My fascination with oval soap began when I was nine and my parents took us on a trip to Zanzibar. From that trip I remember seeing cinnamon trees and smelling fresh lemongrass for the first time and I remember walking through narrow streets in the late afternoon and taking in the amazing fragrance in a little square where fresh cloves had been laid out to dry in the sun.
Yet, for Auntie Clara’s later soapmaking exploits none of that was as significant as the souvenir that my father somewhat hesitantly but kindly bought me. Tucked away in a dark and dusty corner in a bric-a-brac shop in Stone Town I found a treasure: a little ancient-looking oval cardboard soap box large enough to fit one 100g bar of soap. As you lifted the purple, black and silver lid, the oval box was full of shiny golden seed beads and glittering sequins in all the colours of the rainbow. The box still had a vaguely perfumey smell, but mostly it had a reassuringly old smell. Old cardboard, old dust, old drawer and old memories.
To my nine-year-old imagination that box and its contents represented a key to a mysterious, golden, romantic and glamorous past of unknown, but undoubtedly interesting characters. What had the fancy oval soap looked and smelled like, who had used it and for whose beautiful ball-gowns had the beads and sequins been intended? Inspiration for hours and hours of fantasy – and my first crush on fancy soap packaging.
Now the box with beads and sequins are long gone and no matter how I google I can’t find an image of a similar one anywhere. I’m not sure what the fragrance of the soap might have been – judging from the purple on the lid it could have been violet – or lilac. The box must have had some kind of writing on it but that obviously made very little impression on me because I can’t remember it. However, the oval shape of that box with its embossed finish has stayed with me through life and to this day I love an oval bar of soap!
Oval is a great shape for soap. It’s visually appealing and it mimics the shape that soap in use gravitates towards – all sharp corners smoothed out and fitting perfectly in the hand for pleasant grip and easy twirling. There’s something nicely old-fashioned yet eternal about oval soap. It feels great to hold and it’s practical too, since unlike a round bar, an oval bar can be placed on its side without rolling off on unauthorized adventures.
It’s not impossible that my soft spot for ovals in general is inherited. Legend has it that when my father first introduced himself to my mother he offered her some aniseed bonbons. Those same bonbons still come in a pretty little oval tin..
When I started making soap one of the first things I did was look for oval soap moulds. The little oval silicone friand moulds I already had in my kitchen were soon re-purposed as soap moulds and while my better half with his big hands feels that they are the perfect shape and size, I wanted something that would make slightly larger bars.
Being a big DIY enthusiast I was keen to make oval moulds myself – with materials I could source locally. What I could source locally was PVC pipe, and a little googling revealed that round PVC pipe could be heated and re-shaped to make it oval. Sounded simple enough and soon I had my first vertical oval mould. I have since made many more and this is how I do it.
First the pipe. I use heavy duty PVC pipe with a wall of approximately 3.5mm thickness. Outflow pipes are typically made with this kind of pipe since the thick walls make it relatively heat resistant. Heat resistance is a handy feature for a soap mould since soap can get fairly hot.
The caliber of the pipe is obviously a matter of personal preference. I’m always partial to a chunky bar rather than a thin slice so I like to use 75mm pipe and make thicker cuts, but you could use any caliber you like.
How long you want your pipes depends on the size of your oven – and your freezer. Since you are using the oven to heat and reshape the pipe it needs to fit in the oven. Later on, in use, you want to be able to freeze soap in the pipe for easy unmoulding and so the pipe needs to fit in the freezer too. I have a small oven and a narrow freezer so I’ve cut my pipes fairly short.
How you cut the pipe is important too. In use the pipe will be standing on its end, ie you want it cut at a right angle for the pipe to stand straight. The cut itself needs to be as neat and smooth as possible to make the seal at the bottom as tight as possible.
Then the oven. For my heavy duty 75mm pipes I find that 15 min in a preheated 120°C oven is just right. That will soften the PVC just enough to make it pliable with enough resistance not to collapse on itself. Note that heating PVC releases unhealthy fumes so make sure to clear your kitchen of pets, children and pregnant ladies for the duration of this exercise, keep the extractor fan running and open doors and windows for maximum ventilation. Wearing a mask with an appropriate filter is a good idea. Have gloves handy because the pipe will be hot to the touch when you remove it from the oven.
Once the pipe is hot you’ll need to press down on it to flatten it to an oval shape. How much you flatten it will decide what shape the bars will have. It’s very important to press down evenly along the length of the pipe. If you flatten one end more than the other or if you make dents halfway, the soap will never slide out of the pipe.
For pressing down I use a plank that’s longer than the pipe. To make sure that I press down evenly on the pipe – and that I make exactly the same shape each time when I’m flattening more than one pipe – I use guides at each end of the pipe. My guides are simply two equal stacks of kitchen items built up to the intended height of the narrow cross section of my oval.
Before I place the pipe in the pre-heated oven I make sure that my guides are in position and that I have my plank handy. The non-slip mat helps keep the hot pipe in position while I work on it. Once the pipe comes out of the oven you have to work quickly. Since the pipe is now hot and soft you also have to handle it very carefully – you don’t want to dent it accidentally.
You place the hot pipe between the guides and then you immediately press down with the plank until the plank rests on the guides. You keep it down in that position for a minute or two until the pipe has cooled down a bit. I like to do this wearing heavy duty rubber gloves. The gloves offer a fair amount of heat protection while being nicely non-slip.
After you have waited for the pipe to cool down a bit and have removed the plank, the pipe has been flattened and is now only as tall as the guides.
If the re-shaping was successful your previously round cylinder should now be evenly oval.
If you managed to mess it up somehow and you’re unhappy with the shape there’s no need to panic. If you didn’t overheat the pipe and you didn’t push down more than to half the original cross section, the pipe will retract back to its original round shape if you put it back in the hot oven. And once it’s been in the heat for 15 min you can try again.
For standard size round PVC pipes you get end caps that can be used to seal off the bottom of the pipe. For custom shaped oval pipes you don’t get ready made end caps. So, this is how I seal my oval pipes.
One plastic disk (cut from an ice cream container) to fit over the end of the pipe. One corrugated plastic disk to fit inside the pipe. The purpose of the smaller disk of corrugated plastic is to provide a few millimetres of space at the bottom end of the pipe. Once the disk has been removed and it’s time to push out the soap, I can stand the pipe upright and push straight down on the soap (the pipe will be wet with condensation moisture and typically slippery with soap so I prefer not to hold it any more than necessary) with just a bit of space for the soap to move. All I need is to get the soap to move a couple of millimetres and after that it slides out.
The corrugated plastic disk goes inside the pipe and the larger plastic disk is sealed onto the pipe with Presstick aka Blue Tack. If applied carefully the Presstick provides a watertight seal. It’s easy to remove from the pipe, leaves no sticky residue and can be reused.
But, I don’t trust Presstick on its own and so I also fasten a plastic bag with a thick, strong elastic band over the base of the pipe. Twice.
Can’t really be too careful when sealing the base of a PVC pipe. If you’ve ever done the involuntary ’bag-pipe swirl’ (multicoloured soap from your pipe leaks into the bag that you’ve been prudent enough to stand it in) you know this 🙂
Once the soap is in the pipe it’s important that the pipe stands upright until it has cooled down completely. Why? Because heat travels upward and because soap expands as it gets hot and contracts when it cools down. If the opening of the mould is facing straight up the heat has a chance of escaping through the opening and the soap has some space to expand and contract. If the pipe is kept horizontal and the opening faces sideways the heat can’t escape through the opening. The hot, soft, expanding soap will build up pressure against the inside of the pipe and as the hardening soap contracts it will pull away from the wall of the pipe creating a dent in the soap and a vacuum in the space between the soap and the inside wall. This vacuum becomes a very effective airlock that sucks the soap to the inside of the pipe making it a real pain to unmould the soap. Keeping pipes upright and letting them cool down slowly is a good way to minimize this type of airlock.
Here my oval pipe with soap inside has cooled down completely and then spent a good 6h in the freezer. Freezing makes the fresh soap hard and less prone to damage in the unmoulding process. As the pipe warms up, condensation moisture forms between the pipe and the soap and helps the soap slip out of the pipe. (Pleased to see that nothing leaked through my Presstick seal.)
Frozen top of the soap
A few millimetres of space at the base of the mould once the corrugated plastic disk has been removed.
A gentle tap with a rubber mallet on the side of the pipe and the soap slides out. I used to line these moulds until one day I forgot to do it and discovered that unmoulding was easier when the pipe wasn’t lined. I also find that unmoulding from oval pipes tends to be easier than from round cylinders. This might be because a flattened surface ‘gives’ more than a sector of a circle when tapped with a mallet.
When the soap has thawed and the condensation moisture has dried it’s time to cut the soap.
Some oval soaps made in my durable and very inexpensive DIY oval soap moulds. So simple – and very nice!