Tuesday, August 6, 2013

How to Make a Long-lasting Bar of Soap

A common problem that beginner soapmakers have is making soap that lasts a long time and doesn't melt away in the shower. All the effort, work and ingredients put into making a batch of soap, only to have it melt away after just a few washes!

In my experience, formulating your soap to be long-lasting can actually be really easy, when you narrow it down to these three factors:

  • The base oils
  • The water discount
  • The cure time

Base Oils
If you want your soap to be hard and long-lasting, you need to use a balance of hard and soft oils. The best hard oil for long-lasting soap, in my opinion, is palm oil. It's economical, easy to buy, and it contributes hardness, longevity and a smooth creamy lather. Include it in your soap recipe at around 30% of your base oils for a good, hard bar of soap.

TIP: You don't have to buy palm oil from a soap supply store. It can be found in the supermarket in the butter & margarine aisle, called Frymasta in the yellow wrapper. 

Unfortunately there's been alot of controversy around palm oil lately, with many soapmakers (and soap buyers) opting to go completely palm oil free. If you don't feel comfortable using palm oil, try cocoa butter as a substitute. It's more expensive but you won't need to use as much - between 5% and 10% will greatly increase the hardness of your soap. Using more than 10% isn't recommended as it can make the soap dry and crumbly. As an added bonus, cocoa butter also imparts wonderful conditioning properties to the bar!

Water Discount
This is where you reduce the amount of water used in your soap recipe. The resulting bars will become harder much faster during the cure time.

I personally use a discount of 25% water, which equates to 250ml of water to 1kg of oils. I wouldn't recommend going lower than 25% otherwise you may end up with bars being too hard or crumbly. 25% - 35% water is considered the normal range.

TIP: Water discount is not recommended if you're using ingredients that you know may accelerate trace or seize! For example, cinnamon or clove essential oils, milk, honey or beeswax.

Cure Time
Cold process soap is traditionally cured for 4 weeks before use. However, the longer you cure the soap for, the milder and more long-lasting it will be. If you want a really hard bar, try curing for 6 or 8 weeks (or more!) and you will notice a big difference. 

Using The Soap
One more thing that should be noted is that when you're actually using handmade soap, it needs to be kept somewhere that allows it to drain and dry out between uses. Soap that's left sitting in a puddle of water will turn to mush. Make sure your soap dish or shower caddy allows the excess water to drain away and the soap will last much longer!

Questions? Leave a comment below!

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  1. Thank you for this information. This is one of the areas that I struggle with - I feel my soap melts away too quickly. I will try the palm (although I don't really want to use palm in my soap due to the environmental concerns) to see if it makes a difference and also the cocoa butter too. It will be interesting to see the difference & see what is better. I don't mind spending more on the butter because I only make soap as a hobby for my family :-)

  2. Thanks for sharing. I've used palm oil and some beeswax in my latest batch to try to get a harder soap, as my last batch was slimy and didn't last long. Is is worth mentioning that there is sustainable palm oil available? That is what I have used.

    1. I've heard beeswax is good too, although I haven't tried it yet. Yes, of course, and I always use sustainable palm oil! :-)

  3. This is so interesting! Thank you.... It's hard to me to wait 4 weeks before using my soaps so waiting more will be a real challenge lol

  4. Little late to this thread, but Brambleberry seeks sustainable plan oil

  5. thanks for sharing. Hello I'm a soapmaker too from Indonesia.
    in last soap I made, I put until 30% of total weight, papaya juice for extra nourishing ingredients. Is it okay? I have tried that soap. So creamy, smooth, moisturizing but so quickly run out and cannot make a lot of foam lather. I worry if I put too many extra ingredients ...

  6. sorry, may i ask you again?, what soap calculator do you use in soap making?
    thank you :)

    1. I use Oz Calc:

    2. I've tried that calculator. The result has quite different with the lye calc I usually use. I use http://www.soapcalc.net/calc/SoapCalcWP.asp