Understanding what oils accelerate trace and at what levels

[Clarice]

Hi - as a new soaper, I am still getting my sea legs (lather legs?)

There was a great discussion in another forum in which a member asked about trace. @lsg advised that the recipe about which the question was posed had a high level of unsaturated fatty acids, which tends to accelerate trace.

I asked a follow-up question and @lsg advised me this was a good Q for its OWN thread

https://www.soapmakingforum.com/threads/help-with-accelerated-trace.74384/#post-758765

My Questions:

What I am trying to wrap my head around is which oils tend to accelerate trace, and at what percentages of use this tends to happen.

Because I am still familiarizing myself with the fatty acids, I also immediately went to Wikipedia to learn which of the fatty acids are "unsaturated". Here is that link

https://en.wikipedia.org/wiki/List_of_unsaturated_fatty_acids

At what level or percentage in a recipe do "oils that accelerate trace" kick in?

Is there a rule of thumb, i.e., keep XYZ fatty acids below X% to achieve a slow trace so that you can do more intricate patterns?

Other advice?

Thank you so very much Gurus of Soap!


C (and all the other beginners who will benefit from your knowledge!)

 

[earlene]

That's a good question about at what percentage before the acceleration kicks in. I am not going to be able to answer this definitively for each oil or any for that matter, but from my own experience, I can attest to the fact that at 50% pomace olive when mixed with regular olive oil accelerates fast enough that I don't even use a stick blender to reach trace in only about 3-5 minutes of hand stirring.

 

[Clarice]

@earlene may I ask why you use half half pomace and regular? (and wow )

 

[lsg]

Here is a way to sort oils by their fatty acids and sap rate: http://soapcalc.net/calc/oillist.asp

 

[Clarice]

Thank you @lsg , and am I understanding correctly that on a comparative basis:

oils with higher levels of the unsaturated fatty acids (oleic, linoleic, linolenic and ricinoleic) will trace faster than those with saturated fatty acids and / or lower levels of unsaturated?

Penny dropping slowly

 

[earlene]

@earlene may I ask why you use half half pomace and regular? (and wow )

I was making Castile soap and used half and half to speed up trace.

 

[dixiedragon]

Thank you @lsg , and am I understanding correctly that on a comparative basis:

oils with higher levels of the unsaturated fatty acids (oleic, linoleic, linolenic and ricinoleic) will trace faster than those with saturated fatty acids and / or lower levels of unsaturated?

Penny dropping slowly

The opposite, I think. Oils with higher levels of palmitic, stearic and myristic acid. The hardness number at the end of the calculator can be a good indicator of this.

For example:
Lard
(pork fat)
Oleic 44-46%
Palmitic 26-28%
Stearic 13-14%
Linoleic 6-10%
Myristic 1-2%

VS

Beef tallow
Oleic 37-43%
Palmitic 24-32%
Stearic 19-25%
Myristic 3-6%
Linoleic 2-3%

Lard makes a slower-tracing but ultimately hard bar, vs tallow (or palm) which tend to trace face and make a hard (perhaps harder than lard) bar.

 

[earlene]

Olive oil is very high in oleic acid and takes forever to trace if not pomace OO. So, no, I would not expect high Oleic oils to trace fast at all.

An experiment you could try:

Make a small batch of 100% single oil soap using a high Oleic oil, such as olive oil (non-pomace OO) or canola oil. Hand stir only, and record how long it takes to trace. Make the same recipe using a stick blender and record the time to trace.

Then make a single oil soap using a known fast-tracing oil (such as castor or coconut) and do it the same way; hand stir only for one batch and then use a SB for another batch, recording time to trace in each situation.

 

[Lakee]

Here is a way to sort oils by their fatty acids and sap rate: http://soapcalc.net/calc/oillist.asp

Thanks so much for that link. Very helpful.

 

[SaltedFig]

Triglyceride
The oils and fats that we make soap from are often in the form of triglycerides.
A triglyceride is 3 fatty acids attached to a glycerol backbone.

Saponification
Saponification of triglycerides occurs in two steps.
The first step is to break the fatty acid from the glycerol backbone, and
The second step is where the soap is formed (and becomes sodium soap, if we have used NaOH).

Saturated vs Unsaturated
Our oils and fats are saturated or unsaturated
The fatty acids that are saturated have straight carbon tails, and the unsaturated oils and fats have one or more kinks in the links of carbon.
Trivia: Fats and oils that have been hydrogenated have had these kinks chemically straightened out

Saponification speed
The short, straight carbon chain fatty acids (aka, the saturated fats with a smaller number of carbon atoms in their tail) are the quickest to saponify.
The longer, kinkier fatty acids (aka, the unsaturated fats with the larger number of carbon atoms in their tail) are the slowest to saponify.

Lipid numbers
Knowing this, have another look at the link lsg provided (http://soapcalc.net/calc/oillist.asp)

If you look at the first one (Lauric), you'll see that it is Sat (Saturated) and has the numbers 12:0 next to it.
The first number (12) tells you how many carbon atoms are joined together in the carbon chain
The second number (zero) tells you that there are no double bonds in that chain.

Trivia: Single bonds (between the carbon atoms) make a straight join, double bonds pull the chain off to one side (and cause the carbon chain to kink)

So now you can interpret the lipid numbers (C : D, or carbon to double bond ratio) for yourself, to work out how long the carbon chain is, and how many bends it has. By knowing that a saturated fat is straight, you can also start to distinguish between saturated fats and unsaturated fats, just by looking at the numbers!

Lauric acid 12:0, has 12 carbon atoms and no double bonds (it is straight and saturated)
Myristic acid has 14:0, has 14 carbon atoms in its chain and it is straight (saturated)
Palmitic acid is 16:0, so a saturated fatty acid with 16 carbon atoms
Stearic acid is 18:0, so a saturated fatty acid with 18 carbon atoms

Ricinoleic is 18:1, so it has 18 carbon atoms in a chain, with one double bond (which makes it monounsaturated)
Oleic is 18:1, so it also has 18 carbon atoms in a monounsaturated shape
Linoleic is 18:2, so it has 18 carbon atoms and a couple of double bonds (it has a polyunsaturated shape)
Linolenic is 18:3, and it's very kinky

Why is all of that important?

Because, as a general rule, the shorter and straighter the carbon chain, the faster the fat will saponify

Three examples:
Coconut has a high amount of Lauric acid in it's profile. Lauric acid is only 12 carbon atoms long and is a saturated (straight) fatty acid.
Just on the numbers, we would expect coconut oil to saponify quickly.

Olive oil has a high amount of Oleic acid in it's profile. Oleic acid has 18 carbon atoms and is monounsaturated, so we would expect that this would take a lot longer to saponify, based on the larger size and bent shape of this fatty acid.

Cocoa butter contains more Stearic acid, which is of a similar size to Oleic, at 18 carbon atoms, but Stearic acid is a saturated fatty acid and will saponify more easily than Oleic acid, so Cocoa butter will trace quicker than Olive oil.

Pure fatty acids:
An exception to this would be where you are saponifying fatty acids directly - soaping with fatty acids directly is fast!
Fatty acids are already free of any glycerol backbone.
This is why Stearic acid (as an example) is so very quick to turn to soap - half of the job has already been done ahead of time

Some extra things to looks at:
This wiki page has some cute pictures of different shapes fatty acids can come in:
https://en.wikipedia.org/wiki/Fatty_acid

This is a longer list of saturated fatty acids, and includes the lipid numbers (C : D ratios), common names and links to even more detail!
https://en.wikipedia.org/wiki/List_of_saturated_fatty_acids

This is a longer list of unsaturated fatty acids, and the oils and fats they naturally occur in:
https://en.wikipedia.org/wiki/List_of_unsaturated_fatty_acids

Apologies for the very long answer - I hope the story behind the numbers has given you a little insight into why some fats and oils come to trace (and turn to soap) quicker than others

 

[Clarice]

@SaltedFig

Oh my goodness. Thank you SO MUCH for this very detailed answer which I will read and re-read so that I can absorb all the information

It is SO GENEROUS of you to take the time to answer in such a detailed manner, and I am so very grateful!

I am blown away! Thank you!

 

[Hils67]

Triglyceride
The oils and fats that we make soap from are often in the form of triglycerides.
A triglyceride is 3 fatty acids attached to a glycerol backbone.

Saponification
Saponification of triglycerides occurs in two steps.
The first step is to break the fatty acid from the glycerol backbone, and
The second step is where the soap is formed (and becomes sodium soap, if we have used NaOH).

Saturated vs Unsaturated
Our oils and fats are saturated or unsaturated
The fatty acids that are saturated have straight carbon tails, and the unsaturated oils and fats have one or more kinks in the links of carbon.
Trivia: Fats and oils that have been hydrogenated have had these kinks chemically straightened out

Saponification speed
The short, straight carbon chain fatty acids (aka, the saturated fats with a smaller number of carbon atoms in their tail) are the quickest to saponify.
The longer, kinkier fatty acids (aka, the unsaturated fats with the larger number of carbon atoms in their tail) are the slowest to saponify.

Lipid numbers
Knowing this, have another look at the link lsg provided (http://soapcalc.net/calc/oillist.asp)
View attachment 37705
If you look at the first one (Lauric), you'll see that it is Sat (Saturated) and has the numbers 12:0 next to it.
The first number (12) tells you how many carbon atoms are joined together in the carbon chain
The second number (zero) tells you that there are no double bonds in that chain.

Trivia: Single bonds (between the carbon atoms) make a straight join, double bonds pull the chain off to one side (and cause the carbon chain to kink)

So now you can interpret the lipid numbers (C : D, or carbon to double bond ratio) for yourself, to work out how long the carbon chain is, and how many bends it has. By knowing that a saturated fat is straight, you can also start to distinguish between saturated fats and unsaturated fats, just by looking at the numbers!

Lauric acid 12:0, has 12 carbon atoms and no double bonds (it is straight and saturated)
Myristic acid has 14:0, has 14 carbon atoms in its chain and it is straight (saturated)
Palmitic acid is 16:0, so a saturated fatty acid with 16 carbon atoms
Stearic acid is 18:0, so a saturated fatty acid with 18 carbon atoms

Ricinoleic is 18:1, so it has 18 carbon atoms in a chain, with one double bond (which makes it monounsaturated)
Oleic is 18:1, so it also has 18 carbon atoms in a monounsaturated shape
Linoleic is 18:2, so it has 18 carbon atoms and a couple of double bonds (it has a polyunsaturated shape)
Linolenic is 18:3, and it's very kinky

Why is all of that important?

Because, as a general rule, the shorter and straighter the carbon chain, the faster the fat will saponify

Three examples:
Coconut has a high amount of Lauric acid in it's profile. Lauric acid is only 12 carbon atoms long and is a saturated (straight) fatty acid.
Just on the numbers, we would expect coconut oil to saponify quickly.

Olive oil has a high amount of Oleic acid in it's profile. Oleic acid has 18 carbon atoms and is monounsaturated, so we would expect that this would take a lot longer to saponify, based on the larger size and bent shape of this fatty acid.

Cocoa butter contains more Stearic acid, which is of a similar size to Oleic, at 18 carbon atoms, but Stearic acid is a saturated fatty acid and will saponify more easily than Oleic acid, so Cocoa butter will trace quicker than Olive oil.

Pure fatty acids:
An exception to this would be where you are saponifying fatty acids directly - soaping with fatty acids directly is fast!
Fatty acids are already free of any glycerol backbone.
This is why Stearic acid (as an example) is so very quick to turn to soap - half of the job has already been done ahead of time

Some extra things to looks at:
This wiki page has some cute pictures of different shapes fatty acids can come in:
https://en.wikipedia.org/wiki/Fatty_acid

This is a longer list of saturated fatty acids, and includes the lipid numbers (C : D ratios), common names and links to even more detail!
https://en.wikipedia.org/wiki/List_of_saturated_fatty_acids

This is a longer list of unsaturated fatty acids, and the oils and fats they naturally occur in:
https://en.wikipedia.org/wiki/List_of_unsaturated_fatty_acids

Apologies for the very long answer - I hope the story behind the numbers has given you a little insight into why some fats and oils come to trace (and turn to soap) quicker than others

This is a fantastic explanation and another reason why I’m totally addicted to my soaping journey. It’s not just making soap it’s learning the science behind it. Thank you so much for sharing

 

[SaltedFig]

@SaltedFig

Oh my goodness. Thank you SO MUCH for this very detailed answer which I will read and re-read so that I can absorb all the information

It is SO GENEROUS of you to take the time to answer in such a detailed manner, and I am so very grateful!

I am blown away! Thank you!

You are most welcome Clarice

@Hils67 Thank you for your lovely words
"This is a fantastic explanation and another reason why I’m totally addicted to my soaping journey. It’s not just making soap it’s learning the science behind it. Thank you so much for sharing"

I can say with some confidence that the addiction never goes away
(Now is a very exciting time to be a soaper!)

 

[Sunibee]

Thank you @lsg , and am I understanding correctly that on a comparative basis:

oils with higher levels of the unsaturated fatty acids (oleic, linoleic, linolenic and ricinoleic) will trace faster than those with saturated fatty acids and / or lower levels of unsaturated?

Penny dropping slowly

My understanding is that it is the opposite higher unsaturated fats.. more slow to trace
. Hard oils more saturated ..more quick to trace. This is my understanding

 

[AliOop]

My understanding is that it is the opposite higher unsaturated fats.. more slow to trace
. Hard oils more saturated ..more quick to trace. This is my understanding

This is a fairly old post, but I want to remark that this statement is not correct.

Lard has a significant percentage of saturated fat, and it is one of the slowest to trace.

Tallow is also high saturated and slow to trace. It isn't quite as slow to trace as lard, but it is definitely slower than castor or RBO, both of which are primarily unsaturated, and both of which speed up trace for me, especially the castor.

 

[Rsapienza]

IME, trace has way more to do with how much my SB is used than which oils I’ve used.

 

[Mobjack Bay]

The “secret” behind the behavior of lard may have to do with the structure of the triglycerides. Bakers blog about lard having a large “fat crystal” as an explanation for why it performs so well for baking pastry. The most reasonable explanation that I could find for lard being slow to trace is that more of the stearic and palmitic fatty acids are sandwiched between two oleics when compared with tallow or palm. It seems reasonable, but I would love to have a chemist’s perspective.

eta: if the structure of the triglyceride matters, it’s also an explanation for why lard replacements based on fatty acid profiles do not produce lard equivalents when it comes to trace behavior.