Wheatgerm oil - fine on skin raw but saponified it BURNS

[bristles]

Wheat germ oil is used in a lot of cosmetics for its moisturising and high vitamin E values etc. Its not used in soaps much however so I recently did some tests. It's fine in my skin and my housemates skin as an oil but once saponified it really burns and irritates the skin. My housemate and my partner experienced the same burning so I ruled out that we would all have some weird allergy. Can anyone explain this or has anyone experienced similar?

I should clarify I tried a few recipes around the 10% mark and noticed a mild irritation (the superfat was 8%). Then I tried a 100% wheatgerm oil soap just to be sure it was the wheatgerm oil being the irritant and yes. It's a torture device. The wheatgerm oil I used is unrefined and from a reputable seller. So any idea what's happening? ( In case anyone asks there wasn't any excess lye or anything like that. Actually now that I come to think it, is wheatgerm oil so high in unsaponifables that it leaves a lot of free lye left in?. I calculated my recipes on soapee.com)

EDIT: I looked up the SAP value of the oil I bought and it is 194.
Soapee says sap values for wheatgerm oil is KOH: 0.183 and NaOH 0.13, what this this mean

 

[earlene]

Most of what I read for using Wheat germ oil in soap is to use it at 5-10 or even 15% , that it is conditioning, an antioxidant, that it provides a nice golden color to soap and it has a sap value of 0.13 for NaOH. But so far I haven't found anything about it causing irritation, nor about having high amounts of unsaponifiables. There are several threads here at SMF in which its use has been discussed, but not to any great length.

But this thread seems to have a bit more info than the others I found: https://www.soapmakingforum.com/threads/wheat-germ-oil.19644/

And I found this post, but no report on how the soap was after cure: http://curious-soapmaker.com/soap-with-wheat-germ-oil.html

Here it is suggested it can be used up to 15%: https://www.thesprucecrafts.com/qualities-of-soap-making-oils-517120

At the Sage, there is a blog post about a soap with 68% wheat germ oil: https://blog.thesage.com/2011/01/18/coconut-wheat-germ-oil-soap-test-2/

 

[DeeAnna]

The saponification value tells you the grams of alkali needed to saponify 1 gram of fat. The grams of alkali depend on the actual alkali you use. If you use KOH (potassium hydroxide), you need 0.183 grams of KOH to saponify 1 gram of wheatgerm oil. If you use NaOH (sodium hydroxide), you need 0.130 grams of NaOH to saponify 1 gram of the fat.

In scientific literature and in the commercial soap making world, the saponification value is always for KOH.

In the handcrafted soap making world, you need to ask whether it's the KOH sap value or the NaOH sap value. There's no agreed-upon convention, so you have to ask or be told.

Before you assume the irritation is caused by wheatgerm oil in general, I'd try wheatgerm from another seller.

 

[bristles]

The saponification value tells you the grams of alkali needed to saponify 1 gram of fat. The grams of alkali depend on the actual alkali you use. If you use KOH (potassium hydroxide), you need 0.183 grams of KOH to saponify 1 gram of wheatgerm oil. If you use NaOH (sodium hydroxide), you need 0.130 grams of NaOH to saponify 1 gram of the fat.

In scientific literature and in the commercial soap making world, the saponification value is always for KOH.

In the handcrafted soap making world, you need to ask whether it's the KOH sap value or the NaOH sap value. There's no agreed-upon convention, so you have to ask or be told.

Before you assume the irritation is caused by wheatgerm oil in general, I'd try wheatgerm from another seller.

I will try another wheat germ oil from a different seller and this time a refined one, not a virgin one.
It feels like this wheatgerm oil hasnt taken up any lye hence the burning on my face feels like excess lye, strange

 

[DeeAnna]

First you assured us --
"...In case anyone asks there wasn't any excess lye or anything like that...."
And now you say --
"...It feels like this wheatgerm oil hasnt taken up any lye hence the burning on my face feels like excess lye..."

I'm feeling confused. Pick one of the soaps and please tell us this information --

How old is this soap?

Have you zap tested it?

If so, is it zap free?