Lye Discount vs Superfat (practical application)

[Absinthe]

If am understanding this correctly, these 2 don't really mean the same thing exactly.

In a lye discount, you calculate everything for a given recipe, and then use less lye.

In a superfat, you calculate everything for a given recipe, and then use more fat.

However, both terms seem to be used interchangeably because of how they are applied. When I read about "superfatting" as opposed to lye discounts, there are discussions as to which fats should be used for the superfatting. This suggests to me that when doing this, your intention is to have a specific fat remain unsaponified, as opposed to some of each on the combined fats.

In order to insure that the maximum percentage of a particular fat remains unsaponified, while all the rest of the recipe gets saponified as much as possible when is the best time to add the superfatting fat?

Would it even be best to simply make the recipe ignoring the superfatting fat, and allowing no lye discount at all. Then calculate the weight to add based on the original recipe. (e.g. 1000 g recipe, add 100 g of the superfat fat for 10% superfat)

In theory, at some point, light/medium/heavy trace, gel stage or something all the lye is committed to saponification of the other oils and it would be safe to add the superfatting fat with the expectation that it would not, for the most part, get saponified, thus preserving its specific attributes.

Any experiences with this?

When lye discounting instead, and all the oils are mixed together, when the lye water is added, will the lye react more quickly with one type of acid over another, (assuming perhaps something based on the chain length of the particular fat) ? If this is the case, then whichever attributes cause the fat to get saponified first thus using up the lye, will cause a particular one (with the opposite attributes) to be the "superfat".

I am imagining lye as if it were fire in an enclosed box. And the fats as though they were pieces of combustible material. Some will be like sawdust, others like crumples paper, some like chunks of wood and so forth. So in this metaphor, the fire consumes the more easily consumables first, and when it burns out (uses up the O2) it stops. What is left over in this case are the larger chunks that didn't get fully ignited, but all the sawdust and paper will have been consumed.

Is this reality? Anyone have experience with this? Does this suggest a strategy for which fats to combine so that a particular one automatically becomes the superfat when lye discounting?

 

[IrishLass]

I'm no chemist, but I calculate my superfat right up front (as opposed to adding a particular fat later) based on the experiments of those who have tested their soaps in an actual lab. There is a soaper on another forum that has actually done so and I've based my decision to account for my superfat % up front due to her results, instead of taking a lye discount and adding a fat later..

Her results, based on several, varying batches of soap, consistantly showed that at trace (when most people are apt to add a specific superfatting oil), only a mere 10% to 15% of the oils/fats have actually become saponified yet. That leaves a whopping 85% to 90% of free lye on the loose to gobble up whatever fatty acids are in the pot, making the fatty acids in your superfat fair game along with all the other fatty acids that were added earlier. The conclusion was that it is only wishful thinking for one to believe that the oil/fat that was added at trace will remain unsaponified.

The way I understand it, active lye is an equal opportunity gobbler and doesn't differentiate between a fat you added up front from one you added later. It sees the fats purely in terms of their fatty acid makeup, and if the lye is active and sees a fatty acid it can eat, it's fair game with all the others that were added up front. There's no way of controlling it, especially with so much still-active lye on the loose.

The only way I know of controlling what oil/fat remains unsaponified is to use the HP method, adding the superfatting oil/fat to the soap batter after the cook when the soap doesn't zap anymore.


IrishLass

 

[carebear]

Yes, and no - they don't mean exactly the same thing, but the final result is the same.

It doesn't matter whether you add the "superfat" oil at the beginning (more easily done by simply discounting the lye) or at trace because

1- the vast majority of saponification is still to take place and
2 - soap is not static and the fatty acids do a little dance swapping in and out of the salts so that even if you superfat an HP soap you may not end up with that particular fat still intact.

Superfatting, IMO, is simply setting yourself up for mistakes. Particularly in CP.

 

[gekko62]

Also,I have heard the theory(not 100% it's been lab tested) that there may be fatty acids that lye finds easier to eat. Like if it's knawing on an old chop bone and suddenly a tender juicy piece of eye fillet drops in,then it'll leave the old bone and chow down on the steak.So adding an oil later in the process would be a waste of time anyway.