Miller's Homemade Soap Pages:

Soapsheet Notes and FAQ

Generously contributed by Chris Mathes 

Hi, just a few notes about this template, how to use the workbooks created from it, and the methods used for certain operations. There's a short FAQ at the very end of this document.




(These instructions are based on installing the template for use by MSExcel97, on a machine running MSWindows95/98/ME/NT.)

The best place to keep this template is in your Templates folder. Your Templates folder should be in the folder in which you installed Microsoft Office or Microsoft Excel. For example: on my machine the Templates folder is 'C:\Program Files\Microsoft Office\Templates'.

Basic Usage

Once you have saved the template to your Templates folder, here's how to create new workbooks from it:

1) Start Excel
2) Click 'New' on the 'File' menu, which opens up the 'New' dialog box.
3) On the 'General' tab of the 'New' dialog, pick 'soapsheet.xlt'.
4) Click the OK button.
5) A new workbook called soapsheet 1 should appear in Excel.

There are only two worksheets in this workbook that you need to be concerned with when you play with your soap recipes. They are the sheets labeled "Recipe Worksheet" (the one you're on by default when you create a new workbook from the template) and "Scaled Version". The fields that may be changed on the Recipe worksheet are:

Entering a recipe is as easy as picking oils from the dropdown list attached to the Oil fields and entering the amount of each you want to use. Then, if you want, enter superfatting oils the same way, enter a lye discount, and perhaps change the bar size. That's it. Everything else will be calculated for you.

The Scaled Version sheet allows you to take the recipe entered on the Recipe sheet and scale it to whatever batch size you want. It shows everything from the Recipe sheet except INS values, and includes the additional field "Scale Factor". Scale Factor is the only field that may be changed on the Scaled Version sheet, and is used as follows: to scale a recipe down to one half of its original size, enter a Scale Factor of .5. To double a recipe, enter a Scale Factor of 2. Enter whatever factor you want, 2 and .5 are just examples. You get the idea.

New feature on Scaled Version worksheet: there are now three new fields that allow the recipe to be scaled either to a total batch size in ounces, a total batch size in ounces after cure, or a total number of bars based on the user settable bar size. To use these, enter a number in any one of the three fields (after typing the number hit return or select another cell to complete your change), then click on the button next to the field. This will cause Excel to automatically change the scale factor to achieve the batch size or number of bars you specify. Please note that this "goal seeking" feature of Excel is not perfect, sometimes it will not be able to properly scale to the number you specify. If that happens, try fractionally changing the number in one direction or another and then hit the button again. For example, if Excel is having trouble scaling your recipe to a 64 ounce batch, try scaling to 64.1 or 63.9 ounces instead. If it still doesn't work, try changing the number a little more. Also note that scaling to a batch size after cure or to a number of bars is disabled when the alkali is set to KOH (liquid soap).

Bar Soap (NaOH) versus Liquid Soap (KOH) Recipes

The alkali for a recipe is set to NaOH by default. If you change it to KOH for a liquid soap recipe, several things change:

1) The SAP values used change to those for KOH.
2) The water calculation changes to one suitable for liquid soap recipes.
3) The INS values and the INS calculation disappear, since the are not applicable to liquid soap.
4) Other fields/calculations that are not applicable to liquid soap (e.g. weight after cure, bar size, and yield in bars) also disappear.

SAP Values

The SAP values used in calculating the lye are looked up from the SAP Values worksheet. If you disagree with any of the values, please feel free to change them. You may also change the names of any of the oils, just make sure you change any references on the Recipe worksheet from the old name to the new name.

You may also add new oils, as long as you don't change the format of the SAP Values worksheet (this is very important, as the lookup from the Recipe worksheet depends upon the oil names and SAP values being in specific columns, and within a certain range of rows). If you do add new oils, you can either insert them into the list where you want or put them at the end; order is not important, just don't go past row 200 or so. Note too that the oils in the drop down list on the Recipe sheet appear in the same order as on the SAP Values sheet, so if you don't insert new oils in alphabetical order, they won't appear that way in the list either. To save any changes/additions you make to the SAP Values worksheet, so that any new workbooks you create will include them, see "Changing the template" below.

INS Values of Recipes

The concept of INS values is borrowed from Dr. Robert McDaniel's book, "Essentially Soap." He in turn borrowed it from an unattributed source. In any event, what he says is that an oil's INS value is based on its SAP value and iodine value, and that a soap's INS is the weighted average of the INS values of its constituent oils. What does that mean to you? Probably not much. The important thing is that (as related by Dr. Bob) the 'ideal' INS value to shoot for when formulating a soap recipe is 160. Now remember: 160 is only the ideal. Most recipes, even really excellent ones, won't be at an INS of 160. The majority of the ones I've looked at are in the mid 140's or low 150's. The INS value's real utility is as a sort of rough gauge of how well your recipe is balanced. In other words, if your recipe's INS is much above or way below 160, you might want to take another look at things. Note that the INS calculation is not done for liquid soap recipes.

INS Values of Individual Oils

Many of the INS values for individual oils are borrowed from Dr. Bob. Specifically, the sheet calculates its own INS values based on the best SAP and iodine values I could find, but where Dr. Bob had a value, I defer to him. You may note that a few of the oils listed have no INS. That's because Dr. Bob didn't list them, and I couldn't find iodine value numbers for them either. You can still use those oils in your recipes, but they will be ignored in the INS calculation for the recipe as a whole.

Canola Versus Rapeseed Oil

All canola oil is rapeseed oil, but not all rapeseed oil is canola. The reason for this is that rapeseed oil normally has an erucic acid content of up to fifty percent, while in order for an oil to be called canola, it may have an erucic acid content of no more than two percent. In other words, canola is low erucic acid rapeseed oil. What does this mean to you? Well, the erucic acid of regular rapeseed is largely replaced by oleic and linoleic acids in canola, which CHANGES THE SAP VALUE. I have yet to see a saponification chart, either published or on the web, which takes this into account. Every one of them treats rape and canola interchangeably, and lists the SAP of regular rape, even though the availability of regular rapeseed oil to the average North American consumer is limited at best. Is this dangerous? Since the SAP of rape is lower than that of canola, no, not really. It just means you're building an additional lye discount into any soap that uses canola. Which isn't much of a problem unless your recipe is already at the extreme of superfatting, or you're trying to make transparent soap. Bottom line: use canola for canola, and any of the other names (ramic/rape/rapeseed) for regular rapeseed oil.

Lye Calculation and Rounding

Because most people don't have a way to accurately measure amounts smaller than .1 ounces (well, I don't), the calculated amounts for lye and water are rounded DOWN to the nearest .1 ounce. If you must round, rounding down is the only safe way to go for lye, and unless you are making very small batches, a difference of less than one tenth of an ounce should have very little effect. Note that you may still enter amounts of oil to any level of precision you want, you just won't ever get more than one decimal place of precision for the lye and water.

Water Calculation

The amount of water required is calculated based on the rule of thumb of one pound of water for every three pounds of oils. There are other rules of thumb out there, e.g. six ounces of water per pound of oils, ala the MMS calculator, but I prefer the 1:3 rule. For liquid soap recipes the amount of water is three times the total weight of the KOH.

After Cure Calculation

The After Cure weight is an estimate of the total yield of soap after most of the water has cured out of your bars. It is based on the rule of thumb that when your soap is done curing it will have about 15% of its original water content remaining.

Default Values

Every new soapsheet workbook will have a default alkali of NaOH (bar soap), a lye discount of 0%, bar size of 4 ounces, and scale factor of 1. Any of these may be changed. To save your changes for future workbooks, see "Changing the template" below.

Changing the Template

Here's how to change the template:

1) Create a new soapsheet workbook.

2) Make your changes/additions to SAP Values, bar size, lye discount, and/or scale factor.

3) From the File menu, click Save As.

4) In the 'Save as type' dropdown list box on the 'Save As' dialog, choose 'Template (*.xlt)'. This choice should automatically change the 'Save in' directory to your Templates directory.

5) In the 'File name' box of the 'Save As' dialog enter 'soapsheet' (the original name), or whatever name you would like to use for the new version of the template.

6) If you are replacing the template you started with in step one, you will be prompted whether or not to overwrite the original. Click 'Yes'.

7) You're done.



What the heck is a '.xlt' file?

The .xlt, versus .xls, indicates that it is an Excel spreadsheet _template_, not actually a spreadsheet. Every time you open it, it will create a new workbook in Excel that you will be asked to name when you save (i.e. it's hitting the `New' button to create a new workbook, but instead of being blank, it's got all of this stuff from the template in it already). Normally templates are kept in the Templates directory under the directory where Microsoft Office was installed. For me, under WindowsNT 4.0, that defaults to c:\program files\microsoft office\templates. Once the template is installed in the templates directory, picking File>New off of Excel's menu will pop up a dialog for choosing a template or wizard for the new workbook. Just pick 'soapsheet.xlt' from the General tab, and you are good to go.

Why is the total effective lye discount greater than my lye discount, even though I specified no superfatting oils?

Why is the total effective lye discount different for the scaled version of my recipe?

The answer to these two questions has to do with the fact that lye amounts are rounded down to the nearest tenth of an ounce, as detailed in "Lye calculation and rounding" above. To answer the first question, by way of example: if you specify a lye discount of 5%, which puts the lye amount at, for example, 7.39 ounces, the number 7.39 will be rounded down to 7.3, giving you a total effective lye discount of almost 6.2%. That's a 1.2% higher discount, all because you lost .09 ounces of lye to rounding. Are you with me so far? Now on to question two... The reason why the total effective lye discount may be a different value on the scaled version worksheet than the recipe worksheet is that the amount being rounded off of the lye amount will almost certainly change, and it will be a different proportion to the lye amount than in the unscaled version. For example: say I have a recipe with a 5% lye discount, which puts the lye amount at 8.66 ounces, which rounds down to 8.6, giving me a total effective lye discount of around 5.7%. Then I go to the scaled version worksheet and double the batch size. Now my 5% discount puts the lye amount at 17.32 ounces, which rounds down to 17.3, giving me a total effective lye discount of only about 5.2%. This effect can work the opposite way too, with the total effective lye discount going up when you change the batch size. It is even more pronounced when you scale down to smaller batch sizes, because even a small amount rounded off is a proportionately larger change than in a large batch. I hope that makes sense to everyone. There's no way around this without taking a smaller lye discount than what you originally entered.

This page last updated on 8 October 2002.