Masterbatching lye- how to?

[Yooper]

I'm helping out with the new soap calculator here for SMF, and the question of adding masterbatching lye to it came up.

Since I have never done it (can't have lye solution hanging around), I need some advice on how to go about mixing it, and the amounts, and then how to use it in a soap recipe. Can anybody explain it to me, so that I can understand what benefit it could be? I know for large batches it could save time, but other than that, is there a benefit? And how exactly is it used in the soap recipe then?

 

[SaltedFig]

I masterbatch my lye so that I have some to hand when I want to make soap (it's always ready and always cool enough).

The ratio is really easy - half (by weight) water and half hydroxide.

That's enough to fully dissolve the hydroxide (NaOH or KOH), is easy on the maths (it's a 1:1, or 50% lye concentration) solution.

Masterbatch lye is still safe to use in soapmaking (although it can have an unusual effect on the speed of saponification at this concentration), and it doesn't react with the air nearly so badly as "solid" hydroxide (solid hydroxide is ridiculously hygroscopic).

My very most favourite reason to masterbatch? I can add another liquid without worrying about how it's going to react when the lye hydroxide goes in. So no fatty lumps (for milk type liquids), no overheated coconut water, no superbubbling for beer ... I can add the alternative liquid to my oils, independently of the masterbatch lye

And the math for the extra liquid? Add the lye hydroxide weight again (as the extra liquid) and you get a 2:1 Liquid:Hydroxide ratio (roughly 33% lye concentration), which is terrific for just about any recipe you can think of (although other concentrations are possible, it makes double-checking and spotting errors quite straightforward)

The big (and it's huge) drawback for masterbatching is safety. In liquid form, lye is at it's most dangerous (extremely dangerous). I wouldn't recommend it for anyone that does not have lockable storage for it. Danger warning labels are also necessary (I have stories, not mine, which I will not share, but it must be labelled and locked IMHO).

 

[DeeAnna]

I agree with your advice, @SaltedFig, except I would replace "lye" with "dry alkali" in this phrase -- "And the math for the extra liquid? Add the lye weight again..."

If you gave me this advice as you wrote it, I add an additional weight of water equal to the lye solution ("lye" for short.) I'm nearly certain that's not what you mean -- you really want us to add additional water that is equal to the weight of the dry alkali.

I know we often use "lye" when we mean "dry alkali" as well as when we mean "lye solution." I do it, most everyone does it. Most of the time this is fine because the context makes it clear whether we're talking about the dry NaOH or KOH or the liquid solution made from the dry alkali. In this case, I'm not sure the context is enough.

Example:
A recipe calls for a dry NaOH weight = 100 grams. If you wanted to use a 50% NaOH solution instead, you would measure out twice that weight (200 grams) of 50% NaOH solution to get the correct amount of dry NaOH (100 grams) for the recipe.

If you add an additional amount of water equal to the dry NaOH weight, you would add 100 grams of water. The lye concentration would then be 33%. This is the same as a 2:1 water:lye ratio.

If you add additional water equal to the lye solution, you would add 200 grams of water. Lye concentration: 25%. Water:lye ratio: 3:1.

 

[SaltedFig]

@DeeAnna

Lye is the label that the program is currently using - I debated whether to use hydroxide or lye when writing the math, but decided to use the label (despite it's inaccuracy). I might edit two instances with a strikethrough (one could use either name, but I think, on review, hydroxide might suit better) - that should satisfy our desire to use the correct name and still be clear for the person who is trying to find what field I'm talking about (hopefully!).

Do you think dry alkali? Would there be a circumstance, as makers of handcrafted B&B soap, where we would make soap from anything other than a hydroxide?

I tend towards hydroxide as my choice of word for the dry ingredients, as everyone knows sodium hydroxide and most know potassium hydroxide, in the context of it being the dry ingredient used to make lye, so it's an easy move in the right direction, but I'm open to alternate terminology if it has the right balance of clarity, simplicity and readability (one word, 3 syllables is winning over two words four syllables at the moment)

 

[dixiedragon]

I've looked into masterbatching lye before, but I honestly don't trust myself to do the math right. I have a few pitchers with lids, and what I do is put 1 batch of lye + water in there, stir well, and put the lid on it. I almost always do either 1 log batches or 4 log batches, so I plan out my lye that way.

 

[DeeAnna]

...Lye is the label that the program is currently using....

Yeah, I know. If the context is clear, I don't see that it's a problem to use "lye" to mean the dry alkali or the alkali solution. But any time the context isn't clear, it's good to spell it all out. In the example I gave in my earlier post, would have to ask you what you meant -- solid or liquid? -- if I were following your directions.

"...Do you think dry alkali?..."

Use whatever phrase makes sense to you and your readers.

Or you can define a shorthand term up front and then use it consistently in your explanation, that works too. For example, you could define terms such as these:

"Alkali" means the dry hydroxide, either NaOH or KOH.
"Lye" means a solution of the hydroxide mixed with water.​

Or whatever works for you.

I will even say "lye solution" to mean a liquid alkali mixture. That's redundant, to be honest, but the phrase leaves nothing to the imagination.

"...Would there be a circumstance, as makers of handcrafted B&B soap, where we would make soap from anything other than a hydroxide?..."

People do ask about wood-ash lye, which would be a carbonate mixture. Not often, granted, but it does happen.

 

[TeresaGG]

@DeeAnna
Do you think dry alkali? Would there be a circumstance, as makers of handcrafted B&B soap, where we would make soap from anything other than a hydroxide?

I just read about using ammonium hydroxide for soap making. Here is a link to an article with the mathematics needed.
https://classicbells.com/soap/ammoniumHydroxide.html

Edit- This could be in the dual alkali area because ammonium hydroxide is typically not sold in high enough concentrations to be used as the sole alkali.

 

[DeeAnna]

You're absolutely right, @TeresaGG. I didn't do that because ammonium hydroxide solution isn't used all that much in soap going by what I see on SMF. I decided to present it as a specialty additive something like vinegar rather than a "normal" alkali like NaOH or KOH. But that's definitely a judgement call.

 

[TeresaGG]

You're absolutely right, @TeresaGG. I didn't do that because ammonium hydroxide solution isn't used all that much in soap going by what I see on SMF. I decided to present it as a specialty additive something like vinegar rather than a "normal" alkali like NaOH or KOH. But that's definitely a judgement call.

Yes that sounds like a good place for it.

 

[SaltedFig]

I just read about using ammonium hydroxide for soap making. ...

I think it was @Nanditasr that recently revived the exploration of making ammonia based soaps (over a number of threads).

TeresaGG - this might be a good opportunity to join in the new soap calculator conversation, it should be possible to include ammonia hydroxide as another hydroxide, at this stage of the development

(The SAP calculations are straightforward, from a programming perspective, and the [modifiable] purity could default to 5% (just as KOH defaults to 90%))

 

[SaltedFig]

"...Would there be a circumstance, as makers of handcrafted B&B soap, where we would make soap from anything other than a hydroxide?..."
People do ask about wood-ash lye, which would be a carbonate mixture. Not often, granted, but it does happen.

I wonder how well the carbonate version of wood ash soap sets up (for the serious soapmaker)?
(I don't recall it making much more than goop, but that's going back a very long way, and I was mostly playing at the time ).

The version of wood ash lye an old chemist taught me uses a solution of fired and crushed shell fossils (slaked lime) to convert the carbonate (potash) into hydroxide (caustic potash) ... it takes a while, but isn't particularly difficult.

I reckon wood ash lye (either sort) could be called the original masterbatching

 

[Nanditasr]

I think it was @Nanditasr that recently revived the exploration of making ammonia based soaps (over a number of threads).

TeresaGG - this might be a good opportunity to join in the new soap calculator conversation, it should be possible to include ammonia hydroxide as another hydroxide, at this stage of the development

(The SAP calculations are straightforward, from a programming perspective, and the [modifiable] purity could default to 5% (just as KOH defaults to 90%))

Indeed, I did. However, I don't know how popular it is -- people tend to get a bit scared if they hear "ammoni..."; NaOH or KOH do not have the same effect. I have googled it, but I'm unable to find any documentation to say that NH4OH is any more dangerous than the rest; in fact, its pH is a shade lower than that of the other two alkalis. Of course, pH alone may not determine how "dangerous" something is; it will be great if someone can throw light on this (but maybe on a different thread).

 

[DeeAnna]

...I'm unable to find any documentation to say that NH4OH is any more dangerous than the rest; in fact, its pH is a shade lower than that of the other two alkalis. Of course, pH alone may not determine how "dangerous" something is

Ammonia solution needs to be treated with extra respect because it is highly volatile, unlike KOH or NaOH. Any one of the three can damage your skin and eyes from a splash, but ammonia also evaporates easily out of solution into the air. It is a strong respiratory and eye irritant. If you're using ammonia in soap, it's important to be aware of the potential danger to your eyes and lungs during soap making. Good ventilation is a must.

...The version of wood ash lye an old chemist taught me uses a solution of fired and crushed shell fossils (slaked lime) to convert the carbonate (potash) into hydroxide (caustic potash) ... it takes a while, but isn't particularly difficult....

You can make soap directly from the carbonate lye (or even sodium bicarbonate), but it takes a lot more heat and time than if you can make soap directly with a hydroxide lye. I agree -- reacting wood-ash lye with slaked lime to form a hydroxide lye makes soap making a lot easier.

It's been a long time since carbonate lye from ashes was the norm for soap making -- manufactured sodium carbonate (washing soda) eventually took its place. Washing soda still should be converted to the hydroxide with slaked lime, but the sodium soap made from washing soda is firmer and purer than a wood-ash lye soap, so it was a great improvement in quality. More: https://classicbells.com/soap/woodAshLye.html

 

[SaltedFig]

You can make soap directly from the carbonate lye (or even sodium bicarbonate) ...

No thanks.

The hydroxide form of wood ash lye was an exploration of making from scratch that the old chemist had been taught by his forebears and passed on to me (along with a collection of books, which I am grateful for).

I did make the joke that it must have been the original masterbatch, because the pots boiled for days to make it!

 

[Nanditasr]

Ammonia solution needs to be treated with extra respect because it is highly volatile, unlike KOH or NaOH. Any one of the three can damage your skin and eyes from a splash, but ammonia also evaporates easily out of solution into the air. It is a strong respiratory and eye irritant. If you're using ammonia in soap, it's important to be aware of the potential danger to your eyes and lungs during soap making. Good ventilation is a must.

Thanks, DeeAnna. So I guess the risk applies more to the soapmaker than to the user of the soap. Anyway, I'll avoid it hereafter, because the EWG database says "High concerns: persistence and bioaccumulation", something that is not mentioned for either KOH and NH4OH. The reason I started making soap is that pure soap is somewhat compostable, and I'll be defeating that purpose if I have ammonium anything pollute the water bodies.

 

[SaltedFig]

... The reason I started making soap is that pure soap is somewhat compostable, and I'll be defeating that purpose if I have ammonium anything pollute the water bodies.

A curious thing, Nanditasr, is that soaps made from KOH are better for the soil (Potassium is a nutrient used in plant and animal biology) than soaps made from NaOH (Sodium salt isn't so terrific for soil), so if you were to look for compostable, KOH based soaps are the better of the two. Neither are particularly great for waterways (and the life in those waterways) ... but a away from water, KOH soaps can go in the compost

 

[Nanditasr]

A curious thing, Nanditasr, is that soaps made from KOH are better for the soil (Potassium is a nutrient used in plant and animal biology) than soaps made from NaOH (Sodium salt isn't so terrific for soil), so if you were to look for compostable, KOH based soaps are the better of the two. Neither are particularly great for waterways (and the life in those waterways) ... but a away from water, KOH soaps can go in the compost

Oh yes, that's a valid point -- potassium is good for the soil -- how did I forget! Such a bummer -- I wish one could make a solid soap with NaOH. :-( But yes, this is a good reason for me to trudge along to the crowded market in the city and pick up some KOH.

 

[DeeAnna]

Ammonium is also a natural part of the soil environment. Look up the nitrogen cycle and the role of bacteria breaking down nitrogenous compounds.

Anything to excess for a given situation can be a problem -- sodium, potassium, or ammonium can all cause trouble if present in a given environment in quantities that are too much (or too little). In amounts suitable for the situation, however, they are fine and even necessary to a healthy local environment. The point I'm trying to make is a person really can't make a blanket statement about any one of them being "bad" or "good" without first understanding the nuances.

For example, SaltedFig makes a good point that small amounts of sodium can be a real problem in freshwater and soil environments compared to small amounts of the other two. But, again, it's not enough to just know this one fact; you also have to put it in context. Sodium is a real troublemaker in arid environments because salts tend to accumulate in surface water and soil in regions where precipitation is limited. Sodium is not so much of a problem in areas where there is enough precipitation to dilute and transport sodium out of the "root zone."

 

[SaltedFig]

Yoopers, you mentioned that you didn't get a clear understanding of how masterbatching works (in the soap calculator testing thread), so I've added this as a programming guide.

Calculation details (the specifications for post 2):

Codes:
Note: All percentages expressed in decimal form for calculations (eg: 75% would be 0.75)

Masterbatch_Concentration = Masterbatch Concentration (lye concentration of the masterbatch solution, expressed in decimal form).
Note1: The default value of a masterbatch solution should be 0.50, as the masterbatch solution is usually made at a lye concentration of 50%
Note2: The upper limit of the masterbatch concentration should be 0.50 (close to the saturation point of the hydroxides in water)
Note3: The lower limit of the masterbatch concentration should be 0.25 (weaker solutions are less likely to successfully make soap)

Masterbatch_Weight = The total weight of the masterbatch mixture required (to add the correct amount of hydroxide for the recipe)

Masterbatch_Water = The weight of the water component of the master batch (excluding the hydroxide weight)

Hydroxide_Weight = The calculated weight of the Hydroxide to make the soap with the parameters specified (oils, superfat etc.)

Lye_Concentration = Lye concentration as entered in recipe, expressed in decimal form (eg. 33% would be 0.33)
Note1: Lye ratios etc. are to be converted to lye concentration for these calculations
Note2: The lye concentration cannot be greater than the masterbatch concentration

Total_Water = Total Water required for the recipe (to make the lye to the specified lye concentration)

Additional_Water = The amount of additional water required when a masterbatch solution is used, to get to the entered lye concentration
Note: Water is used to describe the liquid component, however other liquids can be substituted for the water amount

Calculations:
Total_Water = Hydroxide_Weight / Lye_Concentration
Masterbatch_Weight = Hydroxide_Weight/Masterbatch_Concentration
Masterbatch_Water = Masterbatch_Weight - Hydroxide_Weight
Additional_Water = Total_Water - Masterbatch_Water

Examples
2 examples of how the calculations work.

Example 1:
Lye concentration is entered in the recipe as 33%, the masterbatch is the default strength of 50% lye concentration.
Let's assume, for this first example, that the hydroxide ("lye") weight calculated for the recipe is 192.30g

Entered values:
Lye_Concentration = 0.33
Hydroxide_Weight = 192.30g
Masterbatch_Concentration = 0.50

Calculated values:
Total_Water = Hydroxide_Weight / Lye_Concentration
=> Total_Water = 192.30 / 0.33
=> Total_Water = 582.73g

Masterbatch_Weight = Hydroxide_Weight/Masterbatch_Concentration
=> Masterbatch_Weight = 192.30g/0.50
=> Masterbatch_Weight = 384.60g

Masterbatch_Water = Masterbatch_Weight - Hydroxide_Weight
=> Masterbatch_Water = 384.60g - 192.30g
=> Masterbatch_Water = 192.30g

Additional_Water = Total_Water - Masterbatch_Water
=> Additional_Water = 582.73g - 192.30g
=> Additional_Water = 390.43g

Example 1 results:
The weight of masterbatched liquid to add is 384.60 grams
The weight of additional liquid to add is 390.43 grams
(Combined weight = 775.03g)

Checking the answers for example 1:
The amount of "lye" the recipe needs is 192.30 grams
The amount of "water" the recipe needs is 582.73 grams
(The sum of these two is also 775.03 grams)

Example 2:
"Lye ratio" of 2.4:1 is entered (2.4 parts "water" to 1 part "lye")
Masterbatch percentage is made at the default of 1:1 (1 part hydroxide to 1 part water)
Let's assume, for this second example, that the recipe requires you add 12.34oz of "lye" (hydroxide) to make your lye solution.

Entered values:
Lye_Concentration = 1- 2.4/3.4
Hydroxide_Weight = 12.34oz
Masterbatch_Concentration = 0.50

Calculated values:
Total_Water = Hydroxide_Weight / Lye_Concentration
=> Total_Water = 12.34oz / (1 - 2.4/3.4)
=> Total_Water = 12.34oz / 0.2941176 ... (do not round until the calculation is completed)
=> Total_Water = 41.96oz

Masterbatch_Weight = Hydroxide_Weight/Masterbatch_Concentration
=> Masterbatch_Weight = 12.34oz/0.50
=> Masterbatch_Weight = 24.68oz

Masterbatch_Water = Masterbatch_Weight - Hydroxide_Weight
=> Masterbatch_Water = 24.68oz - 12.34oz
=> Masterbatch_Water = 12.34oz

Additional_Water = Total_Water - Masterbatch_Water
=> Additional_Water = 41.96oz - 12.34oz
=> Additional_Water = 29.62oz

Example 2 results:
The weight of masterbatched liquid to add is 24.68 ounces (by weight)
The weight of additional liquid to add is 29.62 ounces (by weight)
(Together these equal 54.30oz)

Checking the answer for example 2:
The amount of "lye" the recipe needs is 12.34oz
The amount of "water" the recipe needs is 41.96oz
(Together these also equal 54.30oz)

 

[DeeAnna]

"...Note2: The lye concentration cannot be less than the masterbatch concentration..."

Should this be "greater than"?

Nicely done!