Mixing Hydroxides

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golden_seal

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When mixing potassium and sodium hydroxide can you just calculate how much of each from the total amount of lye? So if I wanted 60% KoH and 40% NaOH and the total amount of KOH given (from soapcalc) is 3.33 could I just split the two? It would be 1.99 KOH and 1.33 NaOH. I started with 90% KOH on the calculator. Also, do you just add both to the liquid at the same time?
I found this calculator that I can use for dual hydroxide but still wondering about how to mix both.

http://soapee.com/calculator
 
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DeeAnna

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It really doesn't matter how you mix them. It will be fine -- nothing will blow up or catch fire if you put one into your water before the other or even put them both in at the same time.

No you cannot just take the weight of one lye and divide that weight between KOH and NaOH. There are different numbers of molecules per gram for each lye, so you will end up with the wrong total amount of lye to properly saponify your fats.

There are several ways to calculate a mixed lye recipe. You found one by using the Soapee calc that allows mixed lye recipes. The Summerbeemeadow calc does the same. If you end up having to use a calc that doesn't allow mixed lyes such as SoapCalc, you can still get the job done. Here's how --

You are going to calculate the exact same soap recipe twice. The only difference between the two versions is your choice of lye -- use NaOH as the lye for the first version and KOH as the lye for the second version.

TIP: If using soapcalc, be sure to put a check mark in the box for 90% KOH purity if needed for the KOH you are using.

For the first version, the recipe calculator will tell you how much NaOH that you would need to use if you wanted NaOH as ALL of the lye. In the second version, it will tell you how much KOH you would need to use if KOH was ALL of the lye.

The last step is to calculate the weights you really need for your specific recipe. Since you want a mixture of 40% NaOH and 60% KOH for the recipe, multiply the NaOH weight times 0.40. And multiply the KOH weight times 0.60. This will give you the correct weights of each lye to mix together to make the recipe.
 
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golden_seal

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Oh good! Thank you!! Now I can start the liquid soap I am wanting to do today
It doesn't want to come together. Is that normal? I've only tried the glycerine method and there was no issues at all when I made that. ImageUploadedBySoap Making1449266678.461467.jpg
ImageUploadedBySoap Making1449267027.485986.jpg
And now it's this. Maybe I should have looked up making it with dual lyes, lol. This recipe is
8.5oz lard
5oz olive oil
2oz castor oil
0.5 coconut oil
ImageUploadedBySoap Making1449267449.589607.jpg
Is this done? I'm sorry for so many stupid questions, lol. This was my first time using water instead of glycerine. Do I need to cook it longer like the glycerine? All this panic and it seems to have worked it so far ImageUploadedBySoap Making1449267801.382017.jpg
 
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golden_seal

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Yep no zap! I was expecting it to take so much longer but I'm assuming the NaOH made it faster! Awesome! I can't wait to try it out!

Thank you!
 

DeeAnna

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Yep, that's the old Snowdrift Farms calc. It works too, but this calc is on an archived copy of a long defunct website. I'd recommend sticking with calcs that are being actively maintained such as Soapee and SBM.
 
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