MORDANT MONDAY: How Do You Get That Really Red 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’m sending a picture of cotton yarn dyed in cochineal and an exhaust bath of madder. I mordanted this with aluminum triformate but have gotten the same bad results using tannin, then alum with a bit of soda ash. I scoured this yarn very carefully and for at least an hour (boiling). Is there some special trick to dying cotton with cochineal? I get beautiful results with wool.

KATHY ANSWERED: From what I can see in the photo, it appears as if the yarn stuck together, which resulted in uneven dyeing, since the mordant and dye did not penetrate the inside of the skein. This could have been from crowding the dye or mordant pot, or not rotating the yarn enough during the process, or the yarn itself. I’ve experienced the effect you show with silk yarns too, because they cling together and don’t allow for the mordant and dye to enter the skein. I had to fiddle with the strands more than I would with wool to get them to dye evenly. When dyeing with wool, there are still a lot of air pockets in the yarn that allow for liquids to flow through, resulting in more even take up of the dye, even if the skein is large or dense.

YOU ASKED: I’ve read your cochineal insect Instructions and in the Fiber Preparation and Mordanting section I’ve only found information for protein fibers. Is it not possible to achieve a red flag color on cellulose fabrics? 

KATHY ANSWERED: I’ve had the most successful results using the insects with wool and silk to achieve a brilliant red shade. I used aluminum potassium sulfate and cream of tartar. I suspect that the reason this doesn’t work as well on cellulose is that the acidic cream of tartar may inhibit the color on cellulose. I have been able to achieve a really nice true red using two dyes: madder and cochineal with a tannin and alum mordant. I dyed first with madder and achieved a deep reddish orange, then overdyed with cochineal.