MORDANT MONDAY: Is It The Mordant Or The Cochineal?

We get mordant questions all the time at Botanical Colors so why not create Mordant Monday??? Got mordanting questions? Email [email protected]

YOU ASKED: I am a junior Fashion Design student. I am currently working on a project where I am trying to dye cotton yarn with cochineal. I have followed the cochineal instructions on trying to achieve a bright red color however when I take out the yarn from the dye water it begins to turn black. What should I do in order to keep the bright red color on the yarn?


Can you take a picture of what you are describing and also provide the following information:

1.  Is the yarn scoured and mordanted?  What is the mordant and describe the mordanting steps.

2. Are you using cochineal insects or cochineal extract?  If you are using cochineal extract, which one?

3.  What type of red are you trying to achieve?

4. How long does it take for the black color to show up?  Immediately or after a period of time?

5. Are you using any iron in this process (iron pot, iron mordant)

6.  Is the dye bath red and the yarn red in the dye bath?


I went ahead and looked at the materials on the Botanical Colors website and went ahead and tried the dying process again. I used dried cochineal and used a mortar and pestle.

I used alum powder for the mordant. I believe however that the first time around I didn’t boil the crushed cochineal enough to get a strong color. 

The first time around I dyed some cotton yarn and the red didn’t end up sticking to the fiber and when I took it out of the dye bath it almost looked black. The second time I dyed some wool and cotton yarn and was finally able to get the color that I wanted!

Here is an image of the results from the second dye bath!

I was wondering if there is anything that I can do to make the dye turn into more of a red shade rather than a fuschia?


Thanks for the details. Cotton fibers require a slightly different mordant process than wool, so alum only would not have been as successful on cotton only as on wool fibers.  I’m not sure what the dark shades are on the yarn unless that’s a different fiber or something that’s being overdyed.

If you want a redder color, you really need to add more cochineal dye as the deeper saturation will make the color appear less pink and more red.  As well, a small amount of a yellow dye will move the color to a truer red shade.

Another good red recipe is cochineal and madder.  The yellow based red of madder helps reduce the pinkness of the cochineal dye alone.

Hope this helps!