The mysteries of the lye calculator

[topofmurrayhill]

There aren't any! What it does is dead simple. You can create your own calculator pretty easily if you're good with a spreadsheet.

Say I want to make a batch with 500 g oils and this recipe:

20% CO
50% Lard
20% OO
10% Castor

Let's do it manually.

500 x .20 = 100 g CO
500 x .50 = 250 g Lard
500 x .20 = 100 g OO
500 x .10 = 50 g Castor

I multiplied the total oil weight by the various percentages to get the amounts of the individual oils.

100 x .183 = 18.3 g
250 x .141 = 35.3 g
100 x .135 = 13.5 g
50 x .128 = 6.4 g

I multiplied the oil amounts by the NaOH SAP value to get the amounts of NaOH for each oil. The total is 73.5 g NaOH.

Want a 5% lye discount? 73.5 x .95 = 69.8 g NaOH.

What about water? If I want to use a 33% lye concentration, it's (69.8 / .33) - 69.8 = 141.7 g water.

3% fragrance is 500 * .03 = 15 g.

Ready to soap!

 

[artemis]

Oh, my! Math! I am having heart palpitations just reading your post! But my husband and daughter will be very interested in seeing this.

 

[Arimara]

I'll use math only when I need to. I can't stand excessive work with numbers.

 

[topofmurrayhill]

I know Teresa could ace this.

 

[TeresaT]

There aren't any! What it does is dead simple. You can create your own calculator pretty easily if you're good with a spreadsheet.

Say I want to make a batch with 500 g oils and this recipe:

20% CO
50% Lard
20% OO
10% Castor

Let's do it manually.

500 x .20 = 100 g CO
500 x .50 = 250 g Lard
500 x .20 = 100 g OO
500 x .10 = 50 g Castor

I multiplied the total oil weight by the various percentages to get the amounts of the individual oils.

100 x .183 = 18.3 g
250 x .141 = 35.3 g
100 x .135 = 13.5 g
50 x .128 = 6.4 g

I multiplied the oil amounts by the NaOH SAP value to get the amounts of NaOH for each oil. The total is 73.5 g NaOH.

Want a 5% lye discount? 73.5 x .95 = 69.8 g NaOH.

What about water? If I want to use a 33% lye concentration, it's 69.8 / .33 = 211.5 g water.

3% fragrance is 500 * .03 = 15 g.

Ready to soap!

Hahahaha. You make me laugh, TOMH. That looks almost as easy as balancing an elephant on the head of a pin. Because some people (

) suck at math and haven't a clue about spreadsheets.

ETA: Although, thanks to you and your wonderful math lessons, I am getting much better...

I know Teresa could ace this.

HA! LMBO!!! You snuck this in while I was writing my snarky comment to you!!!

 

[Arimara]

I know Teresa could ace this.

Good for her. I'll save the math for baking, where I won't think that it's math because it's much more fun and yields better results. Too bad I can't make a cheese cake now because it would be in my belleh as we speak. I'll get around to making lemon curd instead.

 

[ngian]

What about water? If I want to use a 33% lye concentration, it's 69.8 / .33 = 211.5 g water.

I think that if the amount of NaOH needed is 69.8gr and we want to make a 33% lye concentration the water would be two times the NaOH weight and that is 139.6gr

211.5 (or better 69.8 x 3 = 209.4gr) is the total grams of the lye solution (water and NaOH)...

So I think that the math for calculating water is not NaOH weight /.33 but something like:

water = (NaOH weight / .lye concentration number) - NaOH weight

water = (69.8/.33)-69.8

:think:

 

[topofmurrayhill]

water = (69.8/.33)-69.8

Thank you, that's the right formula.

 

[Lion Of Judah]

these formulas are very important to know . there is no guarantee that we will always have access to the creature comforts that makes our lives easier i.e an online lye calculator. good looking out topofmurryhill , i got to put this someplace for safe keeping .

 

[dixiedragon]

OMG! It's 8:30 on Monday! I'm proud of myself for finding and wearing clean pants!

 

[Obsidian]

I think my brain just died a little

 

[Steve85569]

Now I need to write down the (average) SAP values for oils that I use and simply set up an Excel ( Libra Calc) spreadsheet. No need to over complicate the spreadsheet, I can keep it down to the oils I use and not include the ones that I don't.

I can now have several pages on the book that contain my usual recipes and leave room for notes.
A simple way of helping to organize recipes!
Thank you TOMH!

 

[Steve85569]

I have set up a simple spreadsheet but I need to modify the calcs so I can simply add or subtract oils from the mix. I did not use the v or h lookup functions - just kept it a straight forward simple calculation. I'll keep working on it and keep it as simple as possible.

PM me if you are interested.

 

[LisaAnne]

Ha, as soon as I read this I was looking for Teresa to comment. Thanks for the information! As a stated above it is important to be able to calculate a soap recipe. I will give it a try after I work the process out in my head and understand it. Thanks

 

[reflection]

murray (that's your new name ),

this is great. i was trying to figure out the SF from a recipe and by the time i realized i needed to add up all the lye amounts i was too tired to do it. i was starting in the wrong place. this makes it all more understandable.

Now I need to write down the (average) SAP values for oils that I use and simply set up an Excel ( Libra Calc) spreadsheet. No need to over complicate the spreadsheet, I can keep it down to the oils I use and not include the ones that I don't.

I can now have several pages on the book that contain my usual recipes and leave room for notes.
A simple way of helping to organize recipes!
Thank you TOMH!

here's a page from a library book i keep checking out. i can't seem to get it to print any darker but hopefully you can still read it.
[URL=http://s970.photobucket.com/user/reflectionlj/media/soap/SCN_0004%20copy.png.html] [/URL]

 

[Susie]

The smoke y'all see wafting from Texas was my brain...

 

[Steve85569]

I have an inter active spreadsheet using 44 oils. Well not really44 oils because of bees wax, meadow foam and pine tar but you get the picture.
Seems to work for me and there was no need for me to fry my brain. I did have a job making custom spreadsheets more than once though...
Thanks TOMH for getting me going and DeeAnna for the links.

Susie, I'll send you a copy if you would like. The only favor I would ask is feed back whether good or bad and suggestions on changes.

Steve

 

[The Efficacious Gentleman]

All this has encouraged me to make my own. I can choose the type of "lye" that I want and it looks up the SAP accordingly, as well as adjusting for lye discount and so on. It also works out how much citric acid and extra lye I need. Needs some tidying, but it works okay. Thanks for the peer pressure

 

[Susie]

I have an inter active spreadsheet using 44 oils. Well not really44 oils because of bees wax, meadow foam and pine tar but you get the picture.
Seems to work for me and there was no need for me to fry my brain. I did have a job making custom spreadsheets more than once though...
Thanks TOMH for getting me going and DeeAnna for the links.

Susie, I'll send you a copy if you would like. The only favor I would ask is feed back whether good or bad and suggestions on changes.

Steve

I really would appreciate it! I will be happy to send suggestions and critiques as needed.