useful tips, recipes, and alternatives, available on Etsy.