lye solution master batch?

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dubnica

Well-Known Member
Maybe this is a stupid question but I read a lot here about masterbatching your lye solution but I have no clue how does that work? If you make 50/50 solution...how do you then figure out how much of that to add to your soap so you don't end up with soap that is lye heavy?

No such thing as a stupid question!

I make a 50/50 masterbatch lye solution all the time, and it's actually very easy to figure out how much to add. This is how I proceed and the math equation that I use:

1) First, forget that you are using a 50/50 lye solution and just run your recipe through a lye calculator (like SoapCalc, etc..) as you would normally do, making sure to enter the superfat % that you would like to use and the lye concentration % that you normally like to soap at.

2) Once the calculator shows you the normal water amount and lye amount for your batch, utilise the following simple math equation to get the proper amount of 50/50 lye solution to pour out, and the extra water amount to pour out for your batch. FYI- this specific equation only works if you are using a 50/50 lye solution, but you can apply this same exact equation to whatever lye concentration you normally use for your batches, be it a 33% lye concentration or a 40% or a 34%- or whatever %. :

The equation:

Lye amount: Take your total lye amount that the lye calculator gave you and multiply it by 2 in order to get the amount of 50/50 lye solution to pour out.

Water amount: Take your total water amount that the lye calculator gave you and subtract from it the total lye amount that the lye calculator gave you to figure out how much extra water to add.

For example, say your recipe calls for 5 oz of lye and 12 oz of water. First, you would multiply 5 by 2 to get the amount of 50/50 lye solution to measure out, which comes to 10 oz, so pour out 10 oz. worth of the lye solution.

Then, to figure how much extra water to measure out for your batch, take the 12 oz that the calculator gave you and subtract from it the total lye amount the calculator gave you (which was 5): so.... 12 minus 5 equals 7, so you would measure out 7 oz of extra water for your batch.

HTH!
IrishLass

Oh..simple...thanks

Once you start using a 50/50 solution, you'll love it. No more fumes (other than initial mix) and batches can be made one after the other with almost no down time. And speaking of initial mix, don't do what I did the first time I mixed one. I made it in the garage assuming with the door cracked open it'd be fine. Dead of winter and freezing cold. Mixed up a couple of pitchers' worth and covered them with plastic to cool before pouring into storage container. My husband had some small tools, screwdrivers and such, layed out a few feet away and they all rusted instantly. Obviously iron and not SS. Weirdest thing I ever saw. Luckily, he didn't care. Powerful fumes mixing 50/50 solution.

Great explanation, Irishlass! I keep telling myself it would make my soaping so much easier to do this, but need to find a good container first! I do have a backload of laundry so it may be sooner rather than later.

What a crazy tool story too!

This is the first I've heard of pre-mixing lye. Is there a post here that explains how to do it? How much can be made ahead of time? How long will it last?

THANK YOU, Irish Lass!!!! That was a very quick and simple explanation....will try that this weekend.....

safire_6 said:
This is the first I've heard of pre-mixing lye. Is there a post here that explains how to do it? How much can be made ahead of time? How long will it last?

As long as it's properly stored and airtight, I see no reason why it wouldn't last a pretty long time. Having said that though, I don't have it sitting around for a really long time. I make 160 oz. of finished solution at a time, which fills 2 detergent bottles of the 100-oz (56 load) size. I don't like to use detergent bottles any bigger than that, or they get unwieldy to use. I get about 9 batches out of that using Upland 18" logs. My business is small, so I only make about 3 batches a week. (Except last July and August when I soaped like mad to get ready for fall craft shows.)

safire_6 said:
This is the first I've heard of pre-mixing lye. Is there a post here that explains how to do it? How much can be made ahead of time? How long will it last?

It's as easy as mixing the lye and water as you would normally do, only you are mixing equal parts of lye and water together- a 50/50 solution. You can mix up as much as you have lye, water, space, and proper storage containers to store it in.

First, you want to make sure you have lye-compatable containers with tight-fitting lids to store the solution in once it's mixed and cooled. I use cleaned out All-brand detergent bottles made of HDPE #2 plastic, which is stamped on the the underside of the containers. HDPE #2 containers are great for the job, and if you can get one with a spill-proof spout like my All containers have- all the better.

Stay away from containers made of PETE #1 and PS #6. They are not lye-compatable. Glass is not recommended either because it will etch over time and the glass will break.

I mix my solution up along with some Tussa Silk fibers in a large Rubbermaid pitcher made of PP #5, cover, let it cool, and then pour it into my detergent bottles through a fine mesh stainless steel strainer. Then I cover tightly and store in an out-of-the-way place at room temp. until ready to soap.

I did an experiment over the spring/summer to see how long I could let some of my 50/50 lye solutiuon sit and have it still be good for soaping. So far, 5 months works great. I made the solution back in March and made 3 batches with it just last month (August). It's now cured and the soap came out as normal as if I had mixed my solution up yesterday.

IrishLass

Just wondering, Irishlass, do you give the jug a quick shake or anything before you use it each time? I'm assuming a spatula wouldn't fit inside. But, maybe since it's strained you don't need to shake it?

I don't think I really need to, but yes, I give it a shake just for good measure. Actually, my 'shake' is really more of a swirling-type motion.

IrishLass

Gotcha. Thanks!

For simplicity and practicality, I mix up a lye supply tank at the normal concentration that will be added to the oil. Advantages are that you control your lye solution concentration through precise weight measurements of the solid lye and the water components, and you just do this one time. 2nd advantage is that you can create larger quantities of solution and use whole 50 pound sacks of lye at a go (no residual). A larger tank has a lower surface area to volume ratio than a smaller tank, so heat loss is slower and internal lye solution mix temperatures go higher.

Base water first. Mix one sack AM, tank goes too hot to touch. Give the tank all day to cool down if you need to add a 2nd sack lye, otherwise, danger of going boiling. Trim your supplementary water for your exact concentration. Put fans toward the tank, and let it cool all night to an approximation of room temperature for the next day. Other than when adding water or lye or stirring, the lye tank must be capped at all times, especially when it is hot, or you will get large evaporative water loss (which will screw your lye solution concentration) and lye fumes.

And stir the lye tank! Stir, stir, stir.

Sounds really interesting, but I'd never be able to mange a 50 pound sack of lye on my own and it's sounds a little scary to me to work with that large an amount at one time. :shock:

Sounds like a good system for you though. Must save you a ton of time.

heyjude said:
Sounds really interesting, but I'd never be able to mange a 50 pound sack of lye on my own and it's sounds a little scary to me to work with that large an amount at one time. :shock:

@chris-2010, I'm going to go out on a limb here and say that you're not working out of your kitchen, right?

Muzhik said:
heyjude said:
Sounds really interesting, but I'd never be able to mange a 50 pound sack of lye on my own and it's sounds a little scary to me to work with that large an amount at one time. :shock:

@chris-2010, I'm going to go out on a limb here and say that you're not working out of your kitchen, right?

Equation is confusing to me

Hi all,

I'm very confused by the equation.

Let's say that I always use the exact same recipe, and that my calculator says it requires 119 grams NaOH to 286 grams H20 (about 41.6%).

Let's say I multiplied that by 10, so I mixed 1190 grams NaOH to 2860 grams H20, which would yield me 10 batches at 41.6%.

Wouldn't I then just measure out 405 grams of this mix (119+286=405) for each batch of soap? I don't understand the need to add extra water.

Thanks all.
Mango

If you decide to make a masterbatch of lye stronger than what you use normally for soaping (like the 1:1 mix described- equal amounts of water and lye), then you'd need to add extra water to bring the lye concentration down to where you want it, using the calculation IrishLass gave to determine how much water to add.

for those that masterbatch their lye, can the cooled lye solution be stored with sodium lactate in it, or do they add the sodium lactate right before making the soap batch?

for those that masterbatch their lye, can the cooled lye solution be stored with sodium lactate in it, or do they add the sodium lactate right before making the soap batch?

I add my SL when I make the soap. I don’t think it would really matter if added when the lye is mixed.

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