Possible Bug: Citric Acid calculation in hybrid soap

packl

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Jun 16, 2020
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Hey, first of all thanks for this great tool! It really is the best and most user-friendly soap calculator out there!

There seems to be an issue with calculating the additional lye needed then using citric acid in a hybrid soap.

When adding citric acid, the following additional amounts of lye (for every gram of citric acid) need to be considered.

1g citric acid = 0.624g NaOH
1g citric acid = 0.842g KOH


When using the NaOH calculation (solid soap) it is calculated correctly.
When using the KOH calculation (liquid soap) it is calculated correctly.

When using the NaOH + KOH calculation (hybrid soap) it is not calculated correctly.
It seems only the NaOH part of the lye is calculated and the KOH part is not added.

Thanks for looking into this.
 

packl

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There's no reasoning given in that article why it doesn't need to change.

Anyway, if I want to make a soap with a 60/40 ratio I want to keep that ratio that way, if I only add more NaOH it will skew the ratio. Therefore both types of lye need to be added in the appropriate amount.
 

packl

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Jun 16, 2020
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@Yooper

Have you heard any updates on this issue?

It's still calculated the same way, ignoring the ratios.
 

AnastasiaK

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Oct 1, 2020
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Hi, I wanted to ask if the sap number for citric acid is correct at all...
When i count recipe for
1000 g of olive oil, 0sf with no citric acid i have 134 g NaOH.
with additional 20g of citric acid the result is 143,15 g NaOH.
so sap number for 1 g of citric acid in soapmakingfriend is then 0,4575....
i had this number for several recipes...
can you please take a look?
 

Yooper

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Upper Peninsula of Michigan/ Florida Gulf Coast
It's not the sap number that is important- it's the amount of NaOH (a base) that is needed to neutralize the citric acid (an acid) (or rather vice versa, I guess!).
10 g citric acid neutralizes 6.24 g NaOH

Citric acid and Potassium hydroxide (KOH) make Potassium citrate in soap
10 g citric acid neutralizes 8.42 g KOH

I'm not a math person at all (that's why I use software), so I'd have to do some investigating to see if the calculator is off. I used it yesterday, and used 40 grams of citric acid, and today the soap seems ok (firm, and not zappy).
 

AnastasiaK

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Oct 1, 2020
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It's not the sap number that is important- it's the amount of NaOH (a base) that is needed to neutralize the citric acid (an acid) (or rather vice versa, I guess!).
10 g citric acid neutralizes 6.24 g NaOH

Citric acid and Potassium hydroxide (KOH) make Potassium citrate in soap
10 g citric acid neutralizes 8.42 g KOH

I'm not a math person at all (that's why I use software), so I'd have to do some investigating to see if the calculator is off. I used it yesterday, and used 40 grams of citric acid, and today the soap seems ok (firm, and not zappy).
Yes, i understand that. We use anhydrous form ( that wants 0,625NaOH) and monohydrous form ( that wants 0,571NaOH) here in the Czech Republic.
I have tried 3 recipes to count NaOH with calculator and by hand...
and always had differend result by hand from the one wth calc.
so i made 3 recipes with different oils, 0sf and +sf to see what will happen and so far i see 0,4575 in every case... that is the reason why i ask... because 0,4575 is different from both 0,625 and 0,571...
 

Yooper

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Sep 7, 2019
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233
Location
Upper Peninsula of Michigan/ Florida Gulf Coast
Yes, i understand that. We use anhydrous form ( that wants 0,625NaOH) and monohydrous form ( that wants 0,571NaOH) here in the Czech Republic.
I have tried 3 recipes to count NaOH with calculator and by hand...
and always had differend result by hand from the one wth calc.
so i made 3 recipes with different oils, 0sf and +sf to see what will happen and so far i see 0,4575 in every case... that is the reason why i ask... because 0,4575 is different from both 0,625 and 0,571...
Can you cut/paste a screenshot of the recipes so the developer can look at the formula and the results? I cannot recreate here on my end.
 

AnastasiaK

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Oct 1, 2020
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60

61

0sf for keeping it easy.
Using 20g of Citric acid. Number of NaOh needed is 0,4575 for 1 g od acid.
 

AnastasiaK

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Oct 1, 2020
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62

63

Again 0sf, only coconut oil, 30g of citric acid.
Differece in NaOh idś 196,91-183,18=13,73 for 30g of acid, so again 0,4575 for 1g of acid.
 

AnastasiaK

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Oct 1, 2020
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64

65

0sf, mix of oil, 20g of acid.
Difference: 152,24-143,09=9,15 for 20g of acid, which makes 0,4575 for 1 g od acid.
 

AnastasiaK

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Oct 1, 2020
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66

67

Mix of oils, 10Sf, 2% of oils -citric acid.
142,26-133,11=9,15 for 20g of acid, so again 0,4575....
 

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