# Castile 95%NaOH 5%KOH calculations help

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#### earlene

##### Grandmother & Soaper
Supporting Member
To make a soapmaker's classic castile that lathers nicely, lasts a long time, and only requires a 4-6 week cure --> use 100% olive oil, whatever lye solution concentration you prefer, the usual 5% superfat (lye discount), and a blend of 95% NaOH and 5% KOH (potassium hydroxide).
The KOH makes the soap more soluble in water. Thsi means the usual stringy oleic soap gel doesn't form as easily with a KOH-NaOH castile as it does with a castile made with NaOH only. I won't debate the "cure faster" issue -- all I will say is if you want to make a true castile (100% olive oil) and would like it to last a long enough time, make lots of nice lather, and be mild to the skin after a more typical 4-6 week cure, then try using the mixed lyes.

I really want to try this, but I am having a very hard time trying to adapt my [50% lye] masterbatch to say, a 40% lye concentration, particularly with the added KOH.

Using the advanced search I have been unable to find any answers to this question. It doesn't mean they are not here, but I just cannot find them.

I think I can do the calculations for a 40% concentration easily enough with just NaOH, but with a 5% KOH and 95% NaOH, how would I do this? I am at somewhat of a loss. Do I use the NaOH water and ignore the KOH water recommendations? Or is there a formula for figuring out how much water for the KOH separate from the amount needed for the NaOH, thus having to add the two together?

Well this is how far I have gotten so far:

95% NaOH for this 32 ounces of OO = 110.9 grams
5% KOH = 9.1 grams (per Soapee) Or is it 8.1 grams (I get 8.1 if I use the 0.713 number as the divisor in this post)

That's about as far as I get, because I don't know where to go with the water.

Soapee says to use 179.9 grams of water total. Okay, so if I do that, then here's what I will do with my 50% masterbatch:

221.8 grams of 50% Lye solution
69 grams of additional distilled water
9.1 grams of KOH (per Soapee) BUT other calculations lead me to 8.1 grams (1.403 as a multiplier or 0.713 as a divisor)

Both MMS & SummerBeeMeadow also come up with 8.1 grams KOH, so I am thinking 8.1 grams is correct and not the 9.1 I get in Soapee (or maybe that's because the KOH is set at 90% purity in Soapee?)

Which of these numbers correct for the KOH?

Is the additional water amount correct, and how does one determine that for a mixed lye soap?

~ ~ ~ ~
Also at one point I think I found a post where someone (don't remember who, but I think it was one of the more sciene-minded members) posted a little chart about how to figure out how much water to add to a 50% lye pre-mix (masterbatch) solution to come up with respective concentrations. I believe it listed them like for 40% add, for 35% add, like that. Anyway I can't find it now and I thought I bookmarked it. So perhaps it was my imagination.

#### Saponomancer

##### Professional Geek
Usually I do mine as a ratio of lye to water so like 1:1 1:1.5 1:2 1:3, if I'm not mistaken you want something like 1:1.5 for the concentration you're considering, so it would be the full weight of both of the lyes together X 1.5, and that's your water.

Edit: pardon, so basically you would calculate how much is already in there via 1:1 on the first lye, then subtract that from the new number, and add whats left to your solution

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#### The Efficacious Gentleman

Supporting Member
I would also look at making two 50% solutions, based on the amount of each lye needed, then just use extra water to get it to a 40% solution water amount based purely on the NaOH. With just 5% KOH, the difference in actual grams of water won't be massive

#### ngian

##### Well-Known Member
Well DeeAnna has motivated me too these days with the Dual Lye Castile, and I'm planning to make one with some old olive oil (that I want to get rid of) and actually add a little of coconut.

Here is my recipe:

Olive: 95% - 475gr
Coconut: 5% - 25gr
Water (38% Lye Concentration): 114,8gr
NaOH 95%: 64.8gr (purity 98%)
KOH 5%: 5,5gr - (purity 85%)
Lye Discount: 2%

This is what an excel file that I have gave me, which has the ability to set purities for both NaOH and KOH in a dual alkali recipe.

The logic with the water amount is to take the amount of NaOH and find the water based on your lye concentration, then do the same with KOH to find its amount of water needed based again on your lye concentration, and finally add those two water amounts.

So in my above recipe:
NaOH 64,8gr x 1,632 = 105,75gr
KOH 5,5gr x 1.632 = 8,97gr
Total water: ~144,72gr
(1:1,632 is the ratio of water based in the 38% lye concentration)

As far as it concerns your case you will need
221.8 grams of 50% NaOH Lye solution and add to that 55,45gr of water in order to have a total of 110,9gr NaOH and 166.35gr of water (1:1.5 ratio)
and then add KOH 9,1gr with 13.65gr water.

Hope I helped you a little, and I also hope to find some time this week.

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#### DeeAnna

##### Well-Known Member

You say MMS and SBM call for 8.1 g KOH and Soapee calls for 9.1 g KOH. This is most likely due to different assumptions for KOH purity and differences in the saponification values in each calculator.

SBM is set to about 95% purity and Soapee is at 90% purity. I'll have to check MMS again and confirm what purity their calc is set to nowadays.

I think most people most of the time are getting more reliable results when using 90% purity, so I'd recommend the KOH weight based on 90% purity (Soapee's answer).

***

Total water for the batch is based on the total weight of both lyes. Your math is correct in your first post for the amount of extra water you need to use in addition to the water in your 50% NaOH masterbatch to end up with a 40% lye concentration.

***

If you want to calculate the total water required based on the lye weights, just to double check, here is how to do it --

Total lye weight = NaOH weight + KOH weight
Total water weight = (Total lye weight) * 100 / (Lye concentration percent) - (Total lye weight)

Using your numbers from Soapee --

Lye concentration percent = 40
Total lye weight = 110.9 + 9.1 = 120 g
Total water weight = 120 * 100 / 40 - 120 = 180 g

You said "...Soapee says to use 179.9 grams of water total...." So my answer is a fraction of a gram off of Soapee's number, but it's close enough.

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#### earlene

##### Grandmother & Soaper
Supporting Member
Thank you all for taking the time to answer. That helps a lot. I see everyone comes up with the same answer, so that is reassuring!

I like having the equations to work with as back-up. Thank you for providing the equation, DeeAnna. I have saved your response for future reference because I can see that the equation will come in handy. I have also saved the recipe & will be making it today.

Thank you again, everyone!

#### earlene

##### Grandmother & Soaper
Supporting Member
I would also look at making two 50% solutions, based on the amount of each lye needed, then just use extra water to get it to a 40% solution water amount based purely on the NaOH. With just 5% KOH, the difference in actual grams of water won't be massive

Gentleman, I had thought of that. I am not sure I am ready to start keeping a KOH masterbatch solution, though. Just having both dry lye solutions in the same bucket for storage has me feeling more cautious (a good thing, of course). If I put a KOH pre-mix solution into the mix I fear I may one day use the wrong solution to make soap.

Well, I could do the same as I did for the dry solution. I bought some kiddy bandaids & put them on the tops of the KOH to differentiate them from the NaOH. I know, kiddy bandaids!?! Well, a small package cost a lot less than Brightly colored Duck Tape, which was what I was going to do. I don't have any small children around, so it seemed to be just as efficient a method for differentiating the two different lyes from each other. Anyway, if I decide to make a KOH masterbatch, I could use the same kiddy bandaid ID method on the top of the bottles. I'm pretty sure that would work for me.

Still, I am not sure how often I would be using the KOH. Has anyone used the dual lye method with soaps other than castile? I see ngian is looking to do a bastile with dual lye.

Well DeeAnna has motivated me too these days with the Dual Lye Castile, and I'm planning to make one with some old olive oil (that I want to get rid of) and actually add a little of coconut.

Here is my recipe:

Olive: 95% - 475gr
Coconut: 5% - 25gr
Water (38% Lye Concentration): 114,8gr
NaOH 95%: 64.8gr (purity 98%)
KOH 5%: 5,5gr - (purity 85%)
Lye Discount: 2%

This sounds very interesting. I do hope you post your results. I wonder if how noticeable a difference there is from the traditional single lye soap vs the dual lye soap with this recipe. Are you going to do a control batch, too for comparison?

#### The Efficacious Gentleman

Supporting Member
I meant just simply taking your required weight of KOH and mixing it with enough water to dissolve it, same with the NaOH, then add more water - not making a massive amount of 50% to keep for other times

#### ngian

##### Well-Known Member
This sounds very interesting. I do hope you post your results. I wonder if how noticeable a difference there is from the traditional single lye soap vs the dual lye soap with this recipe. Are you going to do a control batch, too for comparison?

You are right, I must do a control recipe with NaOH only so as to estimate the benefits of dual alkali soap...

#### Arimara

Supporting Member
Well DeeAnna has motivated me too these days with the Dual Lye Castile, and I'm planning to make one with some old olive oil (that I want to get rid of) and actually add a little of coconut.

Here is my recipe:

Olive: 95% - 475gr
Coconut: 5% - 25gr
Water (38% Lye Concentration): 114,8gr
NaOH 95%: 64.8gr (purity 98%)
KOH 5%: 5,5gr - (purity 85%)
Lye Discount: 2%

This is what an excel file that I have gave me, which has the ability to set purities for both NaOH and KOH in a dual alkali recipe.

The logic with the water amount is to take the amount of NaOH and find the water based on your lye concentration, then do the same with KOH to find its amount of water needed based again on your lye concentration, and finally add those two water amounts.

So in my above recipe:
NaOH 64,8gr x 1,632 = 105,75gr
KOH 5,5gr x 1.632 = 8,97gr
Total water: ~144,72gr
(1:1,632 is the ratio of water based in the 38% lye concentration)

As far as it concerns your case you will need
221.8 grams of 50% NaOH Lye solution and add to that 55,45gr of water in order to have a total of 110,9gr NaOH and 166.35gr of water (1:1.5 ratio)
and then add KOH 9,1gr with 13.65gr water.

Hope I helped you a little, and I also hope to find some time this week.

I'm going to warn you to be careful and be prepared for a possible soap-on-a-stick. I made a batch of 100% avocado oil soap using this method and it REALLY (can't stress that enough) did not need to be stickblended. It went to thick trace in a few seconds and that was for both -SF and 0 SF. I haven't tried with a 5% superfat and I did note that it took only slightly longer with to trace with the 0% (really a few seconds longer).

So, be careful and be prepared.

#### ngian

##### Well-Known Member
I am aware of this Arimara, and the whisk is my friend.

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#### DeeAnna

##### Well-Known Member
The KOH adds solubility to a soap. This will be helpful for high oleic soaps (in other words, 100% olive castile and high OO bastile soaps) to quickly break down the goopy (snotty) oleic gel that forms with these soaps. It might also be helpful with a high stearic-palmitic (lard, tallow, palm) soap to help this type of soap dissolve and lather more easily. So I could see a bit of added KOH being useful as an alternative for some or all of the coconut oil or PKO in a recipe. I'm not sure how useful KOH will be in a highly soluble recipe, however, such as a soap high in PKO or coconut oil.

I have continued to test the mock castile soap I made with HO safflower and 5% KOH. I regularly compare this soap (8 weeks old by now) to a 2 year old castile made with 100% NaOH. The 5% KOH mock castile lathers much easier and more abundantly than the 100% NaOH castile. It has remained hard and long lasting with the usual precaution of keeping it in a well drained soap dish -- same as I do for all my soaps. The mock castile still has some of the nature of a 100% NaOH castile -- the lather is fairly dense and creamy and the wetted soap bar has the unusual slickness I associate with a high-oleic soap, but there is little or no tendency to make "snot" or slime.

I need to make a video....

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#### Arimara

Supporting Member
I am aware of this Arimara, and the whisk is my friend.

Sorry for bugging ya.

#### earlene

##### Grandmother & Soaper
Supporting Member
Castile Dual Lye - 95%NaOh 5%KOH [40%Lye] - Results

I made two batches of this yesterday. Dual Lye Castile - 95%NaOh 5%KOH [40%Lye Concentration]

One batch was 50% Pomace OO and 50% Kirkland's Pure OO. Within a few hours it was rock hard! I was amazed even though I read that it would be, I still found it remarkable. I did NOT use my SB because of the pomace, only a spoon. Trace at about 7 minutes, but I should have stopped stirring at emulsion to separate & mix colors, because by the time I was ready to pour into the mold it was already at thick trace and my ribbon pour did not turn out ribbony.

I used 3 micas from Steph's Micas & More: Sunflower Yellow, Clementine & Orange Coral, plus the plain soap batter as one of the colors; scented with Mad Oils Grow a Pear Tree FO and Candlepro's Pearberry (50/50).

Even though the 'ribbon pour' was a failure as such, I still think they are quite nice looking, and they smell very nice, too.

Mixing temps about 110F. CPOP'd with oven wall temp at 137F when I put them in (oven was pre-heated to lowest setting & turned off.)

The other batch was 100% Kirkland Olive Oil and although I thought I did everything else the same, except bringing only to emulsion before mixing colors and waiting for light trace before pouring batter into long-spouted container, it did not turn out at all hard as I was expecting.

Maybe the mixing temps were different, as I did not write them down & don't remember. I doubled the recipe for this one, but double checked all my measurements at every turn. I did run into a problem with pouring the batter, in that being a double recipe, it was too much for my container. So the first mold (a one-pound mold) did not get an even shake at the ribbon pour. The bottom portion was more like dump it in fast before it spills all over the place. Ribbon pour on top was a bit more like intended, but not what I expected. I am not sure how many times I am going to have to try it before I am happy, but that's another story.

The other mold is a long wooden mold and I have not yet unmolded it because the soap in the one-pound mold is still so soft.

I CPOP'd these overnight, going into the oven at approximately the same temp as the other one had, covered both molds with cardboard & a light towel.

For color I used 5 micas + TD for a 6 color ribbon pour, and scented with BeScented's Strawberry Patch FO. Micas from Steph's Micas & More: Cosmic Purple, Silver Graphite, Vivid Violet Neon, Marvelous Magenta Neon, Radical Red Neon; plus one portion was colored with TD, for a total of 6 colors.

So far I only have pictures of the one-pound mold cut. You can see how soft they are as evidenced by the edges:

#### earlene

##### Grandmother & Soaper
Supporting Member
I just realized this probably should be in the Recipes Feedback section instead of Recipes and Tutorials section. If an admin feels that is the more appropriate location, please move this thread. Thank you.

#### ngian

##### Well-Known Member
If everything was the same between the two batches except from the pomace OO that was used, then this might be to blame as pomace has the ability to hasten saponification because of the bigger amount of free FAs it has, and thus the soap peaks to a higher temperature, saponifying more quickly the oils and maybe forcing more water to evaporate because of the heat at the same time. I think also light or thick trace affects a little the unmolding time.

Those issues must be the reasons for the harder version of soap.

Yesterday I made the two lye solutions too (dual lye and NaOH only at 38% lye concentration) and by tomorrow I will make the soaps (will post in a new thread).

#### earlene

##### Grandmother & Soaper
Supporting Member
If everything was the same between the two batches except from the pomace OO that was used, then this might be to blame as pomace has the ability to hasten saponification because of the bigger amount of free FAs it has, and thus the soap peaks to a higher temperature, saponifying more quickly the oils and maybe forcing more water to evaporate because of the heat at the same time. I think also light or thick trace affects a little the unmolding time.

Those issues must be the reasons for the harder version of soap.

Yesterday I made the two lye solutions too (dual lye and NaOH only at 38% lye concentration) and by tomorrow I will make the soaps (will post in a new thread).

I suspected as much, but not at such a large degree of difference between the two batches. I do believe I will use at least one-quarter to one-half pomace in castile from now on because it made such a great difference. Although I still would want just as long a cure time, I really like being able to free up my mold, and to put soap out to cure without fear of defacing the bars with fingerprints, etc. I really like not having squishy bars of soap to handle!

I am looking forward to seeing your dual lye soap, ngian.

#### penelopejane

Supporting Member
Thank you.

I like the way the second soap turned out with the multi colours confined to the top of the soap. It might have been too much if the entire soap was like that rather than a highlight. Well done with your experiment.

#### earlene

##### Grandmother & Soaper
Supporting Member
I like the way the second soap turned out with the multi colours confined to the top of the soap. It might have been too much if the entire soap was like that rather than a highlight. Well done with your experiment.

Thank you, penelopejane.

That happened because I
1. poured the batter into the spouted container too thin, and
2. overfilled the spouted container and before it could start spilling over, I had to dump a lot of the batter into this mold immediately.

It's sort of funny because there was a split second of time from when my brain recognized it was going to spill over before my motor control kicked in. So I knew it was going to happen, but couldn't stop myself fast enough. My brain to motor control reaction time seems to be slowing down, so I'll need to remember to be more cautious.

Anyway the colors in the bottom of the mold got a bit muddled, then I as I began to pour slowly and carefully into the bigger container, the batter started to thicken. I actually filled most of the other mold before I finished the rest of this one, so the top layer had a better chance of staying where it was put without mixing in with the rest.

I'd like to get that wood grain look that newbie got in her green soaps, but I think neon colorants are not the best option for that. I'll try again with more subdued colors as I do have a few more micas to test.

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