≡ Menu

making soap

Nine of us made 52 kg of soap today, nine times my recipe at Making Soap in Time for Christmas. It has become an early October ritual – a nice social day at the community centre, making a year’s supply of luxury soap for home and enough to give away as Christmas presents.  We bring a plate and eat lunch together, take it in turns to stir, take home a bucket of soap at trace stage, add our own herbs and essential oils and mould up.  Then there is a flurry of texts and messages – “Mine is ready to mould up”, “Mine too.  Let me know when you cut yours up”, “I just put the sandalwood in and it turned a lovely orange colour”, “How did your lemon myrtle leaves go?”

The soap itself is one thing – a lovely way to neatly sidestep the mad commercialism of Christmas without grinching. But the way that projects like this create community is even more valuable to me.  The Men’s Shed organisation is based around the idea that men talk shoulder to shoulder – solve problems and share insight and support while working together – but maybe that is true of people of both genders.  I know I look forward to soap making every year as much for the day as the soap.



OK, so in The Bathroom Worth the 30 Years’ Wait, I promised the Rocket Stove Bath story. For Siobhanne and others who have asked, here it is.

For many years we had a star bath – a cast iron bathtub out in the open with a wood fire underneath it.  It had its charms, great charms – a clear view of a starry sky, a bath that stayed warm as long as you like, hot water from renewables even in the depths of winter.  But it also had drawbacks – the need to light the fire several hours before bath time, a fair consumption of firewood, no bath in the rain, or even after rain with a fireplace that got very wet, smoky fires, a bath that needed a deal of cleaning at the start of winter.

So the idea was to claim all the charms without the drawbacks, and the rocket stove bath has pretty well aced it.  It is under a roof and has walls most of the way round  but still a view of a starry sky.  Many of my best ideas happen while considering that sky.  It has a chimney that goes all the way along under it, which means the bottom is warm and stays warm for as long as you are willing to add a few sticks every half hour or so.  It is very frugal in its use of wood – a bundle of sticks that I collect from under gum trees along the roadside on my morning walk.  And it burns remarkably clean.

Rocket stoves are a classic design.  The essence of the idea is a vertical combustion chamber that is very well insulated.  Being insulated, it quickly becomes the hottest part of the system, and since heat rises, flame is drawn into it.  Being insulated too, it gets up to very high temperatures and burns all the volatile gases and smoke that cooler fires let escape.  The efficiency makes them ideal for cooking stoves in places where firewood is scarce and for space heating with wood fires in cold climates.

Being a classic design, there’s quite a bit of information around the internet about the basic principles but not much about using them in this application.  So this is my rundown on how we did it, and the things I think might be optional and the things that might be critical.

Step One:  The design

The critical dimensions for a rocket stove are critical.  There is a good explanation  at Design Principles for Wood Burning Cook Stoves that uses research by the lodestars of rocket stoves Dr. Samuel Baldwin and Dr. Larry Winiarski setting out the reasons.

For our purposes:

This is a diagram of the basic design.


  • The diameter of the chamber that the hot gases flow through has to be the same all the way through the system.   Not necessarily the same shape, but the same size.  So the horizontal fire chamber, the vertical rocket chamber, the hot gas drop chamber, the chimney, all have to have the same area for the gases to flow through.  If you “choke” the gas at any point, it doesn’t work.  For example if you use a 6 inch pipe, it has a cross sectional area of 30 sq inches. All exhaust pipes, flues, etc after that can’t be less than 30 sq inches ( or it will throttle the gas trying to escape.)  You can use bigger, or smaller pipe in the burn chamber, and you then need to calculate the cross sectional area and make the flue pipes or exhaust pipe match that size.
  • The length of the vertical rocket chamber (the long vertical bit) has to be greater than 3 times the length of the feed chamber and greater than twice the length of the fire chamber. So a vertical rocket chamber that’s is 900 mm high for example from top to bottom, can have a feed chamber that is less than 300 mm from top to bottom, and a horizontal fire chamber (the horizontal bit) that is less than 450 mm long.

We got a specialist plumbing supplier to make up our rocket, burn and feed chamber out of heavy stainless steel.  It was expensive, but since we were planning to concrete the whole system into place, we didn’t want to risk it ever burning out, and the temperatures get very hot.  We made ours 6 inch (150mm) diameter.  We debated it.  Lewie was barracking for 5 inch (125mm).  I couldn’t conceive of a smaller pipe taking enough wood to heat a bathtub of water, but in retrospect he may have been right. If anyone has tried smaller, let us know!


The plumber did a little design modification on his own, and made the burn chamber go horizontally for 6 inches then at a 45° angle, I think just because it made an easier and stronger weld.  In retrospect, I don’t know that it was a great idea. I would probably insist on it being horizontal if we were doing it again.

Our rocket chamber is 32 inches (81cm) tall.


Over the rocket chamber is a sleeve of galvanised 10 inch (25cm) pipe, and the gap between the sleeve and the rocket chamber is filled with rock wool.  In Version 1, it was filled with perlite.  We lit it up to try it out. It worked beautifully for a couple of baths then stopped working.  Giant frustration.  Took a while then we figured out that the perlite had all settled and compacted and wasn’t up to the job of insulation.  Vacuuming out the perlite to replace it with rock wool was interesting.


After the insulated rocket chamber the gases drop between the galvanised pipe and the bricks, and go out through a galvanised chimney pipe (the curved pipe on the left hand side in this picture).  At the bottom the pipe turns at 90°to the centre of the bath, then turns again and travels under the centre of the bath to come out at the head.  The bit under the bath is rectangular guttering stuck to the bottom of the bath.  Under the bath is filled with perlite and bricked in.  (We had a stack of old bricks put to good use on the project).

At the head of the bath, the chimney turns 90°again and goes up through the rock gabion wall (later filled with rocks).  It has a little cap on top, mostly just to look pretty, and above it the alsynite roof is shielded with a small sheet of metal.  A little smoke comes out when the fire is first lit, but after that not much comes out the chimney, not as heat or smoke.


Version 2, with rock wool insulation, worked beautifully most of the time.  And sometimes just refused.  For no good reason.

We never have totally figured out why. It’s one of those things where you make several changes and can’t tell which one worked, or if they all did.  But three modifications later, the system is working perfectly and perfectly reliably.  Mod 1:  we installed a small fan recycled from a computer in the chimney as a suction.  The idea came from some camping rocket stove designs we found that incorporated a fan. Mod 2:  We built a little semi-circular shovel to be able to remove ash from the burn chamber while the fire was going.  We found that ash in that chamber tended to reduce its area and choke the fire if you have it going for more than one long bath.  Mod 3:  We found a pudding basin that fits very neatly in the open end of the burn chamber – if you look at the first photo in this post you will see it.  We found that letting any air at all in that way made the fire more likely to burn up the sticks rather than horizontally as it is supposed to.

So, the final system.  We can fill the bath with warm water from the solar system, or cold water if it has been really cold and overcast.  With warm water, the bath is ready in half an hour.  With cold a little longer.  It probably doesn’t get hot enough directly under the bath to crack the enamel (as it would with the star bath) but I haven’t wanted to test that.  We fill it first and have a boogie board we put in the bath while it is warming so as to insulate it.

There is a big urn  lives beside the stove with sticks for the fire. We use eucalypt sticks about one to two inch diameter (25 to 50 mm).  Light a small fire in the bottom of the feed chamber, stand four or five sticks in it, and the flame burns horizontally through the burn chamber and roars up the rocket chamber.  The top of the rocket chamber has a big pot with a tap.  This gets very hot and can be added to get the bath to toasty, and refilled from the tap above it.

The hot gases flow along the chimney under the bath keeping it warm.  The sticks drop into the fire as they burn.  If you intend staying in more than half an hour or so, a bath wallah to add more sticks is very helpful. And to bring more wine.


This is a brilliant little video of an experiment done by Harvard Medical School.  It takes under two minutes, and you will never buy any of those household antibacterial wipes or handwash or floor wipes ever again.

The US Food and Drug Administration has recently banned them, both because they just lead to antibiotic resistance, and because several active ingredients are known hormone disrupters.

Bad for you.  Bad for your budget. Bad for people fighting antibiotic resistant infections. Bad for fish and all the other creatures – ones we eat and ones we don’t- trying to maintain some kind of fertility in an increasingly hostile world.  Ordinary soap and water, or for surfaces cleaning vinegar (bottom shelf in the detergent section of the supermarket), with, if you like, lemon skins in it for a dash of nice smelling lemon oil is all you need.  The rest is advertising hype.


So, this one is for you Angus, and for the others who have asked for more detail about building the bathroom “Worth the 30 Years’ Wait”.

bathroom1Like everything permaculture, the first step is to “Observe and Interact“. We didn’t do that.

Our house has a beguiling view to the south, down a valley and off into the distance.  Some mornings, with mist hanging in the valley, it is magnificent. It seduced me into forgetting everything I knew about solar energy and aspect. So we built our main verandah facing south with the kitchen leading onto it, the kitchen roof sloping south, and the wood stove in the kitchen, and … can you see where this is going? In our hemisphere, a solar hot water system has to go on a north facing roof to work effectively.  To be wood stove boosted, the wood stove needs to be pretty directly under it, but our wet-back wood stove was on the other side. The design was all wrong.  You can’t shift the sun.

So we made do with a shower with solar heated water, that wasted too much water waiting for the hot to get through and that often didn’t get properly hot in winter, and a “star bath” – a cast iron bathtub out in the open with a fireplace directly under it. The star bath was glorious.  The fire kept it hot for as long as you like and lying back in a hot bath on a cold winter night watching the stars is one of those major life luxuries.  But lighting the bath was chore too far for midweek workdays and much too far for cold, wet, early dark midwinter midweek workdays.  When I mentioned “stubborn” in the original article, this was the source.  Getting the bathroom right meant going back to fix some fundamental design basics.

It took some years but eventually we reconciled to shifting the kitchen.  The north-east facing verandah doesn’t have the view but it is much nicer to sit on.  The wet-back slow combustion stove now sits directly under the hot water solar panels and tank, and the kitchen sink and the  laundry are a short run.  And it meant we could get hot water to the spot on the north-west side of the house that I had always wanted as the bathroom.

So step one is the one I think we all neglect way way too often, and that is to appreciate the utter intractability of physics. Site a house facing the view – or the street – and you will be stuck forever dealing with too hot, too cold, too dark, too much water wasted, too much power wasted, every element that uses heat or light a struggle. Get the aspect right and everything involving heat and light just flows.

When I say “we” for the rest of this post, I really mean my partner Lewie.  He did all the work on this building project and gets all the credit.

Step two was a bobcat to dig a trench along the uphill (north) side to take the drainage pipe, and also  a length of ag pipe to take storm water runoff away. Drainage pipes for the bath, shower, and basin were laid and the trenches backfilled.

Step three was to concrete in steel corner posts to take the roof and some extra steel posts to help stabilize the gabion walls.

Step four was to build a post and beam roof covered in alsynite.

Step five: install the shower tray and the floor.  The floor is diamond grid – recycled plastic interlocking grid – filled with smooth pebbles.  We’ve since started using diamond grid for paths and drives too – it’s an excellent environmentally friendly material for stopping wet, trafficked areas getting boggy. It has worked brilliantly in the bathroom  No shower mat needed.


Step six was to install the bath and its rocket stove.  The bathroom now has reliable hot hot water year round, from the solar panels in summer and the wet-back slow combustion stove in winter.  The only time this system fails is if it is cold and overcast and we have been away for a few days and the stove hasn’t been lit.  But the star bath spoiled us – I wanted to keep that experience.  I’m going to write a whole nuther post on its own about the rocket stove construction, because we found that there is not a great deal of information on the internet about using rocket stove technology this way, and there was a great deal of learning done along the way. The short story is that it allows us to fill a bath with lukewarm water, light the stove with a small bundle of eucalypt sticks (kept in a big pot next to it for that purpose), and an hour later have a hot bath.  The chimney goes all the way under the bath keeping it warm for as long as you are prepared to add a few sticks every half hour, and we still have the view of the stars albeit not directly above.

rocket stove

Step seven:  The gabion walls for the three outside walls (the forth wall is the door to the house) and the shower cubicle. We used 1.8 metre galvanised grid wire with a 50mm by 75mm grid.  Two parallel runs about 30cm apart, around the outside of the steel posts and back around the inside, tied across every metre or so with heavy galvanised wire to stop it bulging, then filled with river rocks.  We bought the rocks from a landscape supplier (along with the pebbles for the floor) and bucketed them into the gabions – slightly heavy work but the area is not too large and it only took a few hours to do.

The walls are filled to head height around the shower and two walls, but lower in front of the bath to allow a view over the garden and to the stars.  It works for us because we have no neighbours on that side and the bath is designed for use of an evening when no-one is out and about in the garden.


Step nine: plumbing:  We used retro style plumbing fittings, mostly recycled, and got a plumber in to connect the system to the hot water storage tank, which now sits on the roof directly above where I am standing to take this photo.  It means it is a nice short run and I can use the small amount of water it takes before it runs hot to water the plants. The out plumbing goes to another bathtub down the hill a bit, filled with gravel and reeds to filter it, then onto a clump of banana palms.

Step ten: Art deco light fittings found at the dump shop, refitted for 12 volt, and towel hooks on the forth wall.


Step eleven: plants.  I have very tall native ginger and banana palms around the outside on two sides.  The ginger is flowering now, hanging great heavy flower heads into the bathroom.  It is dense enough to be an effective privacy and breeze screen.   There are a couple of big pots with figs, hanging baskets of orchids and ferns hang from the roof around the edge, and I’ve planted around the edge at floor level with lilies, palms, and bromeliads, and crow’s nest and maidenhair ferns around the edge of the shower tray.   A jasmine and a honeysuckle vine both climb the outside of the wire and make their way through the rocks occasionally.


And finally, decoration.  One of the (many) nice things about rock walls is no fire danger, so there are candle holders poked into the rock walls, and I’ve started adding shells and sea glass and crystals and pretty rocks when I find them.  My two-year-old grandson, Teo, helps me find shells, and made a decision on his own to add some treasures to Grandma’s bathroom decorations.



bathroom orchids

I so love having fresh flowers in my bathroom these days. My bathroom “Worth the 30 Years’ Wait” has hanging baskets all around the edge, lilies along the side, and I’ve discovered orchids.   This orchid is right next to the shower-   I can admire it while I soap myself.  It is the forth orchid to flower this year, and so far my favourite with its delicate mauve centres.

I’ve never been huge on growing flowers before.  A nice fertile bit of soil and a choice of what to plant in it and an edible has nearly always won out.  I do like the beauty of many flowering edibles – they feed my native bees, attract predatory insects, and yield seeds for next year’s planting.  Right now I have mustard with bright yellow flowers – great for salads and going to be brown mustard seeds for sprouting and for curries and for pickles.  I have the waxy white flowers of kailan, or swatow broccoli, again wonderful in salads.  I have the purple flowers of endive, going to be seed for next year but mostly just because. I have dill flowering with yellow umbrella heads, good for salads and seed as a spice, and for attracting predatory hoverflies, lacewings, wasps and ladybeetles.  I have Queen Anne’s lace planted for the same purposes.  Soon there will be the lovely little blue flowers of Nigella that I grow for its peppery seeds for pickles and curries.  I would have nasturtiums for salads too but the wallabies found a hole in the fence again and they love nasturtiums even more than I do.

But flowers grown just for themselves are a rare thing for me and I’m discovering a whole new indulgence.

This river lily is growing under the towel hooks. Back when my mother was a girl, orchids and lilies in corsages were a gift for a special date.  It feels very luxuriant to have them all the time.




I cleaned my bathroom for this photo.

I weeded the fig in the pot.  I hung the maroon towels because they look much prettier against the dark aqua wall than the torn barbie doll beach towel.  I threw out the old luffa. Cleaning done.

Oh how I love love love having a bathroom you don’t have to clean.  The moss growing in the corner of the shower is supposed to be there.  The floor never needs mopping.   I put dirt in little crevices in the rock walls to plant ferns and tree orchids.  The late afternoon sun even has an angle that directly hits the towels hanging on the wall so they smell like they’ve just come off the clothes line.

Free hot water, orchids and maidenhair, a fat green frog, a bath that stays warm for hours with a view of the stars, candlelight playing on rocks, and plugholes that take the water out to bananas and mulberries. But really high up on even this list is that I finally, after all these years, have a bathroom that isn’t just not cleaned, it’s not in need of cleaning.


This is one of the two kinds of orchids in flower now, misted with overspray from the shower. I’ve never grown orchids before.

There’s a problem with bathrooms. They are one person rooms, which tends to mean small. They are private, which tends to mean lack of  sun or air. People are naked in them, which tends to mean they are kept warm. They are wet, which tends to mean perfect for things like mould that like a warm, moist, enclosed, unventilated, dark environment.

It’s a basic permaculture notion that you cannot empty an niche.  Where there is a niche, a lifeform will live in it, and aything you do to try to kill that lifeform will harm humans too, and all the other creatures that live in all the places where water goes after it leaves the bathroom. Once upon a time there was a lot of “all the places” and our puny measuring capacity meant we could pretend the killing stuff disappeared.  Nowadays the accumulated total of several generations of bathroom cleaning is showing up in male fertility rates and antibiotic resistant bacteria and fish full of microbeads.

Triclosan, phthalates, butoxythanol, microbeads – there are some really nasty chemicals in bathroom cleaning products.  Homemade lemon oil cleaning vinegar has been my go to alternative, but in a bathroom vs cleaning vinegar match-up, the cleaning vinegar needs to have frequency on its side.  Not fun.

My partner tells me, sometimes with admiration, sometimes with frustration, that I am the stubbornest person.  For all this time I’ve refused to settle on the matter of bathrooms.  But hey, it’s worth it.

Our new bathroom has a hugely efficient, smokeless rocket stove that heats a bathful of water with just a big vase full of eucalypt sticks, picked up anyway to reduce fire hazard.  The chimney leads under the bath to keep it warm for as long as you like. There are little candle crannies in the rocks all around and a view of the stars.

The shower has hot water from the slow combustion stove boosted solar hot water system. The basin is a really old cast iron one with “patina” that matches the old mirror rescued from the dump.  The copper plumbing is all exposed in a kind of steampunk style that bemused the plumber who connected it all. The drain leads out to another bathtub filled with gravel and water plants to filter it, and thence to a clump of bananas.

The room has an alsynite roof that lets light through to give photosynthesising lifeforms an advantage over mould and fungus forms, and means I can fill it with hanging baskets of ferns and orchids and pots of figs and palms.  It has a floor of smooth pebbles in a grid mesh over sand and gravel, which means drips just soak through and I can plant the edges with elephant ears and lillies.  It has rock gabion walls to various heights on three sides – waist height around the bath for a view of a garden in the daytime and the stars at night, but head height round the shower, with a gap to the roof to allow for ventilation and tall, dense native ginger plants around the outside for privacy and breeze protection.  There’s a passionfruit vine too that in time will cover the outside of the gabion wire. The forth side is a full height timber wall to the house with hooks for towels and some lovely old art-deco light fittings we found at the dump years ago, retrofitted to 12 volt.

I shall write another post about the rocket stove construction, because that was a mission of research and trials and invention and building and rebuilding by my partner Lewie worth a post to itself.

Worth the wait.

rocket stove


This year’s soap is in the moulds after a lovely day of soap making with Noelle and Helen and Camilla and Sue and Roz. It should be ready to cut into bars by tomorrow, then it needs to cure for 6 weeks or more to be ready to use.

soap in the moulds

I make soap every year around this time so it is cured in time for Christmas.  It makes a gorgeous present – just enough luxury to be special, just enough everyday usefulness to be used, and no tacky consumerism. And getting it all done this early in a lovely social morning is shopping heaven.

You need a nice open airy place, with a stove or barbeque to melt the oils, and you need to take care – caustic can cause nasty burns if it gets on bare skin.  But with those precautions, it’s not hard. The recipe is in my first soap post here.

First step:  Dissolve the caustic in water, always adding the caustic to the water and not vice versa.  This is the most dangerous bit.  Sue is wearing glasses, and she and Roz are out in the open so as not to breathe fumes.  It instantly gets boiling hot, so we had a test first to make sure the plastic bucket would stand it.

dissolving the caustic

Next step is melting the solid oils and mixing with the liquid oils. By doing it together we can buy the oils in bulk which makes it much cheaper – still not cheap but cheaper.  For $55, I will get about 45 large bars, enough for us for the year and Christmas presents for all those people I want to thank but I don’t want to feel like they have to gift-give in return.

melting the coconut oil

Then we all have a cuppa and wait for the oil and the caustic to both cool down to between 35 and 37 degrees Celsius. We have the big sink at the community centre that you can see at the left, so we put the bucket of caustic in a sink full of cold water to speed it up.

When they are both cool enough, we pour the caustic into the oil in a thin steady stream, stirring all the while.

mix the caustic and the oil

Then it needs to be stirred for about an hour until it is like custard.  This is much more fun taken in turns and accompanied by good conversation!

stir for an hour or so

Then lunch together, giving the mix a stir every so often.  Then we divide it up and take a bucket full of soap at custard stage home to mould up.  It needs to be stirred every so often for another few hours, exactly how long depending on the temperature and humidity.  This lot went off quite quickly, turning into thick, just pourable custard.  At this stage we all mix in our own additives.  I made a third of mine with rolled oats and grated lemon rind, a third with a marshmallow, comfrey, and calendula mix, and a third with luffa embedded in them. I use cut down plastic drink bottles, with the bottoms sealed with packing tape, as moulds.

have lunch

Tomorrow, when it is at a cheese-like texture,  I shall cut out the packing tape and push the cylinder of soap out of the mould and slice into bars with my bread knife.  I’ve learned that if I leave it too long it gets too hard and difficult to slice neatly. Then it will sit in a box in my laundry cupboard till Christmas to cure.


This year’s soap is made and maturing in the cupboard, hopefully safe from the mice who think it is literally good enough to eat. It will go whiter as it matures, and by Christmas it will be hard, white, fine grained soap with a nice clean smell and good bubbles.  So nice to have so much of my Christmas shopping done already!

I make my macadamia, olive and coconut oil soap once a year, in time for it to mature by Christmas.  Usually a few of us get together to make it. It means we can bulk buy the ingredients, and it takes about an hour of stirring to reach trace, and that bit is much more fun taking turns stirring and chatting meanwhile. We each take home a bucket full of soap at custard stage, to thicken a bit more, add final ingredients, and mold up.

The ones that turn out well I give away – they make lovely Christmas presents, and I so love not having to engage with the consumer hype. The ones that don’t cut neatly I keep. I actually still have a dozen bars of last year’s soap left still.  The 4 kg batch of the recipe is usually enough for giving and keeping. The last scraps I put in a pump bottle, cover with water, and use as liquid soap in the bathroom handbasin.

This year I used cut down plastic soft drink bottles as molds – cut the top and bottom off to leave just the cylinder, and used packing tape to tape a circle of plastic cut from a yoghurt container to the bottom.  It sliced into nice sized round bars of soap. It was hot and dry so they set really fast – just one day in the mold and they were ready to slice into bars.

This year I had some luffas to play with, so I made some luffa soap as an experiment, and it turned out wonderfully. I just put luffas in the mold and covered with soap, then sliced right through the luffa into bars.  I wasn’t sure about them so I only made about a third with luffas, so I have a nice batch of luffas to add to the Christmas gift packages as well. The others I made some with my usual lemon rind and rolled oats added just before pouring into the molds, and some with a mixture of herbs given to me by a friend, including mashmallow and calendula.



There are so many great soap makers out there that I hesitated to post this.  Please feel free to leave links and tips in the comments!  But in case you are overwhelmed with too much choice, here’s my one simple, rustic but gorgeous soap making recipe.

I make soap once a year, in time to give it away as Christmas presents. I truly hate the commercialisation of Christmas. Unless I can do handmade presents I feel really yucky and conned by the whole thing.   But homemade vegetable oil soap is so luxurious that it makes a great present.

The downsides are that making luxury soap is not super cheap, and you need to get organised a couple of months in advance to allow it time to cure.  The upside is that it is not that expensive – for about $30 to $40 you can make about 50 bars of soap that is truly decadent.  And having a good incentive to have it done months in advance is kinda nice.

The Recipe:

It is worth being well organised and prepared. It’s not hard at all to make soap, but it is one of those things where there is potential for lots of disasters if you are trying to multitask.

You need:

  • A nice well ventilated space with no kids, dogs or disruptions for a couple of hours.
  • Shoes and long sleeves – caustic soda burns if it splashes on your skin.
  • Plastic gloves.
  • A large stainless steel or enamel pot.
  • A 10 litre plastic bucket.
  • A big plastic or wooden spoon, long enough to stir the bucket.
  • Scales and a measuring jug.
  • Moulds.  Waxed milk cartons work nicely for square soap.  Cut down plastic one-litre milk bottles make round moulds.  Recycled post tubes also make nice round soap if you tape the stopper at the end on well.


  • 1000 gm coconut oil or copha (for good bubbles)
  • 2 litres olive oil (for hardness)
  • 500 ml macadamia oil (for palmitolic acid which is beautiful on your skin)
  • 500 gm solid oil (like Supa-Fry)  (for setting)
  • 687 gm caustic soda

Step 1: Make up your caustic solution

This is the bit that everyone gets worried about.  Caustic burns if it gets on your skin, and when mixed with water it instantly gets very hot and gives off vapour that you’d rather not breathe.  So do this bit carefully in a well ventilated space with gloves and long sleeves.  (And you probably really should wear safety glasses as well).

Use your measuring jug to put 1.83 litres of cold water in the large pot.   Weigh the caustic soda and very carefully sprinkle it into the water, stirring all the while.  The mixture will get very hot and give off vapour. DON’T POUR WATER INTO CAUSTIC (or it might bubble and spit furiously).  Do it the other way round – add the caustic to the water.

Cool this pot of caustic solution to baby’s bath warm temperature.

Step 2:  Mix Your Oils

Pour your liquid oils into the bucket.  Melt the copha and solid oil together,  add to the liquid oils, and mix thoroughly.  Bring the oil mix to baby’s bath warm too.

Step 3: Stir the Caustic Solution into the Oils

When both the caustic solution and the oil mix are baby’s bath warm – between 35° and 37° C – slowly pour the caustic into the oil in a thin continuous stream, stirring all the while.  This mix is still burny so take care not to splash it on yourself.  Continue to stir for about 10 minutes, then frequently for an hour or two, until the mixture has thickened to a thick custard consistency and gone pale.

Step 4:  Add Other Ingredients

At this stage you can stir in other ingredients if you like – essential oils, dried rose petals or lavender, rolled oats.  I like to keep it simple. I added a few handfuls of rolled oats and some grated lemon zest to this batch.

Step 5:  Pour into Moulds

Pour your soap mix into your moulds, banging them to remove bubbles.  Take care – it’s still a bit caustic.  It won’t burn instantly but it will sting.

Step 6: Slice into Bars

Leave it for a day or two to set.  After a day or two, your soap will be set hard enough to slice up.  The longer you leave it the harder it gets, so there is a knack in picking the moment when it is firm enough to cut but not so hard it crumbles. I use a thin bladed bread knife, dipped in boiling water, to slice it up.  This is rustic soap – it won’t slice perfectly neatly and some will crumble. Proper soap makers use individual moulds. You can try “rebatching” the crumbles.

Step 7:  Allow to Cure

The soap needs to cure for several weeks to finish its chemical reaction and harden.  At that stage it will miraculously have lost the caustic sting and will have hardened to a beautiful white, fine grained hard soap with a nice lather and a really luxurious feel on your skin.