cure time and bar size...

[aussie]

... any correlation?

As I understand it (could be wrong!) the saponification reaction is basically complete within a couple of days for cold process, and a lot of what goes on in the rest of the cure time is getting rid of excess moisture. So would thinner/smaller bars (higher surface area/volume ratio) cure faster?

I ask because my mums birthday is exactly 4 weeks from today... I'd love to make her some soap, thinking about trying the pvc pipe thing, I'd be making small rounds 5cm across and 1cm thick. Probably won't get to make them for a couple of days tho so I'll be pushing the cure time.

What do you think?

 

[ericllucas]

Hi: I believe you are thinking right. Saponification takes place largely in the first couple of days and then it is just moisture reduction. If you are looking to have CP soap faster, you can also water-discount and hot-soap. Water discounting is reducing the amount of water you use to mix with the lye. There are numerous posts on this forum about the joys of water discounting. Hot-soaping is simply mixing everything at, say, 140 or 150 degrees, instead of 100 degrees. Hot soaping is okay for rustic soap, but it causes most FO to evaporate quickly.

Please let us know how it goes!

 

[judymoody]

I think that four weeks is probably fine. Most people don't use soap right away. They admire it, and sniff it, and show it off to their friends. I have given soap away that people still have in their homes a year later.

To answer your question, assuming you're not using a finicky fragrance, if you want a faster cure, I agree with taking a water discount. It doesn't speed the saponification time significantly but it will reduce the amount of water to evaporate. However, less water will also accelerate trace somewhat so be prepared for that.

I generally soap at a 33-34% lye solution in soap calc. This works out roughly to a 1:2 ratio of lye to water.

 

[ericllucas]

Hi - I also generally use a 2:1 Water:lye ratio. Soapcalc.net makes it easy to enter this ratio. If I have a lot of olive oil, I occasionally go down to 1.8:1. Here is the thing to keep in mind, however, when water discounting - it is going to go from Trace to Soap-on-a-stick real quick. If you have anything that accelerates trace, like, I don't know, Honeysuckle FO, you'll have soap-on-a-stick immediately. I get the molds ready, mix the lye-water and oils, hit it with the stick blender for a minute, and then before it starts tracing, pour it in the molds. Sometimes by the time I get the soap into the molds, I'm scooping thick mashed potatoes into the mold and pressing it down. Things go quick, so you might want to start with 2.5:1 lye-water or so.

If you hot-soap, you'll get a number of anomalies in your soap - ranging from tiny bubbles in the soap, to a crust on top, to a white film depending on your ingredients (shea butter), to the Dreaded Orange Spots. I only hot soap when I don't care about those things - when I'm making general use rustic soap for my own use. You can make soap really quick, though.

Let us know how it goes!

 

[aussie]

Thanks for the advice, I will give the water discount a go. Especially since I like my olive oil Does lavender oil accelerate trace?
Now to find some pipe...

 

[Relle]

I've never had any probs with lavender accelerating.

 

[Lindy]

I sell my soaps 3 weeks after making them. They are well cured (except Castille - 100% Olive Oil). When I'm making Castille I use high temps to speed trace - I've never had problems with DOS in any other them from high temp soaping.... Most of the time I do room temp because it gives me time to play...