Adding more lye to pre-made lye solution

[LilianNoir]

I went to pre-mix lye solution for soap I wanna make later this week, and realized I didn't have enough lye. (I DO have an inventory system w SM3. I should probably check it. But it doesn't tell you that you don't have enough if you're just creating a recipe and not "making" it, but anyway).


At that point the lye was already poured out of the container, and likely starting to react with the humidity in the air (I live in Fl and this has happened before, even in the house) and I didn't want to mess with trying to get the lye back in the container, so I just added it to my water.

So now I have a pretty weak lye solution, and I know how much I added and how much more I need.
Is there any reason why I can't add more lye to weak solution?

I can't think of why not but before I do it I want to make sure I'm not going to get a weird lye volcano or something.
It wasn't much lye (2.6oz) so if I can't add to this solution, our drain pipes need cleaning anyway.....

 

[earlene]

It is fine to do that, as long as you keep the correct measurements written where you can easily find them before you add the new dry lye. Keep the weak solution tightly covered so it won't evaporate out to the air. Weigh it again before adding the new lye to see how much water weight may have been lost to evaporation (I usually loose a few grams of water during evaporation when I first make my mb lye, so have to add it back in as water to get the correct weight of water+NaOH).

If it were me, I'd write the weights on masking tape & put that tape on the container, so I'd know what I have in the container. Then I'd write "Add 2.6 oz NaOH".

 

[LilianNoir]

Thanks @earlene!

Those are all really good things to remember. I've written down the amount of water and lye in my recipe notes, and I know the weight of the container (and it's written down in two places! lol) so I think it will work out!
Thanks for mentioning to double check the weight of the solution before I add the additional lye. I probably wouldn't have thought to do that.

 

[DeeAnna]

Unless the lye solution is really, really weak by soap making standards -- like under 20% lye concentration -- lye solution will absorb water from the air unless the relative humidity is really low. I kind of doubt that's a problem in Florida. The only time you'd lose water from a lye solution that's concentrated enough for soap making is when the liquid is really hot and steaming or if you live in the Mojave Desert or other super dry location. (Here are the geeky details: Uncovered lye solution; does it degrade? )

Regardless of whether it evaporates or absorbs water, Earlene's suggestion is the one to use.

A tight container will also minimize the loss of purity that happens when NaOH (or KOH) react with carbon dioxide to form sodium carbonate (washing soda). Washing soda is the white linty "floaties" on top of a fresh lye solution. The washing soda will eventually mix with the lye solution and gradually form a white sludge in the bottom of the container.

 

[Todd Ziegler]

Did you master batch your lye?

 

[LilianNoir]

Unless the lye solution is really, really weak by soap making standards -- like under 20% lye concentration -- lye solution will absorb water from the air unless the relative humidity is really low. I kind of doubt that's a problem in Florida.

Hah, good point. I should've thought of that myself. I use a bottle with a threaded screw top so that should be good.
(I saw earlene's comment in the what soapy thing have you done today thread about using the Essential Depot lye containers (when emptied!) to store lye solution and I like that. I've definitely started hoarding plastic containers since making soap!

Did you master batch your lye?

No, the last time i master batched I took too long to use it and it got the sludge/lint DeeAnna mentioned above. I was just making a batch in advance. I had hoped to make soap later that day. But I know exactly how much I need to add to get the lye concen I need for that batch.

 

[Todd Ziegler]

Hah, good point. I should've thought of that myself. I use a bottle with a threaded screw top so that should be good.
(I saw earlene's comment in the what soapy thing have you done today thread about using the Essential Depot lye containers (when emptied!) to store lye solution and I like that. I've definitely started hoarding plastic containers since making soap!


No, the last time i master batched I took too long to use it and it got the sludge/lint DeeAnna mentioned above. I was just making a batch in advance. I had hoped to make soap later that day. But I know exactly how much I need to add to get the lye concen I need for that batch.

I got some sludge myself and so once a week I would shake it up to keep it mixed.

 

[brooklynmaker]

Question for @earlene and everyone else on this thread.
When you master batch your lye solution do you add more water when you about to actually batch to make up for evaporation to bring to full weight?
For example: if I use 324 grams of lye + 486 grams of water for a master batch solution that = 810 grams total weight.
I lose about 30 grams in evaporation.
Do you recommend adding the missing weight in water before batching?

 

[DeeAnna]

Yes you should if it's truly water lost due to the "steam" created when the lye solution is very hot. You might want to look into why you're losing that much -- that's 6% of the total water weight and that seems like a lot.

I keep the container covered as much as I possibly can when the lye solution is steamy to minimize the loss. The mist is not just water; there's a bit of NaOH in the mist as well. I'd just as soon not have NaOH floating around in the air of my kitchen.

 

[marehare]

Question for @earlene and everyone else on this thread.
When you master batch your lye solution do you add more water when you about to actually batch to make up for evaporation to bring to full weight?
For example: if I use 324 grams of lye + 486 grams of water for a master batch solution that = 810 grams total weight.
I lose about 30 grams in evaporation.
Do you recommend adding the missing weight in water before batching?

I add 12 oz of lye to 32 oz of water, stir it, and leave by back door (open) while I melt my oils. When the oils are cooling to lower temp, I stir twice the lye water mixture and then bring it in to kitchen with window open. I then wait till both get to 120 and then mix. I heat my EO so they're the same temp as lye oil mixture and then add in. Never have a failed batch. I use cocoa butter, beeswax, palm oil, shea butter, coconut oil, olive oil and crisco. Best soap ever. I also add in orris root powder to fix the EO scent so it doesn't fade.

 

[earlene]

Question for @earlene and everyone else on this thread.
When you master batch your lye solution do you add more water when you about to actually batch to make up for evaporation to bring to full weight?
For example: if I use 324 grams of lye + 486 grams of water for a master batch solution that = 810 grams total weight.
I lose about 30 grams in evaporation.
Do you recommend adding the missing weight in water before batching?

I generally lose less than 10 grams of water to evaporation, when I make my mb lye using 900 grams of NaOH and 900 grams of water. The loss most likely occurs during the stirring because there is no lid to prevent evaporation escape. Once the solution is fully dissolved, the lid provides sufficient surface to gather the evaporate and as it builds up, it drips back down into the solution below. With the lid on the vessel I use for making mb lye, there is no vent through which the evaporate can escape; I wonder if yours is vented and that is where the high water loss is escaping.

When I prepare to make my mb solution, I look back at my notes from the last couple of times I made it to verify the usual water lost to evaporation. It tends to be very consistant, so I strarted to add that amount up front, but I did not do so in the beginning. And I still carefully weigh to make sure nothing has changed in terms of anticipated water loss.

 

[amd]

(I DO have an inventory system w SM3. I should probably check it. But it doesn't tell you that you don't have enough if you're just creating a recipe and not "making" it, but anyway).

I think your original question has been answered, but I just wanted to address this - in case anyone else uses SM3 and has the same problem. If you keep good inventory control in SM3, you can check your inventory with a recipe (or multiple) before making the recipe. In the top tool bar there is a menu option for SHOPPING [sorry I'm not at home computer, so I'm working off memory for exact wording and placement... I might be a bit off, so I apologize if you have to a bit of fumbling due to inaccurate instructions]. This will open a separate window where you can select a recipe on the left and add it to the "shopping cart" on the right. Once you've loaded the recipe(s) then you can click the "calculate shopping list" ...maybe towards the bottom lower right? sorry... and it will populate a list of ingredients needed. There is an option to check and show only items without inventory or insufficient inventory, and it will tell you how much you need.

I hope you find this helpful, I certainly have since I discovered it. It has saved me a lot of time and frustration for planning my business! (Now remembering to order the correct things is a different story...)