Water and Lye Discounts

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pink-north

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This may seem like a stupid question, but could someone please explain to me (in laymans terms) the meaning of water and lye discounts? I would really like to have a better understanding of it.

Thanks :)
 
To my understanding:
Lye discount is a reduction in the amount of lye used, which basically means the soap will be less harsh but will take a lot longer to harden up.

Water discount means less water which is then made up for with more lye, which will give you a harder bar faster, but also a harsher soap.
 
lye discount/ superfat (short = SF)

Each oil is a bit different in composition and therefore the saponification value will vary. To make sure your soap:
1) won't end up lye heavy
2) will be more gentle on the skin
you need a lye discount, which we often call superfat.

http://en.wikipedia.org/wiki/Saponification_value

When you have a recipe that is known to shrink while curing or that stays soft for a long time (such as a 100% olive oil, or castille soap) you can use less water.

Over at www.soapcalc.net you will be able to make your own recipes and adjust your superfat and water to your personal preferences.

@phpworm; maybe I don't understand your reply correctly, but with a water discount, the amount of NaOh stays the same; it's just that by using less water the lye-water solution gets stronger.
 
Yea, I didn't get that either.

When you discount water, you don't make up for the lower amount of water with lye. You simply use less water.

This creates a lye solution with a higher CONCENTRATION but does not impact the amount of lye.

Discounting water does not result in a harsher bar. a wetter one, so to speak.
 
So let me see if I get this right. If I'm looking for a hard bar of soap that's also easy on the skin I would discount my lye but not my water or discount them both, let's say 5% (or whatever amount I need)?
 
My mistake, I thought less water meant more lye. I guess I never paid attention to the calc numbers, since it does all that for you automatically anyway.

I personally never discount lye more than 8%. If I want a harder bar of soap or expect it to turn out soft, then I just discount the water.
 

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