The world is full to the brim of beautiful pictures of soap. They are the backbone of soaping sites, Pinterest pages and soaping groups worldwide. Beautiful images of extraordinary masterpieces are a joy, a pleasure and very inspirational, but often it is images of soap that didn’t quite turn out as planned that are the more interesting.
Since I have taken a special interest in heat and gelling related issues of late (you can read about my previous experiments here and here) I tend to home in on images related to that. A couple of months ago I saw a striking image in one of the soaping groups I belong to; a bar of soap with double ’crop circles’. Crop circles is a term of endearment for the visual manifestation of non-uniform gelling in soap. Beginning in the centre of the soap, the heat generated through saponification makes the soap go through gel phase. Depending on size, shape, insulation, ambient temp etc the area gelling in the centre of the soap may or may not spread out to the edges of the soap through the course of saponification. If not, the gelled area vill often look like a dark circle inside a lighter area of un-gelled soap.
In this case the soap had started gelling in the centre but had not gelled all the way to the edges. It had subsequently been placed in an oven with a fairly high ambient temp but only for a relatively short time. The result was an awe-inspiring effect where the heat generated through saponification had created an inner gelled area and ambient heat in the oven had created an outer gelled area. Between the two gelled areas was a lighter ring of ungelled soap. Most striking!
Among the usual comments about possibly rebatching this rare work of art were comments in line with “You couldn’t recreate that effect if you tried”.
But what if you could? From my past heat and water discount experiments I have learnt that the heat generation and gelling pattern of saponifying soap can be manipulated by manipulating the water content. Since it’s well known that gelling affects colours in soap, wouldn’t it be possible to harness contrasting gelling behaviour as an intentional design technique? An intentional crop circle technique.
Time for a new experiment! 🙂
From earlier experience I knew that powdered wheat grass gives very different intensity of colour when gelled as compared to ungelled. Hence I decided to use powdered wheat grass as colourant for my first experiment. Chlorophyll greens are nice and natural but they change from bright green to olive-green or brown over time. It’s inevitable and you need to consider this when planning chlorophyll green designs. A good way of keeping things looking interesting even after colour changes, is ensuring that you have enough contrast in the design.
First, I prepared my mould for a polka dot pour.
Then, I prepared my ingredients. Much like in my second glycerine river experiment I divided my lye amount in two equal parts and made two different lye solutions; one with a 1/1.4 lye/water concentration (for low-water soap) and one with a 1/2.4 lye/water concentration (for high-water soap). Then I prepared my oils and stickblended in the fragrance and the colourant. When everything was carefully blended I divided the oil, colour and fragrance mixture into two equal parts by weighing it. I added each lye solution to its respective oils and stickblended each soap batter to light trace.
At this point the high-water batter was lighter in colour than the low-water batter. It could be that this was simply because the same amount of colourant was dispersed in a larger volume of batter due to the extra water – or perhaps because the higher oil concentration in the low-water emulsion gave that batter a darker appearance. I intended to make ‘negative’ crop circles (light circles in darker soap) and so the low-water soap was poured into the cylinders and the high-water soap was poured around the cylinders.
(I apologize for the poor quality of these iPhone snapshots) The mould went into the oven where it spent a few hours in 60C after which I turned off the oven and left the soap with the ’night light’ on until next morning.
I didn’t watch the soap the whole time, just noticed that after about 1.5h in the oven the colour change had occurred: the low-water soap that started off being considerably darker than the high-water soap, was now lighter.
..and here it looks as if the high-water soap is in full gel while the low-water soap has finished gel. Note the uneven, puffy look of the high-water soap in contrast with the smooth evenness of the low-water soap.
The next morning was cutting time and yes, I had created a pretty perfect set of intentional crop circles, ie a pattern where the colour or shade differential is due to differences in heat generation and gelling pattern, differences which in turn were caused purely by manipulation of the water content. One oil formula, one colourant, one fragrance, one pour, one ambient temp but two different water concentrations. The high-water soap went through typical, extended high-water gel phase which darkened and intensified the colour. The low-water looked like it went through gel. If it did gel – helped along by the 60C ambient temp – it did so in a swifter and different manner than the high-water soap resulting in less intensive colour.
It was the result I expected – I had managed to create intentional ‘crop circles’ and it was nice to see my theory confirmed. What was particularly interesting, though, was to take a close look at the top of the soap.
As in the glycerine river experiment, the high-water part of the top showed signs of expanding and puffing up during gel resulting in the pronounced craters and the knobbly surface. The low-water soap showed no such signs. But most interesting is the slight but definite soda ash pattern on the surface. The ash had developed on the high-water parts but not on the low-water parts and most notably it had developed where high-water areas bordered on low-water areas. Due to the different heat generation patterns of saponifying low-water and high-water soaps, there will have been a sizeable difference in temp on each side of these border lines during saponification. The low-water soap will have reached a higher temp in shorter time after which it may have cooled down enough for the gelling high-water soap to be warmer. I rarely get ash on my soaps, possibly because I mostly do a steep water discount, but when I’ve had ash it has often developed where soap still hot has been exposed to cool air. Here hot soap would have been exposed to relatively cool soap instead.
The horizontally cut bars, seen at a low angle against the light, show the tell-tale indentations of glycerine rivers surrounding each circle of low-water soap.
The lighter ring inside the perimeter of the low-water circles is due to the same phenomenon that causes ’haloes’ in some soaps with embeds. It happens where saponifying, warm soap in the gel phase borders on a cool surface. In the case of my green soap the cylindrical low-water soap is likely to have generated more heat faster than the surrounding, cooler, high-water soap. Where it bordered on the high-water soap a ’halo belt’ developed in the warmer soap. In the picture on the right of a soap with embeds that I made a year ago, the blue soap developed halo belts as it gelled next to the relatively cool, cylindrical embeds.
So, using my oven at 60C it was possible to manipulate the colour development of relatively big portions of soap next to each other just by manipulating the water content. But what about swirls? Could the method of influencing depth and intensity of colour by water content manipulation be used where thin layers of soap lie next to each other? Would relatively thin layers of soap in close proximity even out temperature differentials to the extent that the effect would be lost? And how would this work with a different kind of colourant?
Time for the next experiment.
Since the first experiment involved a plant derived colourant I now decided to use a mineral pigment. Ultramarine blue works well in soap in that it doesn’t mind either high alkalinity or heat. Ultramarine doesn’t morph and doesn’t change over time. If used at low concentration it may appear grey or take on a greenish hue if used with yellow oils. Ultramarine blue is quite a strong colourant and for a medium blue I usually use about half a teaspoon per 1000g of oils. This time I decided to go with a quarter of a teaspoon of ultramarine blue per 1000g of oils.
I prepared my ingredients just like I did in the first experiment. One lye solution at 1/1.4 lye/water concentration and another lye solution at 1/2.4 lye/water concentration. Colourant mixed with a small amount of glycerine and then carefully stickblended into the oils together with the fragrance. Oil mixture divided into two equal parts and lye solutions added each to their own half of the oil mixture and stickblended to emulsion. As with the green soap the high-water soap was again slightly lighter in colour, but this time the difference was minimal.
I then proceeded to pour the two batters in a kind of faux funnel pour, alternating low-water soap and high-water soap. I’ve never done a faux funnel pour before and I now know that I’ll do it at light trace rather than just emulsion next time. I was worried about the soap setting up too soon but it turns out I had plenty of time to keep pouring the batter in small increments. When I had finished pouring, the soap was still very fluid and the top looked very flat. Since I was planning to cut the bars horizontally I didn’t want to do anything about the top and so I just left it as it was.
I put it in my preheated 60C oven and after about 1.5h I turned off the oven when it looked as if the gelling was nicely under way.
I took the iPhone shots above for documentation purposes and I’m posting them here purposely unedited to show the rather interesting colour changes that this one-colourant soap went through.
In the first pic on the left I’ve just finished pouring the soap, it’s still glossy and fluid and you can see a darker ring of low-water soap around an ’island’ of lighter high-water soap.
In the next pic it has spent about 30 min in the oven. The soap is setting up but no sign of gel yet. Note how the low-water ring has now become lighter than the high-water island.
The third pic was taken after about 1.5h in 60C. Don’t know how anybody else would interpret this but to me it looks like the low-water ring is going through gel phase. The little low-water drip on the surface next to the ring looks exactly like vaseline.The high-water island still doesn’t look as if it’s going through gel phase.
The last pic to the right shows what the soap looked like the next morning. The low-water ring now looks white and the high-water island is clearly darker.
Apart from those couple of low water details on the top you couldn’t really see any great contrasts or differences in colour on the surface of the soap. The slightly veined and uneven light blue was very pretty and looked a bit like blue agate but that was it as far a the surface and moulded sides were concerned. “Ag,well” as we say in South Africa, you can’t win them all and at least I knew I had given it my best shot..
But then I cut the soap..
I had expected some kind of difference in shade between the low and high-water soap, something like a two shade gradient perhaps, but I had never imagined anything remotely as dramatic as this! Not only was the contrast in shade between the low and high-water soap strikingly clear, I also had very clear dark contours between all the low and high-water areas. And because the cut went through very thin alternating layers of soap I also got a show of almost every shade between the lightest and the darkest as the translucent, gelled layers veiled and revealed each other. Pretty impressive for one colourant used at the same colourant/oil ratio throughout.
Interestingly, I can’t see any halos in the light low-water areas, although those areas must have been significantly warmer than the surrounding high-water soap during the initial stages of saponification. The explanation might be that the low-water areas are, in fact, completely ’haloed’. In the green soap as well as in the soap with embeds above, the halo belts are about 3-5mm wide. Since the layers in this soap are thin it could be that the halo covers the entire volume in each low-water layer thus adding to the contrast in shade between low and high-water soap.
Glycerine rivers? Plenty. The amount of pigment used was relatively small and although you can’t see any typical crackle, those dark contours between the low and high-water layers are magnificent ‘rivers’. When you look at the freshly cut bars at a low angle against the light you can see them as indented topographical lines.
Whatever the composition of those so-called rivers really is, I have until now assumed that they are more water-heavy than the surrounding soap and that water evaporation causes them to shrink more than the surrounding soap. Looking at this picture now I’m inclined to think that there is more to it than just water evaporation. The fact that the indentation appears as soon as the bars are cut makes me think that it’s a case of uneven thermal expansion. When the soap is gelling and soft, the ’rivers’ expand more than the surrounding soap from the heat generated by saponification and push away the surrounding soap. As the soap cools down and solidifies, a low pressure builds up in the contracting rivers causing internal tension. As you cut through the fresh soap, the tension breaks and the rivers pull in on themselves creating that immediate indentation.
Nice theory. I’ll stick to it until somebody can tell me what those rivers really are and why they behave like they do 🙂
Lessons learnt? These experiments once again suggest that there’s a lot more to water discount than just how long until you can unmould and how long it takes for the soap to cure.
The ash build-up on the green soap was an interesting lesson suggesting that a steep water discount may help prevent ash. While there was no ash visible on the top of the soap in the second experiment, a closer examination of my stickblender attachments some 24h after the soap was made, is interesting:
The attachment on the left was used to blend the low-water soap and the attachment on the right was used to blend the high-water soap. The un-gelled soap residue on the high-water attachment is powdered with a fine coating of ash while the soap on the low-water attachment shows no signs of ash. Again, one oil formula but two different water concentrations. Just a coincidence – both times? Not likely.
I learnt that it’s perfectly possible to use water concentration as a tool for visual design. I now know that you can manipulate colour intensity not only by making sure that the soap goes through gel phase but also by manipulating water content. In the future I’ll think twice before doing a steep water discount when wanting to achieve deep colours through gelling. Likewise I’ll think twice before not doing a water discount if I want to keep colours light. Of course, I only tested two types of pigments here and it may well be that other types of colourants behave differently.
Finally, I’ll introduce you to the fine cast of characters featured in my blue Intentional crop circle soap:
Aliens? That’s what you get for making intentional crop circles.. 🙂