Photo: Frequently asked questions about soap making

Always add lye to water to be safe. (Credit: Brendon Purdy Photography)

Only heard about soap making from the movie Fight Club? Then my month of blogs will help. If Brad Pitt and Edward Norton can do it, so can you!

Week 1: Lye, saponification and cold-process
Week 2: Supplies and ingredients
Week 3: The method in 12 steps
Week 4: A few recipes
Week 5: FAQs

How did people make soap long ago?

Lye (sodium hydroxide AKA caustic soda) wasn't around "back in the day" but other caustic alkalis were: potash — leached from wood ashes — even ashes from seaweed and other plants. In the 1700s, Nicholas Le Blanc figured out how to turn common salt (sodium chloride) into soda ash!

Why add lye to water and NOT water to lye?

Dry sodium hydroxide is highly reactive. A bead of it can burn through layers of skin (remember Fight Club?). In solution — mixing sodium hydroxide with water — a lot of heat is generated, upwards of 90 C! Adding sodium hydroxide to a large volume of water (i.e., lye to water) evokes a less intense and safer reaction.

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Why 27 C to process?

Processing temperature affects the length of time it takes soap to saponify. Processing soaps made with vegetable oils at higher temperatures makes bars more vulnerable to rancidity. I've never had a problem when I stick close to 27 C. And I've read that a higher temperature, like 38 C, can increase five to eight minutes of processing time to ten to 30 minutes.

How long do I cure bars?

My experience is that four to six weeks of curing bars is perfect. Voyageur Soap says that bars are safe to use right away, but curing evaporates water. The longer bars cure, the harder they become and the longer they last in the shower! (That's why some uncured homemade soaps melt quickly!)

What is soda ash?

When sodium hydroxide is exposed to air, it forms sodium carbonate. That's the white powder on top of curing bars. Soda ash isn't as harsh as sodium hydroxide but it's poor quality and can be drying and irritating. I find it's a problem on bar ends, so I slice it off for other household jobs like laundry!

Enter to win a deluxe soap making kit donated by Voyageur Soap & Candle Company Ltd. ($79.95 value)!

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March 31, 2014

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Aug 12, 2015
9:56 AM

Hello, I’ve read about 3 books on soap making so far and a lot of the you tube videos seem like they are for the more experienced soap makers.

Hypothetically, if someone where to give me a mold and say I want you to make me some soap…how would I find out how many pounds does the soap hold and when making a recipe from scratch do you make percentages for each oil that equal the same amount of the mold OR do you combine all of the oils to equal the amount of the mold? I’ve never been very good at math so all of this is a little confusing.

Apr 12, 2014
1:58 PM

I’ve never made soap, but it’s definitely on my list of things to do in 2014!

Apr 05, 2014
11:27 AM

Made a batch of soap, worked really well.

Apr 05, 2014
10:03 AM

Cure time isn’t just about water, there may be small pockets of residual lye and oil that aren’t wholly saponified yet. This is where you want to learn about and use phenolphthalein to test your soap’s alkalinity. If you screwed up your measurements and your soap is too alkali then you don’t want to use it — or have other people use it. In that case you can likely rebatch your soap however.

Also, glycerin with contribute to the rapid demise of a bar of soap. Which is why it’s important to keep it in a proper soap dish — preferably wood — to allow the soap to fully dry between uses and extend it’s longevity.

And don’t waste soap trimming off the outsides when you can just wash the soda ash off with a little hot water.

Apr 04, 2014
10:18 PM

Yes please!

Apr 04, 2014
4:19 PM

Being clean is cool.

Apr 04, 2014
4:04 PM

Nothing better than knowing what is actually in a product you slather all over your body :)

Apr 02, 2014
6:02 PM

Looking forward to trying this out!

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