Red Cabbage Dye

Red cabbage

I chopped up a few red cabbage leaves and boiled them for about an hour in all, to be left with about 30ml of a deep purple liquid. Purpose: to experiment and see if it will indeed turn into a shade of blue when added to my soap mixture.

I’ve read a few websites where people have tried it out and it worked. Like this blog where a mom dyed eggs using red cabbage and they turned out blue; or this other blog where someone made a Rainbow Bento using various vegetable dyes, including red cabbage for a nice shade. The bento does look really pretty:

Rainbow Bento

But by far the most interesting to me was finding this page, where it gave a rough explanation about red cabbage dye being used as a natural pH indicator in labs. Here’s the photo that caught my attention:

Red Cabbage dye under various pH conditions

Is that cool or what? Now, seeing that soap is basic, when I add it to my soap mixture at trace, it could turn blue (pH8), green (pH9) or yellow. Yellow is most likely at this stage since saponification may not be complete. But will its colour change when the pH drops to the 8-10 range after the soap has hardened after 24 hours?

EeeEEE I CANNOT WAIT to try this out and take some photos!

by Michelle Ho

9 thoughts on “Red Cabbage Dye

  1. Nancy says:

    Hi there! You are definitely onto something wtih the pH in red cabbage dye; I believe that it is sensitive to acidity the same as hydrangeas and some other plants. It’s the vinegar with the red cabbage that gets you robin’s egg blue when you dye eggs.

  2. Jaina says:

    The terms of basic and saponification process reminds me of chemistry of soap making. I was working for a palm oil and soap making industry in my previous job.
    Anyway, I like your natural dye used in your soap.

  3. Michelle says:

    Huey: there’s only ONE way to find out! :D If and when you do experiment, let us know the results!

    Nancy: Hi! Thanks for writing up on your easter egg dyeing session, it really helped me with my search on natural dyes for my soap. Your results were so pretty. :) Vinegar in the dye, huh? Well, let’s see how my test batch goes. Can’t add vinegar to my soap mixture though cuz that will impede saponification.

    Jaina: Hey what a coincidence – which department were you attached to at your previous job? Are you quite familiar with soap making then? :) So far the colours that I get for my soap are from clays. They’re natural, yes, but not exactly sustainable… So I’m trying to look for plant-based alternatives wherever I can.

  4. Jaina says:

    Hi Michelle,

    I was working in process engineering dept in oleochemical company. I’m not really familiar with soap making, just know the basic process only as my previous company one of the subsidiary is palm oil and soap making. You worked in palm oil company before? I think soap making process at home is different from the huge manufacturing factory.

    yea, I’m fully support using organic or plant based colours instead of using colourants or harsh chemicals. :)

  5. Priscilla says:

    So read your blurb above about red cabbage as dye and looked around a bit more on the internet and it seemed like a good idea to try. I cooked down on head in two cups of water and concentrated the dye to an awesome purple liquid and added to my CP soap at trace….it turned bright bright yellow just like you thought it would.

    i was disappointed that it was not blue but whatever. So, i uncovered my soap this morning and started cutting,,,,O.M.G. it smells like THE WORST bad cabbage smell i’ve ever smelled!!!!! AWFUL! it WAS lavender soap….now it is cabbage soap.

    I’m Wondering if the smell will fade..also the very outer layer has faded in color to light tan as apposed to a bright mustard yellow.

  6. Michelle says:

    Ching: Always happy to share the little that I know. ;)

    Jaina: Aaah, I see. No I’ve never worked with a palm oil company, only at financial institutions. But I guess you’re right, making soap at home should be vastly different from that at factories, although I’d imagine the basic processes are the same.

    Priscilla: Oh. My. Goodness. :p Sorry, but I couldn’t help but giggle at the thought of soap smelling like rotten cabbage! How much of the dye did you add at trace? Do you have a blog to document this? Looks like the ball’s on your court at the moment, it would be awesome if you could update us on how your soaps look (and smell!) like after another 2 weeks. I really hope the cabbage smell fades! I can’t do any experimenting until I’m out of confinement.

  7. Priscilla says:

    Michelle!!

    O……M…..G…..:)
    The smell was AWFUL! did I say that already?’

    OK, so i let it sit for about a week and the smell started to fade. My husband said it smelled like ass, but what kind of ass he was not sure of…def not cabbage. My eccentric best friend said she liked the smell…who saw that one coming!

    SO i decided that should re-batch the soap and see if i could cook the smell away…as i started to shred it it revealed that putrid mustard yellow inside and an even WORSE smell than before. Needless to say, no matter how awesome the butter content, it’s in the trash.

    Originally what i did was boil and entire head of cabbage in 2 cups of water, when the shreds became a pale blue grey i removed them. I then boiedl the 2 cups of liquid down to about 1/2 ounce of thick, inky dye. I added the entire 1/2 ounce.

    I really don;t think that with another 2 weeks the soap would have lost anymore smell. I even tried cooking down the shredded soap i intended for re-batching and the smell was still there.

    it was a pretty funny experiment!

    I do not have a blog documenting this….and i will not re-enact it! haha!

    Have a great weekend and best wishes!!!

    -Priscilla

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