Sunday, June 13, 2010

Cold-Pressed Lemon-Scented Soap

I've been planning to try my hand at soap-making for the longest time. Keith even bought me a swanky candy thermometer last Christmas. This weekend, I finally got around to it.

I followed Rhonda's cold-pressed soap-making tutorial over at Down To Earth. She describes the benefits of hand-made soap well.

Often commercial soap is made with tallow (animal fat) and contains synthetic fragrance and dye and retains almost no glycerin. Glycerin is a natural emollient that helps with the lather and moisturises the skin. The makers of commercial soaps extract the glycerin and sell it as a separate product as it's more valuable than the soap. Then they add chemicals to make the soap lather.

Her tutorial is an excellent resource, but it had a few holes that threw me along the way. I thought I'd outline some of my problems and resolutions in case any of you are planning to attempt this project.

I found this tutorial was much more specific and you should definitely read through it first, even if you follow Rhonda's photo-guidelines as you make your soap.

There's a lot of equipment to gather, and the amount of oil you need is surprisingly high- I guessed that a bottle of each would be fine, but I had to do some maths and substitute extra oils for the ones I ran out of, so stock up. Or, you know, um, read the recipe properly.

Choose a mould carefully. Rhonda doesn't go into much detail, except to advise choosing plastic or Pyrex over metals. I used a size-appropriate cake tin, but I really struggled to get my finished soap out. Make sure yours has no ridges. Next round, I think I'll line the mould with baking paper.

Find a cute 3 year-old under-chemist to help you grease your mould.

Working with the caustic soda, or lye, is the hairy part of the process, and also the area where I needed to search past Rhonda's tutorial. She's clear on the safety aspects: wear goggles and gloves, don't breathe the fumes - but hazy on the details of the actual process.

You need to add the caustic soda to water in one container, while separately, your saucepan of oils is heating on the stove. Once the lye meets the water, the chemical reaction immediately begins to heat the solution. You're supposed to get the water/lye mix to 50 degrees before adding it to your oils, which must also be at 50 degrees. Tricky.

Be prepared for how fast the lye mix heats - it's unexpectedly swift and according to later reading, it can get to 200 degrees quickly. It's just scary enough to be exciting. By the end of the saponification (soapmaking) process, the caustic soda is neutralised, so your soap will be totally gentle, you can take your goggles off in the shower and you will have learned a new five-dollar word into the bargain.

OK, now channel your inner Sexy Chemist.

It's supposed to take twenty minutes of stirring to reach 'trace', when the soap is stable enough to pour into your mould. I stirred gently, trying not to splash, while chatting to Keith about issues big and small. Mostly small. But the tutorial is a bit off here too.

At twenty minutes, nothing was happening, so I did a little net- searching. Turns out it can take up to an hour to reach trace while hand-stirring, and you need to get some good elbow grease in there to activate things, so it's much better to use a stick blender. As soon as I got the machinery happening, I reached trace in a couple of minutes.

At this stage I added about twenty drops of pure lemon essential oil.

Then it's just a matter of pouring into a mould and wrapping - according to another source- in lots of towels to keep the soap insulated for as long as possible - overnight is best. Hours later, the package still felt like a hot-water bottle under it's layers. What an amazing process.

This morning, it was cool, and smelled lovely.

I unmoulded it- with difficulty, and cut the soap into bars.

It needs to sit to harden and cure for about six weeks now, turned around once a day, before it's ready to use.
I think this batch of soap will last us a long time, and next time, I'll do a better job. The possibilities for soap-related projects are endless: liquid soap, dishwashing liquid, kids shampoo... All up, a totally satisfying Saturday project.


  1. Wow. That's majorly impressive. Well done!

  2. congrats! soapmaking is enormously satisfying and one of my favorite things to do (besides sleeping, perhaps - but I've been known to get up in the wee hours to check on a batch).

    a few points. the term is actually cold POUR or cold PROCESS. not sure where cold press came from - there is no pressing - but it's a fairly common error.

    and you don't have to let it cure for 6 weeks - 4 is plenty, tho you can try it yourself at any time! the cure period is to help the soap mellow a bit, and harden so it lasts longer in use.

    again - congrats!

  3. Oh, wow. I'm dying to try this, but I can't seem to tap in to my inner Sexy Chemist.

  4. Wow, that's very cool. I'm working up to making my own deodorant, using this recipe:

    I just have to find the shea butter and cocoa butter.

    Soap making isn't something I'd considered but now I'm intrigued.

    P&B [formerly Ping - now with blog!]

  5. Just when I was beginning to despair about how few new words I've learned lately, along comes 'saponification'. You're tops.

    And hot. You're totally hot.


Thanks for talking to me. I don't got cooties. Oh, except for when I got cooties.