Master Batching Lye Question

I've been reading in the archives and found a post by soapmaker man. I'm hoping someone can explain it to me... I'm a smart person, but for some reason, I can't wrap my brain around this.

He says,
"by Soapmaker Man » Mon Dec 24, 2007 11:38 am
I make a premix lye solution of 50% strength. This is equal amounts by weight of liquids (I use aloe vera juice) and lye. I usually make batches of 25 ounces each, let cool, then store in a bleach container with the built in pour spout. Here goes how to figure how much is needed..... 

Say your recipe calls for, lets keep this simple, 10 ounces of lye and 30 ounces of water. With a 50% strength solution and a recipe calling for a 30% solution, needing the 10 ounces of lye, you figure it like this; 

I know that my 50% is 1/2 liquids and 1/2 lye. I weigh out 20 ounces of 50% solution, or 10 ounces of aloe vera juice and 10 ounces of lye. The recipe calls for 30 ounces of water. I take 30 ounces minus the 10 ounces that is in my 50% solution, knowing that I need to add 20 ounces of liquids, aloe vera juice in my case, to the 50% solution to get it to a 30% solution. This is where I add my goat milk to bring it down to a 30% solution to soap with. 

That is it, very simple basic math! I love having everything ready in two containers...my masterbatch of oils/butters, my favorite recipe, and my jug of 50% lye solution. I just shake the crap out of each one before pouring them out! 

Hope this helps you understand. I've been doing this for a year now! 

Paul..."

I normally make a two pound batch, which is about 12 ounces of water. How much of a 50/50 lye solution would I use and then how much additional water/liquid should I add to get it to 38%?

Thanks!

I work from a pre-mixed 50% masterbatch all the time.

It can sound confusing at first, but to make things simple I break it into a simple, 2-part math equation.

First, though- you need to enter your regular recipe into a soap calculator just the same as you would normally do as usual, i.e., with your preferred superfat level and preferred lye solution strength or water amount that you like to soap with, etc... and then write down the water and lye amounts that the calculator gives you for your recipe.

Now, take your written lye and water amounts that the calc gave you, and apply this simple, 2-part equation:

1) Lye Amount multiplied by 2 equals how much of the premade 50% lye solution to weigh out for your batch.

2) Water Amount minus the lye amount that you had written down equals how much extra water to add to your batch.

This math equation will work for any batch no matter what size it is or what lye concentration you want to soap with........just as long as you are working from a 50% masterbatch solution.

For more info, here is a different thread: viewtopic.php?t=29800&highlight=masterbatch

HTH!
IrishLass

thank you for that detailed reply. I think I've got it. I don't fully understand it, but for me, I will understand it when I do it.


Can you check this for me?

12.16 oz water, 4.6 oz lye is the original recipe

4.6 x 2= 9.2 oz of pre-made 50/50 solution

12.16-9.2 = 3.14 oz of additional liquid.

Loolee said:

thank you for that detailed reply. I think I've got it. I don't fully understand it, but for me, I will understand it when I do it.


Can you check this for me?

12.16 oz water, 4.6 oz lye is the original recipe

4.6 x 2= 9.2 oz of pre-made 50/50 solution

12.16-9.2 = 3.14 oz of additional liquid.

Click to expand...

Close, but not quite

4.6 x 2 = 9.2 oz of pre-made 50-50 solution (that is correct, but 4.6 oz of this is lye and 4.6 oz of this is water)

12.16 - 4.6 = 7.56oz of additional liquid (your 50/50 solution only contained 4.6 oz of water, so that is what you subtract from the original water amount

I know it seems confusing at first but to me this is SO much easier once you get the hang of it that it is totally worth it! HTH

new12soap said:

Close, but not quite

4.6 x 2 = 9.2 oz of pre-made 50-50 solution (that is correct, but 4.6 oz of this is lye and 4.6 oz of this is water)

12.16 - 4.6 = 7.56oz of additional liquid (your 50/50 solution only contained 4.6 oz of water, so that is what you subtract from the original water amount

I know it seems confusing at first but to me this is SO much easier once you get the hang of it that it is totally worth it! HTH

Click to expand...

Ditto everything new12soap said.

You got part one of the equation correct, but on part 2 of the equation you accidentally subtracted the resulting weight of the lye solution that needs to be poured out for your batch, instead of subtracting the original lye amount that you had written down earlier when you first got your water and lye amounts from the calculator. The amount that you had written down earlier is the one that needs to be subtracted from the water amount. Sorry if I wasn't more clear on that.


IrishLass

That makes my head hurt

So. glad. I. asked!!! I almost didn't!

Makes perfect sense now, but I'm going to print it out just in case!

Thanks again!

tkine said:

That makes my head hurt

Click to expand...

I can relate. It made my head hurt, too, the first time I tried to understand it all. What actually helped me was for me to stop trying to wrap my head around it and just follow the 2-part math formula. Understanding came later.


IrishLass

The way I have to remember it is that if I pour out the 9.2 oz of the pre-mixed 50% solution is that 4.6 oz is lye and 4.6 oz is the liquid I am using. I then need to add enough additional liquid to bring the total liquid to the amount required for the recipe. You use 2 times the amount of lye called for because that contains the correct amount of lye and adjust your liquid. You will get it, it took me awhile too.

I believe I understand now. I'm not the greatest with mathematics, & I read this thread while in
the middle of a lovely head cold.

How much do you all keep on hand ahead of time? I thought I read someone stores it in a detergent
bottle or fabric softener bottle. Do you mix it in the bottles also?

I normally add my silk to my lye water when I make soap. Would I still be able to add the silk to the lye water,
& store it all together?

Does the lye dissolve totally? Would it re-solidify?

On another lye note, I'm thinking of buying a 50# bag of lye. How does everyone store larger amounts of Lye?
What kind of shelf life does it have?

Thank you in advance for any info!

tkine said:

How much do you all keep on hand ahead of time?

Click to expand...

I store enough to make about seven 2.5lb batches. The solution lasts a very long time, too. I've done experiments on longevity by using 9 month old solution and it was perfectly fine.

tkine said:

I thought I read someone stores it in a detergent
bottle or fabric softener bottle.

Click to expand...

I store mine in a reclaimed detergent bottle made out of HDPE #2 plastic. I especially like that it has a no-drip spout. Not all plastics are created equal, though. You'll need to stay away from certain plastics, such as PETE #1, for example. It's not lye compatable. Look on the bottom of the bottle to find the recycle code before using for your lye solution. Two of the best ones to use are HDPE #2 and PP #5.

tkine said:

Do you mix it in the bottles also?

Click to expand...

No. I mix mine up beforehand in a polypropylene (PP) #5 container (Rubbermaid Pitcher) because I've read that polypropylene can take the high heat generated from mixing lye better than HDPE. Once the solution is made and has cooled down, I transfer it for long term storage in my HDPE container.

tkine said:

I normally add my silk to my lye water when I make soap. Would I still be able to add the silk to the lye water, & store it all together?

Click to expand...

Yes, absolutely. I add silk to all my masterbatches.

tkine said:

Does the lye dissolve totally? Would it re-solidify?

Click to expand...

This is a good question. I'm glad you asked this because there is some slight evaporation that takes place when mixing a 50/50 solution that needs to be taken into account, since lye needs an equal amount of weight in water to be able to dissolve properly. After my very first masterbatch in which I mixed equal weights of lye and water, I found I had a 6 gram deficiency of water immediately after all was mixed due to evaporation (I weighed everything both before and after). No problem, though- I just added 6 grams of water back in to compensate and all went well.

Nowadays, I just add 6 grams more of water up front than the weight of the lye when I'm making my masterbatch, and surprisingly it all evens out perfectly when weighed in the end. My mixing method must be quite consistent for the evaporation rate to remain the same each time I make my solution.

I have not had problems with mine re-solidifying, but I make sure to keep it tightly covered.

tkine said:

On another lye note, I'm thinking of buying a 50# bag of lye. How does everyone store larger amounts of Lye? What kind of shelf life does it have?

Click to expand...

I've not ever bought mine in bags, so I cannot comment on that. I buy mine in bulk, but it comes packaged in well-sealed 2 lb bottles (which I like a lot). Hopefully someone who buys bags will chime in on that.

If lye is stored properly and kept safe from humid air, it seems to last forever and a day. I've used lye as old as 3 years old and it was perfectly fine with no loss of potency. It was stored in a cool, dry place (my hallway closet) in well sealed bottles.

IrishLass

Thank you for the advice IrishLass

I have one more question you might be able to answer for me. I normally add sugar to my water, before adding my lye. Would
I do the same for Masterbatching? Or should I add it to the additional water & let it dissolve before I add my masterbatched mixture for each soap batch as I make it?

I buy my lye in 50# bags and then I pour it out into large plastic pails that I can seal airtight.... I like buying in this quantity because of how much it saves me.

I am going to start master batching my lye to save time.