# Lye Discounting

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#### Tanzi

##### New Member
Hi, I hope this isn't too stupid a question. I'm fairly new to soapmaking and have had a few successes and one disaster
I have a number of beautiful soapmaking books and and also am beginning to use Soapmaker 3.
I understand the basics of lye discounting/superfatting and between checking and converting the recipes from imperial to metric and entering them into soapmaker I end up with differing quantities of lye/water.

I did have Soapmaker set to a default of 6% lye discounting, but even when I change this to no discounting (assuming the recipe books would already have discounting applied).

I end up with 3 different calculations and I just don't know which to use. (see attached)

Would recipe books already have lye discounting applied? How can I tell if a recipe is already discounted and by what %? I assumed this would be noted in the books themselves, but have scoured them and found nothing (at least for the ones I want to make this weekend)

I'm probably overthinking it, I tend to do that.... but thought I'd throw this out there and see if anyone else's brain has gotten stuck on this

View attachment Lye Comparison.pdf

#### topofmurrayhill

Welcome to the forum.

The differences in the amount of caustic aren't so large. Slight differences in the lye discount and the oil SAP values used in the calculation would account for the discrepancies. I suggest you use the SAP values in your own calculator and whatever lye discount you want to use. With variations in the oils and such, there are no absolute correct numbers anyway. It's all estimation combined with personal preference for things like lye discounting. 5 or 6% should be just fine to start.

We don't tend to think of water as part of the recipe, since it comes through the process unchanged. Water amount is more a matter of technique. We usually talk in terms of lye concentration, meaning caustic divided by (caustic + water). I suppose Soapmaker includes at least the usual choice of (a) water as % of oils, or (b) lye concentration. If you set it to the latter you'll be speaking our language.

You can do it around 28 to 30% concentration like the numbers you listed, which is generally called full water. It gets you slowest trace, highest tendency to gel, more shrinkage, and a longer drying time. Pluses and minuses. Most soapers eventually settle on a concentration around 33%, which is a good compromise between low and high water. This slightly higher concentration (less water) compared to the numbers you were looking at shortens time in the mold and drying time after cutting, as well is decreasing the chances of oil and lye separating in the mold.

So the discrepancies in water, though they look more significant, in some ways matter less because the results are eventually about the same. You may want to start by setting your lye concentration to 30% and later you can increase it if you like.

#### penelopejane

##### Well-Known Member
I think you have to write the recipe from the book into your soap calc and fiddle with the % lye concentration until the amount of water and lye equals the amount in the recipe.
For your peace of mind if you make a recipe at 0% SF there is still a bit of safety built in because the lye you buy is not 100%. This means that even if you use 0% SF there will not be any lye left after saponification.

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#### Tanzi

##### New Member
Thank you!

Thank you both for your answers, it's nice to have someone to double check things with and that doesn't roll their eyes at me when I'm trying to work something through.

Tomorrow I attempt Calendula Soap and Honey and Oat Soap.:grin: