Monday, August 4, 2014

Understanding Superfat

Superfat is literally extra fat that you have in your soap recipe that does not become soap.  It is NOT saponified because there is not enough lye in the recipe to make ALL the oils turn into soap.  The oil is kind of floating in between the soap molecules, so when you use the soap, not only does it clean, but it also deposits a thin layer of fresh oil on your skin.

This is a great cartoon that helps explain superfat & what is going on in the bowl/pot while you are making soap.
Bunnies & Wolves

In a Cold Process (CP) recipe the lye is not finished working when you mold the soap.  Unfortunately, that means that the lye gets to pick which oils it will saponify.  Maybe you want to add a rather expensive luxury oil as a superfat.  There is no guarantee in CP that the oil YOU want to make the superfat will wind up as the superfat.

In Hot Process (HP), the lye is finished working, as a result of using heat to accelerate the reaction, when the soap is put in the mold.  You can test the pH of the soap or do a "zap test" to make sure the soap is "done", completely cooked, & no lye remains.  The zap test is where you touch the tip of your tongue to a small bit of cooled soap.  If it "zaps" you like a battery would, then there is still active lye.  If it just tastes like soap, then it's done.  I f you DO get a zap, make sure you rinse out your mouth with some water & spit.  When the HP soap is done, there is no further reaction taking place between the alkaline lye and the acids in the oils.  The soap has finished the saponification process.  Now, if you add your superfats, they will not be touched by the lye because there is no lye, anymore.  The oils & lye have all been turned into soap.  You can add your superfat & be assured that it will remain intact as your superfat.  Whatever oil(s) you chose to add as your superfat you can believe that it will remain your superfat.  In other words, if you make a soap out of lard, but want apricot oil as a superfat, if you add the apricot oil after the cook it will remain the superfat.  There will be no sneaky action from the lye to turn your apricot oil into soap & give you back some lard as superfat.

Most soap calculators have a space for you to put in the superfat % you want.  This is based on the weight of the oils in your recipe.  In CP soap if you are using 16 oz oils and set your superfat % at 5%, the calculator will deduct 5% (0.8 oz) of oils from your recipe which will not be saponified.  You can see the difference in the lye amount if you run the recipe through the calc at 0% superfat, then change it to 5% superfat.  Soapmakers used to believe that if you added the superfat at trace in CP then there was less chance that the lye would saponify it.  Unfortunately, this is not true.  The lye takes the easiest oils it can grab onto for the chemical reaction.  Whatever the most difficult oils to saponify in your recipe are, will most likely be your superfat.  If you are making CP soap just let the calculator figure your superfat.  Put the percentage you want in the clculator & follow the recipe it gives you.
If, however, you are making an HP batch, you will probably want to calculate the superfat on your own.  Using the same example of a 16 oz batch.  There IS a way to calculate this so you wind up with 16 oz oils total, but it is not very easy & may make your brain hurt.  Here is an easy & accurate way to do it.  Remember I said that superfat was a percentage of the oil weight.

16 oz X 0.05 (also known as 5% or 5 hundredths) = 0.8 oz

Ok, so is it really a big deal?  You wind up with 16.8 oz, not 16 oz exactly.  So if your mold only holds 16 oz, put the 0.8 oz in a yogurt cup :D

I am not trying to imply in this article that 5% superfat is ideal.  It depends on YOUR skin or hair.  I happen to like 3% superfat in my shampoo bars, (recipe in link, below)
Liz's Shampoo Bars

I have older dry skin & prefer 8-12% superfat in my body bars.  Coconut oil makes a nice soap but is VERY cleansing.  That means it strips all the oil off your skin.  I don't like it, but a lot of people find it a fabulous soap.  It is usually superfatted at 20-25% for body soap because of the high cleansing of the bar.  Coconut oil makes a GREAT laundry soap.  You don't want extra oil (superfat) on the clothes you are washing so it should be made at 0 or 1% superfat.  1% is just to be safe & make sure there is a pinch of extra oil for the lye to saponify.  A safety net, so you don't have any lye left over.


21 comments:

  1. Hi Liz. I've been trying to understand the superfat thing for HP for awhile. I use Brambleberrys lye calc and just set the superfat to 5% or 6% and follow the recipe. Please tell me how to add my superfat after the cook. I read your article, but I just don't understand how to calculate it. Do I set the superfat at 0%, then follow the recipe amounts for lye and liquid? How do I know how much of my superfat oil to add? Is it figured into the original recipe oils? Sorry, I am just not getting it. But I really want to!

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    1. Hi Anna, For HP, run your recipe thru the lye calc at 0% superfat. You will have your oils, lye & water amounts for your batter. Now comes the part you are keeping secret from the lye calc, the superfat. Figure the amount in your head, with paper & pencil or a calculator. Take the oil amount in your recipe, let's say it is 16 oz. You want 6% superfat. 6% is also known as 0.06 or 6 hundredths. Multiply your oil weight (16 oz) by the superfat percent you desire (0.06) or 16 X 0.06 = 0.96 that would be 0.96 oz for a 6% superfat for a 16 oz batch. Hope that makes it clearer.

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    2. Liz, thank you! Yes! I get it now. The light bulb finally went on. Very clear info, thanks for your time and help. :)

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  3. Edit on my comment:
    Ok, Liz, I've read this thing about 10 times, and I'm still confused. Let me say what I'm thinking it says and you tell me if I got this right. Say I want to superfat with almond, avocado and apricot oils. Do I leave them out of the soapcalc, and calc the rest of my oils at 0%, then figure out the weight of those oils and superfat my % of the 3 oils?
    ex: say my total oil weight oils without sf is 24 oz, Would I take 24 x .10 and that would make my total weight of sf be 2.4 oz, or if I wanted equal portions of the 3 oils, .8 oz each?

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    1. Exactly, donnebonn! You described it perfectly!

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    2. What's the .10 for. I am so confused

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  4. Thanks, Liz, you're awesome. Thanks for this blog.

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  5. Hi Liz, Christine Reid here. We discussed SF and that I didn't 'get it' on the FB page yesterday? Or the day before. I decided to come back and give it a try. I now get it!
    My only problem is I would love an example in grams! I am also assumimg, it doesn't matter what the sap values of the SF(s) are so long as you stick to the percentage? In fact, now I have just thought of another question! If someone's superfat is very high does the method work the same? Will also post this on the HP page on FB.

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  6. Dear Liz Thank Thank youuuu for share!! God Bless you!!

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  7. Great BLOG Liz and thanks for the Bunnie/Wolf link!

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  8. Oh thank God for this article!

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  9. Thank you. Just the info I was looking for.
    I do have one question: I plan on superfatting at 5% after the HP process. But, should I take a 1-3% lye discount to make sure that all the lye is saponified? It is my understanding that the SAP values are averages, so maybe it is important to do some lye discount even if you are superfatting at the end of the HP process.
    What do you think?

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    1. A lot of experienced soapmakers use a small percent of their superfat amount (lye discount) in their main recipe as a safety net for just the reason you are stating. I don't, but there is no danger of me cooking the no superfat soap to death waiting for the lye to "cook out". Lye doesn't cook out, it needs more oil to react with. The superfat I add after cook takes care of any residual lye from variable SAPs. Just remember that ALL superfat counts, so if you have 3% superfat in your recipe, then you only will be able to add 2% after cook if your goal is 5% total.

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  10. Great article! Oh I think your link to the bunnies has been corrupted.

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  12. I'm so glad I found this site. I am also a newbie at soaping so this was a great help.The problem that I'm getting is lye in my finished soap. I add my oils and butters, do a 5% SF in the lye calc then also add 1.50oz of cream to the batter with Kaolin clay before adding the lye/water. When I test my soap after 3 days it shows up being lye heavy.Can someone please help?

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