# Lye calculation help needed.

Discussion in 'Lye-Based Soap Forum' started by Auxotroph, Sep 23, 2019.

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1. Sep 23, 2019

### Auxotroph

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Hello,

I have a big problem. I have a tried and true recipe that has 4535 grams oil weight with a 40% lye solution which is 384 g lye and 940 g water.

I want to resize my batch but when I plug the exact recipe in soap calc it tells me to use 646 g of lye in 969 grams of water which is a 66% lye solution.

I have ran this over all the lye calculators that I can find and they all don't give me a 40% lye solution.

What should I do to resize batch?

Thanks,
Matt

Last edited: Sep 23, 2019
2. Sep 23, 2019

### DeeAnna

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"...646 g of lye in 969 grams of water which is a 66% lye solution...."

No, that's a 40% lye concentration or a 1.5 water:lye ratio. I'd need to know your recipe to calculate "water as % of oils".

"...40% lye solution which is 384 g lye and 940 g water..."

And likewise, you're incorrect. That's a 29% lye concentration or 2.45 water:lye ratio. Ditto about "water as % of oils."

Lye concentration % = NaOH weight / (NaOH weight + Water weight) X 100
First example lye concentration % = 646 / (646 + 969) X 100 = 646/1615 X 100 =40%

Water:lye ratio = Water weight / NaOH weight
First example water:lye ratio = 969 / 646 = 1.5

I have no idea what your recipe is or how you're calculating it or what you're looking at when you claim the "lye solution" is 66% or 40% or whatever. You need to provide more information to get better help.

I wrote the following comment earlier today on another thread. This comment applies here as well, so I'm going to repeat myself here with slight edits --

I honestly do not know what you mean when you say "40% lye solution." I could assume it means "lye concentration" but I'd be guessing and would really have to ask to confirm. The phrase "lye solution" means any mixture of water + alkali (NaOH or KOH or whatever) but that's all it means. There are three terms that are commonly used to talk about lye concentration --

"The lye solution was 40% lye concentration"
"The lye solution was 40% water as % of oils"
"The lye solution was a 1.5 water:lye ratio"

"...4535 grams oil weight ... 384 g lye..."

I also have to say this amount of "lye" seems to be much too low for this quantity of fat if you're making a typical bath, shave, or similar soap. If your "lye" is NaOH (sodium hydroxide), the average NaOH saponification value for this recipe is 384/4535 = 0.085 g NaOH / g fat. The average NaOH sap value for a typical soap should be something closer to 0.13 to 0.15, give or take a bit.

Last edited: Sep 23, 2019
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3. Sep 23, 2019

### Auxotroph

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Hi,

The mixture is:
30% olive oil pomace
26% coconut oil
44% veg shortening

I was calculating the lye solution as being 40% lye and 60% water = 40% lye concentration.

I plugged in your calculation of 29% into soapcalc and it gave me 1581 g water and 646 g lye.

That is nearly double what I use in my batch.

I still can't find the problem. If I use a lye calculator and make a bigger batch and it ruins the batch, it will cost me too much money.

Is it possible to work out how much lye solution to use from the total batch size and then work out what concentration of lye solution to use?

I have used the C1V1=C2V2 concentration calculation, but it doesn't give reliable results in this case.

Thanks,
Matt

Last edited: Sep 23, 2019
4. Sep 23, 2019

### DeeAnna

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"...Is it possible to work out how much lye solution to use from the total batch size and then work out what concentration of lye solution to use?..."

I don't see why you need to do that -- you're overthinking the problem and making this way too hard. And, speaking frankly, I don't think you really truly understand what you're doing, so I advocate you stick with a simpler approach that is more likely to be accurate. Here is the method I would suggest you use with SoapCalc --

Step 1. Set up the original soap recipe with your original total fat weight of 4535 grams and your various fats in percentages. Enter whatever lye concentration you think you need -- I used 40%. Enter whatever superfat you want -- I used the default of 5%. Click the Calculate button and then click the View and Print recipe button.

Step 2. Verify your original recipe is correct. If you want less water in the recipe, go back to the calculation screen, increase the lye concentration percentage, and recalculate the recipe. Do not change anything else. Tweak the lye concentration until you are satisfied --

Step 3. When you are happy with your ORIGINAL recipe, go back to the calculation screen. Change ONLY the total fat weight (weight of oils) to the new total weight of oils. Do NOT change anything else -- don't fiddle with the lye concentration or the percentages of the individual fats. Recalculate and view the new recipe. It will be the same recipe, just a larger batch size.

Last edited: Sep 23, 2019
5. Sep 23, 2019

### Relle

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Not sure what veg shortening your using, I see your in NZ, if it's the same as in Oz ( copha) that your using, it's coconut oil, so you would be using a total of 70 % CO.

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6. Sep 23, 2019

### DeeAnna

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Thanks, Relle. I made a guess about the "shortening" being something like Crisco. The method to set up and calculate the recipe would be the same, whatever type of shortening the OP actually has.

Whether it's a Crisco type shortening or a coconut oil shortening, I have to say it's not a recipe I'd care to make ... or to sell.

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7. Sep 23, 2019

### Auxotroph

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Yea it is coconut based, but hydrogenated so it isn't really oil.

It is best for people with sensitive skin, which is my target market. I only ever thought about selling it because people were hounding me because the soaps down at the market are too harsh. That is why the lye amounts that the lye calculators suggest scare me. I am upscaling to go to the market to find more customers.

I have made pure olive oil caster soap but nobody likes it because it doesn't lather and it is expensive to make. I have also made olive oil, coconut oil and sunflower oil soap, that was OK but also expensive to make. Now I finally find a soap that is affordable enough to make to take to the market and you tell me it's horrible.

I am open to suggestions if you know a better more cost effective recipe for sensitive skin soap. Considering that you are the first person that I have ever talked to who makes soap, I would love for you to give me advice on how to make a sensitive skin soap that is cost effective to make in bigger quantities.

Last edited: Sep 23, 2019
8. Sep 23, 2019

### shunt2011

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Hello and welcome!

It doesn't matter if it's hydrogenated or not. It's still coconut and will be extremely stripping to the skin. I wouldn't touch it nor would I consider selling it to my customers. Lard, Palm, Tallow. Sounds like you need to do more homework before even considering selling. And as for good for sensitive skin. Almost any well rounded CP/HP soap would be okay for sensitive skin.

Also since you're new here hop on over to the introduction forum and tell us a bit about yourself.

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9. Sep 23, 2019

### Auxotroph

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Hello,

You are right, I do need to do more research on the subject before I hit the market.

Its ok, have plenty of time.

No lard, palm or tallow here though. Animal free, palm free and plastic free.

It is a long road to making the perfect soap.

On the bright side, removing the shortening will slash my batch time in half.

Anyways thanks, I appreciate the tips a lot.

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10. Sep 23, 2019

### penelopejane

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Look at the link below and go through it for recipes with oils you would like to use. You will also get lots of hints as to why your soap might not have worked.

If you OO soap isn't liked it is probably because it isn't a balanced recipe or that you hadn't cured it for long enough.

If the OO is too expensive to make soap in NZ then you aren't buying it in bulk. It is far cheaper than lard or tallow over there. Google NZ soap supplies.

Everyone's skin is different but there isn't a milder soap than pure OO after a 12 month plus cure. It is really annoying but you really have to do trial and error to find the perfect recipe for you, your suppliers and your environment.

I don't use Coconut oil in soaps I use but I do add it at 10% max for soap I make for others. Try Almond oil, macadamia nut oil, shea butter, cocoa butter.

You also have to learn about additives to tweek for hardness and reducing soap scum.
https://www.soapmakingforum.com/forums/recipe-feedback.34/

Also look on this site for recipes and fabulous videos on how to make soap.
http://www.soaping101.com/

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11. Sep 23, 2019

### DeeAnna

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I have to say you are not ready to make big batches of soap and you are not ready to sell. You are talking about making huge batches of soap that are going to be harsh on regular skin and utterly awful for sensitive skin. I understand why you're asking for a recipe, but honestly you need a better grasp of the basics of soap making more than you need a recipe handed to you.

"...the lye amounts that the lye calculators suggest scare me..."

I take it you were making soap using "...4535 grams oil weight ... 384 g lye..."? If so, your soap was awful because there was way, way, WAY too much unsaponified oil in the recipe. I'm not surprised you say it didn't lather well -- the product was mostly fat, not soap.

If you want to make decent soap, you have to learn to use a soap recipe calculator and to follow the recipe as calculated. You can't just "wing it" and expect the soap will turn out well.

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12. Sep 23, 2019

### Auxotroph

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Hello.

Most of the recipes on the my favourite recipe are pretty much exactly the same but using palm oil instead of shortening.

My soap lathers fine, cures hard, gets to trace fast and it leaves a layer of oil on the skin that saves having to cover your skin in olive oil after you shower. If you have ever read the bible it always talks about covering your skin in olive oil after bathing.

I have been making soap for about ten years and have made that recipe probably 70 or 80 times, it makes about 20-25 170-200 gram bars.

I am not really interested in shea butter and all those other butters because I am a microbiologist, so I know those types of ingredients are a breeding ground for bacteria. Coconut oil is my antibacterial agent in the soap.

Olive for moister, coconut for antibacterial and shortening for bulk and hardness.

I only recently started making it with coconut shortening, I was making it with palm shortening. Then I felt guilty for all the monkey habitat that palm trees are destroying.

I will continue looking for some thing that can replace the shortening.

13. Sep 24, 2019

### penelopejane

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I donâ€™t know what shortening you are using. I guess a type of margarine or a hydrogenated oil? Iâ€™d personally prefer natural Shea butter. But thatâ€™s just me. The butters add something special to soap at only 10% and leave the skin feeling wonderful...unlike coconut oil.

14. Sep 24, 2019

### Auxotroph

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What antibacterial agent do you use? If you aren't using anything that kills bacteria, then the soap isn't really cleaning you.

15. Sep 24, 2019

### penelopejane

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I do not believe that at all.
Some bacteria actually benefit us. The normal population of bacteria on our bodies not only eats our sweat but also helps defend us against truly harmful, invasive bacteria.

16. Sep 24, 2019

### Lin19687

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???

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17. Sep 24, 2019

### jcandleattic

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Soap by it's very nature is "anti-bacterial" so I don't understand this statement.
No additional anti-bacterial agent is necessary...
???? Ummm, what? Due to the make-up of coconut oil, it's more cleansing than most other oils, but that does not mean it's anti-bacterial...

Olive oil, as an oil may be moisturizing, but once in soap it is not. It is less stripping than other oils, but again, soap, by it's very nature is not 'moisturizing' but cleansing.

I'm thinking you may need to continue with some research and get some better understanding of what you are doing.

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18. Sep 24, 2019

### Auxotroph

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You have to first understand how horrible soap is at a microbiological level. They wash all the dirt and grime off your body then they sit around for the rest of the day in perfect conditions for them to multiply. If you use a oil that has microbiological properties, it reduces this.

Here is what health line has to say about it.

https://www.healthline.com/nutrition/coconut-oil-and-skin#section2

Let me know if you find an oil with better antibacterial actions than coconut oil.

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19. Sep 24, 2019

### DeeAnna

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20. Sep 24, 2019

### jcandleattic

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But you are comparing apples to oranges.

Once an oil goes through the saponification process it is no longer an oil, but soap. Due to the pH level of handmade soap, it is, as I stated earlier, by it's very nature, anti-bacterial.

The article you quoted is specically speaking about coconut OIL and not COCOS NUCIFERA which is saponified coconut oil.

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