Clay Soap by Auntie Clara's

African Clay: Local, Natural, and Ancient

posted in: Auntie Clara's Blog, Blog Post | 24

One day we’ll reminisce about the pandemic. We’ll sit together looking out in the distance and somebody will say “Do you still remember 2020 and the Great Lockdown?” And then we’ll talk about what we did and didn’t do and how this time changed our lives – if it did.

Rainbow of shweshwe face masks

Like many others I’ve used the extra home time for learning new skills – and brushing up on some old ones. I’ve made dozens and dozens of Shweshwe face masks and put in more sewing hours than in the last 20 years combined. I’ve learnt Tunisian crochet and I’ve learnt to knit sock heals with German short rows. But a really exciting thing I’ve learnt is medieval-style spinning.

A lot of spinners do medieval-style spinning for re-enactment purposes. I’m not big on dressing up in kirtles and escoffions so I’m fine spinning medieval-style in jeans and trainers.

Medieval-style spinning

I’ve been spinning yarn for the past twelve years or so. I could go on about spinning almost for as long as I can go on about soapmaking. Spinning yarn is a beautifully tactile craft. It combines the use of nicely handmade tools with natural fibre and steady rhythm. I own eight fully operational spinning wheels and in the past few years I’ve made dozens of well-balanced drop spindles. But up until recently it never occurred to me to try spinning on a pre-historic or medieval-style spindle. A stick tapered at both ends with a detachable tiny whorl at the end.

Luckily there’s YouTube for everything. After having watched a few of Kathelyne Aaradyn’s videos on grasped and short suspension spinning I was ready to start practicing. I needed a distaff, a tapered spindle stick and a small, compact whorl. To get these tools in the middle of lockdown I had to make them myself. Actual medieval and prehistoric spindles usually have whorls made of stone, bone, clay or lead – none of which I had at hand. But I did have some hardware-store dowels for the distaff and spindle stick – and some polymer clay for the whorl.

Finger distaff, hand distaff and spindles
Distaffs for holding fibre and spindles for spinning

I made a couple of distaffs and a few spindles. It all worked beautifully and I learnt to do both grasped spinning and short suspension spinning: both new and exciting skills. I then had my number one computer fundi Alex 3D-print some whorl moulds for me. With the moulds, a packet of air dry clay and some of my soapmaking pigments I made some really nice whorls.

Air dry clay spindle whorls
Spindle whorls from air dry clay

Clay whorls

Then, with all the confidence of somebody who has made something once, I decided I was ready to make some actual, real clay whorls. And not just from any clay but from local clay that I had seen in the neighbouring vineyard where a deep ditch had recently been dug. I’ve never been a potter and had zero knowledge of different kinds of clay beyond what soapmakers regularly add to soap. But I figured I might be able to harvest clay in nature if people have done it all over the world for millennia.

So, off I went and dug out some surprisingly smooth clay where the digger had cut through ‘virgin’ ground. I’ve been walking in that area for years and have always kept my eyes on local plants, insects and other wildlife. But until I spent that half hour selecting clay on the digging site I had never paid much attention to the ground I’ve been walking on.

Treasure in the ground

I’ve always known that our neighbourhood, much like the rest of our town, is built on clay that has formed from weathered rock over millions of years. But taking a closer look at that clay revealed some interesting things. The clay deep down in the ground was remarkably smooth and pliable with minimal content of roots, rocks or gritty sand. This local clay also turned out to be composed of masses of small, irregular ‘balls’ of smooth clay in a fabulous palette of colours ranging from snow-white through saffron yellow and vermilion red to deep aubergine purple.

Kaolinite, ferricrete, and koffieklip

The clay in this area is largely kaolinite which is common worldwide. Lots of iron in the ground will explain the yellows, reds and purples. The white portions, I assume, are kaolin with less iron contamination. It’s also interesting that distinctly different shades of clay lie jumbled next to each other in the ground rather than having somehow been mixed over time. Possibly water percolated through some portions more than others resulting in different concentrations of iron and other minerals. And it’s probably a result of what we know from soapmaking: iron oxide colourant is not a dye and the colour doesn’t migrate from the pigment itself.

Cross section of clay layers
Cross section of kaolinite clay layers on a steep local dam wall. Red and yellow hues closer to the surface with chunks of white and dark red clay further down.

With my attention now firmly on the ground, I also found that the surface of the ground around here is literally littered with pieces of solidified clay in the full range of gorgeous colours. I had always assumed that the colourful rocks were pieces of fired bricks, but now I realized they are in fact naturally shaped, unfired clay in various stages of lithification. Geologically these pebbles and rocks are called ferricrete: hardened soil cemented together by iron oxides precipitated from the groundwater. The local name for ferricrete is ‘koffieklip’ meaning ‘coffee rock’, no doubt because of the dark brown coffee bean-like inclusions often embedded in the rock.

Koffieklip
Blocks of hard ‘koffieklip’ ferricrete in the foreground
Koffieklip
Koffieklip gravel on the road with everything from soft, porous lumps of dry clay in various shades of yellow and red to very hard, dark ferricrete ‘coffee bean’ pebbles
Salami clay
Chunk of ‘salami clay’. I really wonder how Nature made that..?
Colourful clay
Very pretty gradient layer clay/ferricrete. Red iron oxide rock is known as hematite and yellow iron oxide rock is known as limonite. Here you get the two in one.
Ferricrete
Deep red (hematite) ferricrete embedded in softer soil
Ferricrete
Hematite ferricrete aka red ochre
Kaolinite
Boulders of mostly white kaolinite

Clay whorls unfired

My little local clay spindle whorls turned out beautifully. Especially so after I gave them a polished look by burnishing the drying surface with a smooth gem stone. They’re so pretty that I’m chicken to have them fired; what if they all crack and shatter? Given that they contain a lot of iron I think they need to be fired at rather low temp. Apparently iron works as a flux agent lowering the temp at which the clay melts and becomes liquid.

Spindle whorls from local clay
Spindle whorls made from local clay. An ancient design made with a very modern 3D-printed mould.
Spindle with clay whorl
Medieval-style spindle with stick that I whittled from a green twig and a whorl made from local clay. Border Leicester-merino blend fibre.

Red and yellow ochre

Ceramics from wild harvested clay is fascinating, but you can use clay for a lot more than just pottery. These pigment-rich clays and their lithified versions are widely known as red and yellow ochre and have been used by artists since time began. In fact the oldest known drawings by humans have been found just 300km from here in the so called Blombos Cave by the southernmost tip of Africa. Red lines drawn with an ochre crayon dating back 73 000 years.

Red ochre has been put to all sorts of practical use too. The red pigment can be used as protection from ultraviolet light. The typical red paint used on wooden buildings in Finland and other Nordic countries was traditionally made from a combination of red ochre, rye flour, and iron sulphate. The red-brown flax sails of the sailing barges on the river Thames in England used to be dressed with a protective dressing made from red ochre, cod oil, urine and sea water. Pretty, I’m sure, but the smell must have been a bit of an acquired taste..

Red ochre is commonly available in most parts of the world. It has been and is still widely used in cosmetics as well as for medical purposes. In ancient Egyptian medical texts red ochre was prescribed for healing eye problems, burns, wounds, herpes, painful toes, animal bites, muscle pain and as cosmetic pigments for cheeks and lips.

In Namibia women of the Himba people still apply otjize, a mixture of butterfat, red ochre and sweet-smelling local myrrh to their hair and body on a daily basis. They do it to look and smell good and to protect their skin from the sun and insect bites.  

Clay for my soap

Soapmakers frequently use coloured clays as colourants giving beautiful natural shades. Unlike most plant based natural colourants clay colours will last forever in soap without fading or morphing into something else. Sometimes clay is used to anchor scent in soap, particularly flighty essential oils in coldprocess soap. But there are few reports of tests that would actually prove beyond “I feel” that clay significantly retards the fading of essential oils in soap. 

With my clay whorl project done and dusted I obviously wanted to test my newfound rainbow of clay treasures as soap colourants. How pretty is that line-up of powdered local clay all from an area with a 50m radius!

Powdered clay in many hues
Powdered local kaolinite clays

You can tell that my soap batter got quite thick before I got around to swirling it. But I’m still super excited about this local, natural-colour swirl! In a way it forms the current end on a continuum that started with the red ochre lines drawn in the Blombos cave some 75 000 years ago.. It blows my mind and I love it! 

Clay soap made with local clay
Local clay soap

Minimizing discolouration

The white is uncoloured soap batter for comparison. For scent I chose essential oils that would cause as little discolouration as possible. Mostly lavender with a small amount of neroli and a few drops of patchouli. I like to think that patchouli in soap is like alcoholic beverages in desserts. If you can recognize them clearly you know you’ve overdone it. If you can only pick it up as something distant that you can’t quite put your finger on you got it just right. And, if the clay won’t anchor the scent in the soap a couple of drops of patchouli will last for a decade at least.

For the colours I used a level teaspoon each of powdered clay per 250g of oils. The powdered clay formed a runny slurry with equal volume of water. In that respect it behaves very much like ordinary commercial kaolin clay does and expands much less than bentonite clay does. Some really nice, vivid contrasts there – and as local and natural as can be.

African clay and African clay soap
African clay and clay soap

How safe is it?

An exciting soap colour experiment, but what about safety? You can sanitize wild-crafted clay from organic contamination by boiling it in water or by ‘baking’ dry powder in a very hot oven. I used a metal file to grind very fine powders which I kept in a 250C oven for a couple of hours. Beyond that the caustic soap batter in coldprocess soap is also likely to put an end to any microbes in the clay.

But this natural clay comes with a full spectrum of ‘naturalness’ which may or may not include trace amounts of heavy metals etc. I haven’t had the clay analyzed and I doubt that anybody else has had our local clay analyzed for cosmetic use. The short answer is that I don’t know if the amounts of trace elements in this clay fall within recommended limits. I.e. when adding it to a cosmetic product I’m taking a risk. I’m fine with that in this rinse-off product for my private use. But until I have had the clay analyzed I would not use it in leave-on products and I would not use it commercially.

In soap and other cosmetics you have the option of achieving this type of ‘ochre colours’ with cosmetic grade synthetic iron oxides guaranteed to not contain an excess of heavy metals.

African clay soap
Clay soap and kaolinite clay

So, on a day when enough time has passed and we can look back on the Great Lockdown I’ll be able to say that I did some pretty cool stuff. I made interesting discoveries about the geology in my neighbourhood and learnt new skills. Whether my new discoveries and skills will change my life somehow only time can tell.. 🙂

Spring approaching at the Cape of Good Hope – pandemic or not

24 Responses

  1. Wanda

    Hi Clara

    Thanks so much for the fascinating story of your spinning and the geological info on the clay in your part of the world.

  2. Janet Matherly

    I especially love this posting as I’m a veteran spinner and drop spindle spinner too. I love your creations!♥️ Very interesting regarding the clay and wow the beautiful aray of clay colors. The color vibrancy is amazing. I so hope in the months ahead you will keep us posted on the staying power of the clays in your soap, provided you don’t use them all.

    • Clara

      The colours should stay like this. I used very little water so drying should not have a big effect on the colours. Will be interesting to see though.

  3. Dunia Alpizar Campos

    Wow ! How fascinating stories. Thank you so much for sharing such beautiful pictures. Always a pleasure. Greetings from Costa Rica

  4. martha tavares guedes

    dear Clara, greetings from Brasil… hope you´ve been doing just perfect…

    as usual, you are such a fresh breath of oxygen in everyone´s life…
    all blessings for you and your family…
    stay safe!

    Peace & Love,
    Martha.

  5. Danielle

    Fantastic research for all you posts and such a joy to read! Your posts always lift my spirits and encourage me to try new things in my soap making and my life thank you Clara!

  6. Marcy

    Bravo! I love hearing the back story. I have learned and seen so many new ideas through your blog and photography! And, I follow you on Facebook as well 🙂

  7. Shamila Adam

    Beautiful and truly fascinating article , living in Africa … its home

    • Clara

      There’s something very special about using local ingredients and additives. And the fact that this colourant is the same used by the earliest people makes it extra special.

  8. Sherhonda

    I love your experiments! Thanks so much for sharing the results. Have your soaps cured enough for use? I would be interested in knowing how you liked them once they’re lathered up. They look stunning.

    • Clara

      The soap is not fully cured yet. It will be interesting to see how the clay feels once the soap is cured.

  9. cindy stares

    Fascinating reading. I am a great sofa geologist, and so interested in things like this. I am now going to find some clay for my own soap to try. Thank you for inspiring me . By the way I am in Australia, and that pic of the trees with the paddock looks so much like our bush. Are they Eucalypts ?

    • Clara

      Hi Cindy. They are indeed Eucalypts brought in from Australia. Not sure if they’re blue gums or tuarts though. Both grow around the vineyard.

Leave a Reply

Your email address will not be published.

This site uses Akismet to reduce spam. Learn how your comment data is processed.