The hows and whys of changing the lye concentration of your soap

[rparrny]

I read this very interesting article on why the standard value for lye on soapcalc is not the best for most soaps and why it was put there to start with. The table below is a summary...I recommend reading the article. English is obviously not his first language with some of the typos but I really learned a lot about why certain oils will do better with a different percentage of lye.
http://www.japudo.com.br/en/2013/05/14/the-importance-of-lye-concentration/

 

[TeresaT]

All I got out of it was, strong lye solution means quicker trace and hard bar faster. Weaker solution means slower trace and longer time for bar to harden. If you want to do fancy stuff, use a weaker solution and soft oils. If you don't, hard oils and strong solution. I think that's why I soap at 33.333% and room temperature. I randomly selected 33% a few months ago because that seemed to give me the best batter consistency. I soap at room temp because I master batch the lye and my oils. I'm what you might call "lazy" (and proud of it, too! ). As a matter of fact, I think I'm gonna take my lazy self to bed so I can get up early tomorrow and make a few batches of secret feather swirl soaps.

 

[cmzaha]

It is not the percentage of lye, but the concentration of the lye solution. Your lye amount will stay the same only the amount of liquid will vary. I usually use a 33% lye concentration, but do have to vary that for a few recipes, such as fast moving recipes, and cranky fo's and eo's. Pure castile soap I use a 40% concentration. If I soap with tallow and shea I reduce down to a 31% concentration if I want to swirl.

 

[commoncenz]

It is not the percentage of lye, but the concentration of the lye solution. Your lye amount will stay the same only the amount of liquid will vary. I usually use a 33% lye concentration, but do have to vary that for a few recipes, such as fast moving recipes, and cranky fo's and eo's. Pure castile soap I use a 40% concentration. If I soap with tallow and shea I reduce down to a 31% concentration if I want to swirl.

Carolyn, purely out of curiosity, in the bolded part, are you saying if you soap with tallow and shea in the same recipe or if you soap with either tallow or shea? I've yet to soap with tallow, but do use a small percentage of shea in my soaps and they behave fairly well at 33% at room temperature. If I soap hotter, it moves quicker of course.

 

[TeresaT]

It is not the percentage of lye, but the concentration of the lye solution. Your lye amount will stay the same only the amount of liquid will vary. I usually use a 33% lye concentration, but do have to vary that for a few recipes, such as fast moving recipes, and cranky fo's and eo's. Pure castile soap I use a 40% concentration. If I soap with tallow and shea I reduce down to a 31% concentration if I want to swirl.

Am I missing something? Aren't percentages and concentrations the same, though? 40% solution will have 40 units of lye and 60 units of liquid. 25% solution will have 25 units of lye and 75 units of liquid. If I spill one of these on my hand, I want it to be the 25% not the 40% so I'll have a better chance of washing it off before it burns. The 40% is going to be stronger because it has more lye than liquid; so it will trace faster and harden faster because there is less water to slow down the saponification process and less water to evaporate out of the finished process. However, after 6 to 8 weeks, it is a moot point which solution you've used because time is the ultimate dehydrator. I think I've confused myself.

 

[DeeAnna]

Carolyn is talking about a common misconception that many beginning soapers have -- that if I change the lye solution concentration, then I am changing the amount of NaOH. What they're not realizing is that you can use more or use less water to make that solution, while leaving the amount of lye exactly the same.

You are right in that concentration and percentage basically mean the same thing when talking about the lye solution concentration.

"... If I spill one of these on my hand, I want it to be the 25% not the 40% so I'll have a better chance of washing it off before it burns...."

Actually both will burn you equally as fast. Soapers deal with incredibly concentrated lye solutions compared with any other household or hobby use -- as high as would be used only in the chemical processing industry. Whether the lye is at 10% concentration or 50% concentration, the damage will be done in seconds. Only if the NaOH solution is very weak -- well under 10% concentration -- would you see a reasonable slowdown in the rate of damage.

 

[commoncenz]

Carolyn is talking about a common misconception that many beginning soapers have -- that if I change the lye solution concentration, then I am changing the amount of NaOH. What they're not realizing is that you can use more or use less water to make that solution, while leaving the amount of lye exactly the same.

You are right in that concentration and percentage basically mean the same thing when talking about the lye solution concentration.

"... If I spill one of these on my hand, I want it to be the 25% not the 40% so I'll have a better chance of washing it off before it burns...."

Actually both will burn you equally as fast. Soapers deal with incredibly concentrated lye solutions compared with any other household or hobby use -- as high as would be used only in the chemical processing industry. Whether the lye is at 10% concentration or 50% concentration, the damage will be done in seconds. Only if the NaOH solution is very weak -- well under 10% concentration -- would you see a reasonable slowdown in the rate of damage.

Ohh, didn't I find this out the hard way when I first started soaping!

 

[TeresaT]

Thanks, DeeAnna. I didn't realize that about the solution. BTW, dumb but true story: I'm a visual learner more than anything else and it didn't connect until I was playing with SoapCalc one day with my favorite blend of oils. I was changing the lye concentration amounts and ratios at the top, but leaving the rest the same. The oz of NaOH never changed but the oz of water did along with the "concentration" percentage. When it finally dawned on me why, I couldn't stop laughing. I had been determined that I was going to find that concentration level that made the lye amount change!

 

[rparrny]

Well, I'm a visual person and the chart made me see more clearly the relationship between saturated and unsaturated fats and lye concentration and the effect on hardness and swirl. I just made a loaf with 33% lye for the first time and I found it easier for me to work with. I'm curious to see how the soap turns out.

 

[TeresaT]

I just made a loaf with 33% lye for the first time and I found it easier for me to work with. I'm curious to see how the soap turns out.

I found that to be my best level. Not too fast to trace and I can do swirls, but with high OO recipes, I'm not mixing forever. I hope your soap turns out well and you end up liking the 33% solution.

 

[rparrny]

I found that to be my best level. Not too fast to trace and I can do swirls, but with high OO recipes, I'm not mixing forever. I hope your soap turns out well and you end up liking the 33% solution.

Looking at that chart made me think that with my sat/unsat ratio, maybe my lye solution was not optimal for what I wanted. My last batch was so thin it looks like some dark halloween soap and although I used a very small amount of black that is all you seem to see. This batch was just right, not too thin yet didn't thicken quicker than I could work.

 

[cmzaha]

Carolyn, purely out of curiosity, in the bolded part, are you saying if you soap with tallow and shea in the same recipe or if you soap with either tallow or shea? I've yet to soap with tallow, but do use a small percentage of shea in my soaps and they behave fairly well at 33% at room temperature. If I soap hotter, it moves quicker of course.

In the same recipe since they both hasten trace

 

[cmzaha]

Looking at that chart made me think that with my sat/unsat ratio, maybe my lye solution was not optimal for what I wanted. My last batch was so thin it looks like some dark halloween soap and although I used a very small amount of black that is all you seem to see. This batch was just right, not too thin yet didn't thicken quicker than I could work.

Gorgeous!! I am completely in love with the colors and the eye I see in the soap.

 

[IrishLass]

I call 33% my "Goldilocks" concentration. Not too fast, not too slow, but just right ......at least for about 98% of my batches, that is.

Like Carolyn, I use a 40% concentration with 100% Castile's, and I increase my water to a lower concentration when working with finicky FOs (30% or 31%, depending), although I still keep it at 33% even when soaping my 'Veggie Con Carne' formula which contains lots of hard fats such as tallow, lard, hydrogenated PKO, and mango butter (plus 10.5% castor to boot)..... as long as I'm working with a well-behaved FO, that is, and my oil and lye temps aren't lower than 110F when I soap it. I've found that if those 2 aspects are in place, I have plenty of time to play.

To give you an idea of how much play time I have with the above formula, my most recent soap made with it was Soaping101's 2-tiered pencil line soap which took me a whopping 45 minutes to execute, and although my batter was getting pretty thick towards the end, it actually stayed very workable for me until I was 100% finished. The FO I used was TSW's Blue Sugar, which is an absolute dream to soap (I would never had attempted this with anything other than an absolute angel of an FO, btw):

IrishLass

 

[TeresaT]

IL, that is absolutely gorgeous!! It is like clouds and marble rolled into one! Awesome!!

 

[songwind]

Very nice. I always like having more information about the underpinnings of why we do things. Helps when you run into a new situation and you have to figure it out on your own.