“I had decided to do what I shall call a Ghost Swirl; a technique where a deliberate design is ’conjured’ into the soap without the use of any added colourant. It’s not essential whether the design is swirled with a skewer or a hanger, poured or spun, in the pot or in the mould. The essential thing is that contrasting shades are achieved purely by manipulation of water content and heat.”
I’ve talked about soap challenges before. I like challenges that inspire me to think a little harder, try new things, and push beyond what I do in my every-day soaping. For me it’s less about competing for sponsored prizes and much more about embarking on a personal creative journey, winning insight and experience.
In a Facebook group I run we regularly run challenges and so I know it’s tricky to set the theme for a good soap challenge. If the theme is too loosely defined and the directions too vague, people don’t know what to do with it. If the focus is too narrow (as in “Make an at-least-five-but-no-more-than-thirteen-colour piped soap emulating your paternal grandmother’s second best quilt”) it easily stifles imagination and creativity. Some kind of middle ground usually works best: define a clear framework, but leave plenty of space for interpretation and innovation within that framework.
This week I’m participating in a plain soap challenge. The instructions are clear; no colourant, no fragrance, just plain soap. Milk soaps are allowed.
That’s my kind of challenge, the kind I like; make whatever you like from simple ingredients and let the soap rather than the additives do the talking.
And I love plain soap. A good, well-made plain soap is sexy. It’s not hiding behind any multicoloured veils, it’s unapologetically naked in all its beauty – and begging to be used, not put on the mantle piece. No soap is better suited for showing off shape, texture and detail from a beautiful mould, and stamps seldom look better than they do on plain soap.
Plain: oval soap on my handwoven linen towel
Plain: Milk & Silk facial soap
Plain: my soap on display at the Louvre in Paris
Plain: Buttermilk Baby soap
Now, this being a challenge I wanted to challenge myself and do something I hadn’t done before. I’ve done a lot when it comes to plain soap, plain soap and I are great buddies and hang out regularly, so this had to be plain soap with a twist.
As I was thinking about what I had done before it occurred to me that a year ago, while I was experimenting with water discount as a design tool (you can read about those experiments here), I had tried titanium dioxide (in the glycerine river experiments that you can read about here and here), mineral pigment and plant pigment. But I had never tried it without any colourant at all. In this present challenge I was allowed milk, but for my purposes milk would just be another colourant and I now had my heart set on trying my water discount technique without any colourant at all.
I had decided to do what I shall call a Ghost Swirl; a technique where a deliberate design is ’conjured’ into the soap without the use of any added colourant. It’s not essential whether the design is swirled with a skewer or a hanger, poured or spun, in the pot or in the mould. The essential thing is that contrasting shades are achieved purely by manipulation of water content and heat.
For this project I wanted to make a design with very fine lines and details to show off the contrasting shades. I chose a modified mantra swirl (which is what I used to call this type of swirls when I first started doing them long before I had ever heard of a Taiwan swirl 🙂 ).
To make a swirl with fine detail I needed a nicely fluid soap batter and so I began my project by choosing an oil formula that would not accelerate trace – even when mixed with a highly concentrated lye solution. I settled for a 1kg batch of avocado oil, castor oil, cocoa butter, coconut oil, olive oil and rice bran oil (in alphabetical order). Once I had decided on the oil formula I calculated the lye and divided it in three equal parts for three lye solutions. Two of the solutions I made to the strength of 44% NaOH and 56% water and one to the strength of 30% NaOH and 70% water. Then, I let all three solutions cool down to room temp.
Big difference in water content there. All three solutions in the picture contain the same amount of NaOH, but you can see from the volume that the solution in the middle has more water than the others. (The droplets on my plastic counter top cover are not lye solution, they are plain water from the outside of the containers that had been standing in cold water to cool down 🙂 )
I melted my hard oils and added my soft oils. I carefully stickblended everything in a big bowl and divided the oil mixture by weight into three equal parts.
While the oils were cooling down to room temp I lined my mould and inserted two dividers.
Once everything was room temp I added the lye solutions to the oils and blended each of the three batters to very light trace. The low water batters were poured in the side compartments of the mould and the high water soap was poured in the centre. I then pulled out the dividers and used a skewer to make a fine swirl. I was way too focused on my pouring and swirling to take any in-between pics, sorry about that 🙂
In this pic the soap is freshly poured. You can see how the high water soap from the centre section is lighter in colour than the low-water soap from the sides. This is typical in raw soap batter. I assume the water droplets suspended in the emulsion reflect more light than the oil does. The more water in the emulsion, the lighter the colour.
Once the soap had set up slightly (the soap was still glossy, but didn’t move when I moved the mould) I transferred the mould to my pre-heated 60C ( 140F) oven.
These are three phone pics ( these are pics for my personal records, please excuse the bad quality) of the soap in the oven. You can follow the gradual change in colour.
Here the soap has just been transferred to the oven; still wet and the high water soap clearly lighter than the low water soap.
Here the soap has been in the oven for 45 minutes. The low water soap is light in colour and the high water soap is darker and moving into gel.
After one hour. The high water soap is now in full gel. Note how the centres of the ’leaf’ shapes in the high water soap are lighter than the surrounding high water areas going through gel phase. Some soda ash has developed – no doubt encouraged by my frequent opening of the oven 🙂
At this point I turned off the heat, left the oven light on and went to bed.
Next morning I unmoulded the soap and cut it – first vertically in blocks and then each block horizontally.
This is what I got:
That’s pretty spectacular considering that there was nothing but masterbatched base oils, NaOH and water in this soap.
So how does this work? Why is the high water soap darker in colour than the low water soap?
Simply put the answer is that the difference in water content influences the pace at which the soap saponifies and how the soap reacts to ambient heat. The difference in reaction to ambient heat results in different gelling behaviour which in turn results in a shade difference in the final soap.
Those who have read Kevin Dunn’s book Scientific Soapmaking carefully, will know that (everything else equal) a low water soap goes through saponification faster and enters full gel phase at a higher temperature than a high water soap does. In this case the 60C temperature kept in my oven was not high enough to force the uncovered low water soap to enter full gel phase. The high water soap, however, did go through full gel at that temperature. But, even though the low water soap did not go through full gel phase it probably was fully saponified before the high water soap was.
So, by manipulating the water content I was able to manipulate the gelling behaviour and by manipulating the gelling behaviour I was able to manipulate the relative depth of colour in the final soap. That’s pretty cool.
I need to point out a couple of things here. The ambient temperature is crucial. 60C seems to be a sweet spot where high water soap gels and low water soap doesn’t. Raising the temperature with say 10C might well change things because when the temp is raised high enough the low water soap will eventually enter full gel too. Whether it will end up looking exactly like the gelled high water soap I don’t know. Exactly at what ambient temp this low water formula (without additives in a batch and mould this size) enters full gel phase I also don’t know because soaping with a big water discount and being more keen on quick saponification than actual gel phase I usually just oven process at 60C. Different oil formulas and various additives like milk (sugar), salt, clay or fragrance may also cause changes in gelling behaviour.
The other thing is the relative difference in strength between the lye solutions. The smaller the difference in water concentration the closer the gelling behaviour of the soaps will be. So, if you want to make sure that the soaps show different gelling behaviour you want your low water soap to be properly low in water. You should, however, never attempt a lye solution stronger than 50%.
What I find particularly fascinating about this Ghost Swirl is that the visual effect is not just two-tone (from gelled and ungelled soap as can be expected); it’s multi-tone. On the one hand you get the difference in shade between the low water and high water soap, gelled and un-gelled soap, but you also get that very interesting dark contour line everywhere were low water soap borders on high water soap.
Exactly why that line looks as dark as it does (it’s well darker than the gelled soap in general) I don’t know. My guess is that the temperature fluctuations on each side of that border line (by the time the high water soap is reaching its heat peak, the low water soap is already well in the process of cooling down) cause continuous pressure and tension changes which result in a crystal structure different from either the main portion of the low water soap or the main portion of the high water soap. Different crystal structures will reflect light differently and therefore look different.
The fact that you can make well-defined designs and swirls inside soap without any colourant is pretty cool, but once again the most interesting thing here may well be the way the top looked when I unmoulded the soap the next morning.
As you can see there’s a good coating of ash on the surface. And not a single speck of that ash is on the low water soap. That’s interesting.
Let’s recap: both the high and the low water soaps have an identical oil formula and superfat, both soaps were poured at light trace and both spent equal time uncovered in the same ambient temp in the oven. The high water soap, now covered in ash, went through full gel phase and the low water soap, now free of ash, didn’t. I don’t think full gel phase as such increases the tendency for ash to develop, but it doesn’t seem to prevent it either. The significant difference here is the water content and the ash development is exactly in line with what I’ve observed before: everything else equal ash seems more likely to happen on high water soap.
Vertically cut blocks waiting to be cut horizontally. Nice wood grain effect! 🙂
shivani
beautiful
Clara
Thank you! 🙂
connie
absolutely genius….two questions: A, where can I join your FB group? B, about the soap…Could you have mixed the two low water/lye solutions into one container, or do you think that would have thrown things off a bit? you are my favorite soaper! when I grow up in my soaping skills, I want to be just like you!
Clara
You could definitely rationalize the method here. You could e.g. make one batter, divide the batter in three and then carefully add more water to one. You need to be careful though when adding plenty of water to a batter you want to keep very fluid; if the water is not the right temp you may easily turn your soap into pudding long before you want to.
jg
Fantastic reading and absolutely beautiful soap. Well done yet again 🙂
Clara
Thanks! 🙂
Claire edmunds
This is a fascinating read. I read your other posts about manipulating water content to achieve different colours, but hadn’t thought of trying with a plain soap. The result you achieved is absolutely stunning! I also love soap challenges as they really push me out of my comfort zone and my competitive nature always means I try my hardest. Which challenge was this for please? I would love to go and have a look.
Clara
Thanks – glad you liked it. This was for a challenge in the Soapmaking With Natural Ingredients Forum -group on Facebook.
Joanne Rochon
Facinating. I love reading about the science of the craft. Beautiful soap. Thank you for sharing.
Clara
Thank you!
dandelion
I love this, your work is such an inspiration!
Clara
Thank you for your kind words!
Debbie
What a great idea, Clara! The soap looks stunning ….. I’m also a sucker for a natural looking soap, so this is my kind of bar. Although I usually do everything in my power to avoid gel, I may just NEED to try CPOP now!!!
Clara
I think it goes to show that there’s a time and place for everything. If you treat gel with respect and are able to control it, it can work in your favour.
saponeta
Increadibly beautiful! I like all your experiments!
I must try this idea, it is fascinating!
Clara
This is really just scraping the surface. I’m sure you could do a lot more with this.
Tina
Absolutely amazing! The idea, the execution, the final result. Perfect, as always 🙂
Clara
Thank you! 🙂
Donna Lee Karlson
Stunning soap (as always)! I can’t thank you enough for your sharing your creativity, experimentation and scientific insights! Your are an phenominal source of inspiration and an exceptional role model!
Clara
Thanks! Glad you enjoyed it! <3
Joy
Love the soap!! Thank you again for this lovely soap experiment, I always look forward and enjoy reading your posts.
Joy
Clara
Thanks! I try to explain things carefully and I’m afraid it often gets longwinded; I’m glad you still enjoy it! 🙂
Rose ericson
Beautiful and WOW. Thanks for sharing.
Clara
Thank you! 🙂
Danee
I DO NOT SOAP and yet I read every single word you post…in fact your blog is one that as soon as I realize you have posted, I head over and start devouring every word. My adoration for your work stems from a variety of factors. The first time I stopped over to visit it was purely because of your gorgeous soaps. Your work is just too beautiful not to inspire my artistic side. But I keep coming back to visit because of your words, your love of experimentation and how you play within your craft. Your need to keep pushing the envelope of soaping and your willingness to ruin a batch or two in the name of learning just does something to my creative side. One of the worst outcomes of this new “Instagram World” that we find ourselves in is the unwritten- but deeply entrenched- rule that we can only show perfection. We aren’t allowed to talk about unhappy moments, real life, or mistakes. Every moment we share is uploaded only after we have tweaked it to perfection and added a filter or two. But real life IS messy and growth IS messy. If we only allow ourselves to work within the boundaries of perfection we can’t grow and learn as individuals or as artists. Sometimes we have to make a batch of soap that looks more like a candy brittle than a beautiful bar of soap in order to advance our skills. You are so willing to make that brittle bar and then keep pushing the envelope further and further until you understand it all and then you take control and bend the soap to do what you want. The Ghost soap is divine and so sublime I can barely stand it. Just pure soaping perfection.
I am fascinated at your attention to detail in every experiment you undertake.
Clara
I’m glad you like it but I so don’t understand it all 🙂 I don’t and that’s what makes it interesting – there are always new things to learn and discover and it’s a fascinating journey. The day I have figured it all out I’ll most probably be done with soapmaking 🙂
Amy Barker
This is absolutely stunning. Thank you for this post.
Clara
Thank you! 🙂
anyaika
Thank you Clara, it’s really amazing. I am also fond of natural soap without any artificial stuff, so I felt the urge to try it when I saw the very first pictures. I’ve read it through several times, but there’s one point I cannot understand. You write, you divided NaOH into three equal parts. If I am not mistaken, it means that the SF ratio must also be equal in each “layer” of the soap. The only thing you altered between them, is the amounts of water. If it is so, what do you mean by the percentages (44%-56% and 30%-70%)? Let’s say, 1000g of oil mixture requires some 380 g of water alltogether. Divided it into three, you get 126.67g. How should I “move” this to get the percentages that you mentioned? Thank you in advance!
Clara
Don’t look at the oils. The percentages describe the concentration of NaOH and water in the lye solution and do not refer to the oils in the formula. Say that my total NaOH for the batch was 300g (which it wouldn’t have been for a 1000g batch of oils, but let’s pretend), then I would have had three portions of 100g NaOH each. In the low water solutions that 100g would have made up 44% of the total lye solution. In the high water solution the 100g would have made up only 30% of the solution because that solution contained more water. Hope this makes sense.
Cathy Gordon
fyi the formula for calculating the water for the lye is 100-x/x so if it was the 44% low water solution it would be calculated 100-44/44 which equals 56/44 or 1..272727 you would then multiply the amount of lye you are using by this 1..272727. Just so you know it took me 2 hrs to figure this out. LOL but now I am set. I can vary the water to lye ratio to anything. I want now
Clara
There you have it! Essentially the fork for your lye concentration is between 1:1 water to lye and 3:1 water to lye. The bigger you want the difference in gelling behaviour, the closer to the extremes you pick your values.
anyaika
Thank you very much, Clara. Absolutely clear. I overcomplicated it a bit. But this relatively high concentration of lye solution frightened me at first sight.
I guess that doing nothing with the water amounts but putting some sugar or honey in the middle row would do something similar: it would also influence the gelling of the layers, wouldn’t it? I must try… :)))
Thank you once again, Clara.
Clara
It might well, but exactly how much sugar you need to bring up the temp enough is guesswork, you’ll have to experiment and take good notes. Just remember that your low water soap is more resistant to overheating than your high water soap is; forcing gel in a 60C oven on a soap high in water and high in sugar may cause cracking and separation. If you add sugar to low water soap – as you suggest – you stand a better chance of avoiding those issues. I did some experiments with overheating – you can check them out here
Brenda B.
I too love a beautiful bar of plain handcrafted soap! This soap you created is a work of art! So creative, so scientific! Clara you are an amazing soap maker. Thank you for sharing. 🙂
Clara
Thank you! 🙂
Amanda
How clever! What a wonderful technique to try. Thank you for sharing!
Clara
Thanks Amanda! 🙂
Karen
Brilliantly simple. Thanks for sharing your technique and observations.
Clara
Thank you Karen!
sindy
Very Nice!
Clara
Thanks!
Joan
Absolutely interesting reading! What beautiful soap….anything but plain. I have heard Kevin Dunn speak several times before at soap conferences. He would love your theories.
Clara
You’re lucky! I’d love to meet Kevin Dunn in person. One day..
Odette Handley
Truly fascinating reading. Thanks so much for this very interesting insight. The soap looks really beautiful.
Clara
Thank you Odette! <3
Joan
I know you have recently visited the US from your blog,..but if you’d like more information on the annual Soap Conference he usually speaks at, you could contact me privately. The one day might happen.
Clara
We had a fantastic, epic trip to the US! Unfortunately though, that means that the ‘travel to the US’ budget has been spent for the next few years 🙂 But to one day be able to attend your soap conference would be wonderful.
Natalia
Clara, you are such a genius! Thank you for this so detailed tutorial!
Clara
Thank you Natalia! <3
Pam
Fascinating study once again Clara thank you for sharing. You can get a similar effect in color by dividing the lye and oils in thirds and adding different sugars to the combinations. That said your study is much more enlightening and I appreciate it.
Clara
The beauty of this is that you can combine it with all sorts of things. Add dye or pigment to the equation and you can do this with an added rainbow effect if you want to. You can use this as an additional effect, a ‘shadow’ effect as it were if you combine it with a coloured swirl. Etc, etc.
Jeanna
Truly beautiful!
Clara
Thanks!
Beth
Thank you so much for sharing your experiments and your knowledge. I love learning, and trying new techniques. Sometimes, understanding the “why” seems beyond me, but your way of sharing information certainly helps. Now I want to play, too.
Clara
To me, the more you know, the more interesting it gets. Since this is what we do we might as well try and understand as much as possible about it. Happy playing! 🙂
Kerri
Seriously – you are a true artistic genius. Absolutely lovely – thank you for sharing and walking us through your thought process and creative process!
Clara
Thanks! Glad you liked it Kerri!
Jo
Thank you so much for writing this blog. You are so inspiring in your experimentation. One question I have is about cold process. You made this soap with hot process. I love cold process soap and so I am wondering if you know if it would work with cold process as well. Or maybe I just need to experiment!
Clara
Normally I would define hot process as a method where an external heat source is used and the soap is moulded after saponification is done. In cold process the soap saponifies in the mould which technically would make this cold process – even if the moulded soap is the kept in a heated oven. But, that’s semantics. You would like to know if this effect could be achieved without any external heat source? I think it can. If you use a 1kg log mould like I did you are likely to be able to get the high water soap to enter full gel phase without the low water soap entering gel phase provided that you cover and insulate the mould very carefully right after pouring the soap. You want to insulate as soon as possible in order for as much as possible of the heat generated by saponification to build up inside the soap rather than escape. The 60C oven works as a handy alternative to insulation: whether it’s hot summer or cold winter the oven temp is constant and that makes the process more predictable.
Carol
Your soaps are always so stylish and sophisticated, and beautifully photographed. I really appreciate the detail and explanation you give as to your methods and the theory behind it. As a newish soap maker, your blog has inspired me to try out new techniques and I’m always delighted by the results. Looking forward to trying this technique. Thank you for sharing.
Clara
Thank you Carol! Trying new techniques is the way to go; it’s not just fun, it also increases your understanding of the process. I hope your version turns out beautiful!
Angela
Elegant suds! I love how your words show your true passion for soap making and the knowledge you have on soap is refreshing to read!
Clara
Thank you! <3
Scottie
This is such a cool project and I really appreciate the depth of explanation. Keep up the good work!
Clara
Thank you!
jeanne
You are a true Master! I am so inspired by your creations and how you keep challenging yourself to do more! Thank you so much for sharing your great knowledge with us!
Clara
Thank you! 🙂
LaTonia
Clara,
Your soap is absolutely gorgeous. I love it. It looks so classy. Who would have thought to experiment with lye and water solutions in one batch of soap. So inspiring!!!
Clara
Thank you – glad you like it!
Kathy
You have taken the science of soaping and created a beautiful art. I love the white on white effect. As another mentioned, your blog is very well written and so easy to read. I have so much to learn. Thanks for posting!
Clara
Thank you! Glad you find it easy to read. It’s good to know that my writing makes some sense – English is my third language.. 🙂
jayshree rukhana
beautiful design..lovely effect..perfect finishing
Clara
Thank you! 🙂
bbee
Just briliant! I just love your work.
I´m a Hobby soaper and your work inspires me!
I will try the Ghost Swirl as soon i have time left.
Best Wishes
Sabine
Clara
Thanks and happy swirling! 🙂
Irene
I find your experiments fascinating, your soaps lovely, and your creativity quite wonderful! The thing I am most curious about with the concept of different water amounts within the same bar of soap is this – what happens a year or two down the road as the water evaporates out of the soap? Will the different sections of the soap pull away from each other? Or as you use the fully dried soap will the less dense sections go faster leaving blank spaces in your soap? It would be interesting to see if it makes a difference. Thank you for all you share!
Clara
No, the different sections don’t pull away from each other, but the high water portions will shrink more than the low water portions. On the cut surface of the soap you will see this as more of an indentation on the high water portions. In my experience there is not much difference in how the high and low water portions wear in use once the soap has cured for about sex weeks or so. But, in my glycerine river experiments where each bar was half low water soap and half high water soap side by side, the borderline between the two portions wore down considerably faster than any other part. This happened with every bar in both batches.
Madame Propre
hello Clara. Thank you so much for your articles, they are always so instructive and inspiring. After reading your previous posts on water contents, I had tried playing around with various patterns creating from various concentrations. Some 6 months down the road, as the soaps are now very dry, they became a little “bumpy”. The different water contents dried differently and as a result some parts of the soap are thinner than others, while the difference in shade has lessened. Did you experience the same ageing process?
Clara
In my experience the high water portions will lighten as the water evaporates and as I said in a previous reply, the high water portions will shrink more as water evaporates and so the low water portions will seem to protrude. Yet, I have one bar of the green batch in front of me and although the green from the plant pigment is no longer very green, the contrast between the darker high water soap and the lighter low water soap is still quite strong. It will be interesting to see what this Ghost Swirl looks like in a month or so – so far it’s looking very much like it did initially. What I do find very interesting about the texture is the fact that it isn’t just the result of more water evaporating from the high water portions over time; there is a clear texture difference on the cut surface immediately, before any water has had time to evaporate (you can see this on the one picture where the freshly cut bar is photographed against the light). I think the different portions expand differently while hot creating pressure and tension differences that are released as the soap is cut.
saponeta
Dear Clara,
I have done it!!!!!
http://www.saponeta.com/2015/10/ghost-swirl.html
I love it! Thank you for sharing your experiences!
Best wishes
Lidiya
Clara
Your Ghost Swirl soap looks absolutely stunning! Hervorragend! 🙂 Well done!
saponeta
Thanks a lot, dear Clara!