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Question about master batch lye volume and storage

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KimT2au

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Hi all

I would like to master batch my lye but am not sure how to calculate the final volume. If, for example, I bought a 2ltr (2kg) bottle of distilled water and dissolved 2kg of lye in it, it would clearly not all fit back into the 2ltr bottle the distilled water came in, what would the final volume be?

Am I correct in thinking that once the lye has dissolved, I will need to weigh the master batch and possibly add more distilled water as some may have been lost due to evaporation while the mixture is hot?

I have read that you cannot dissolve the lye in a sealed container (as the pressure/heat builds up etc), but want to confirm that I can store it in a tightly sealed container. I would hate for the container to get accidentally knocked over and the caustic water to go everywhere.

Kim
 

shunt2011

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I dissolve 2 lbs of lye with 2 lbs of water in a mixing jug. When cooled I transfer it to my marked lidded container (cleaned out laundry soap jug). I store it on a shelf out of the way of being spilled or knocked over

I also mark the bottle as poison and lye
 

SaltedFig

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Hi all

I would like to master batch my lye but am not sure how to calculate the final volume. If, for example, I bought a 2ltr (2kg) bottle of distilled water and dissolved 2kg of lye in it, it would clearly not all fit back into the 2ltr bottle the distilled water came in, what would the final volume be?

Am I correct in thinking that once the lye has dissolved, I will need to weigh the master batch and possibly add more distilled water as some may have been lost due to evaporation while the mixture is hot?

I have read that you cannot dissolve the lye in a sealed container (as the pressure/heat builds up etc), but want to confirm that I can store it in a tightly sealed container. I would hate for the container to get accidentally knocked over and the caustic water to go everywhere.

Kim
..."it would clearly not all fit back into the 2ltr bottle the distilled water came in" ...

NEVER store dangerous liquids in drink or water bottles.

In addition to the obvious risk, distilled water containers are often made of PETE #1 plastic - caustic solutions turns this plastic brittle (have you ever picked up an old, cheap garden pot or toy, that breaks apart in your hand as you pick it up because it's gone cloudy and brittle from being left in the sun for a few years? ... it goes like that, only quicker).

You need to re-use the lye container or a similar chemical resistant container with a secure (preferable child proof) lid. The best (common) plastic to use is thick #5 (polypropylene) plastic, but #2 will also do (it isn't as heat resistant, so be aware of that so you don't add your lye solution when it's hot). Some of the bleach containers or nappy wash containers are the right plastic, lid closure and wall thickness to cope with storing the lye solution (in the same manner as shunt2011 - mix and cool first, then transfer to the container).

... "I have read that you cannot dissolve the lye in a sealed container (as the pressure/heat builds up etc), but want to confirm that I can store it in a tightly sealed container" ...
Yes, there are gases and heat produced as the hydroxide dissolves in the water, so you don't want to have this occurring in a sealed container. Once the lye solution has cooled, it is ready to store in an appropriate container.

..."Am I correct in thinking that once the lye has dissolved, I will need to weigh the master batch and possibly add more distilled water as some may have been lost due to evaporation while the mixture is hot?"...
Irish Lass does this ... see https://www.soapmakingforum.com/threads/storing-lye-water.30081/#post-282644

Mark as dangerous caustic poison,etc
Draw drawings so even a child can tell it's dangerous, then keep it out of reach of children ;)

Like this (Hartac supply stickers if you need them):

It is preferable to have it in locked storage (I'm not sure if it's law yet - mine is, so I haven't checked in a while).

Don't store it over the height of your shoulders (this is to do with avoiding an accidental spill coinciding with the moment you're holding a dangerous liquid over your head).
 
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KimT2au

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My distilled water comes in a #2 plastic bottle @SaltedFig and I would obviously mark it as dangerous, lye etc, etc. However the basic problem is to work out in advance how much extra volume I need to prepare for when I mix the lye and the distilled water. There is no point mixing up a lye batch and then finding I do not have a bottle big enough to store it in.
 

cmzaha

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I mix mine in a 2 gallon hdpe bucket, let it cool completely then pour into my re-purposed dish detergent bottles. These are gallon bottles that are much thicker than a distilled water bottle even though they are #2, and I change them out at least once a year. I do not weight out my bucket after it has cooled because I am not about to put a 2 gallon bucket of lye solution back on the scale. That, in my opinion, is just to risky. I do at times get a little precipitation of lye in the bottom of my jug over time, but I do not worry about it, since I superfat low anyway. I like my bottles because they come with child proof lids.

I certainly agree not to store overhead and that is the one thing I do bad, and every-time I take down one on my jugs I think about a spill on top of my head. I also mark my bottle with big red crosses, my grand kids red cross means do not touch. This was taught while they were still toddlers. I also have the warning stickers from when we had our manufacturing company, but the kids really related to the red crosses. When they were little the room where I stored my lye was locked, which is an un-used bathroom with an outside door, always hated that door which we had to lock from the outside when my oldest was a teenager, and tile floor so if any accidents occur a hose can be brought in quickly. Also if an earthquake throws the containers off the shelf they should end up in my square bathtub, which is also never used. Did I ever mention I have an oddly built house.....
 

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You need to never, ever worry about volume. Always use weights. It does not matter what the volume is. If you mixed it on a 1:1 (weight) ratio, you take the amount of NaOH or KOH you need and double that for the weight of the NaOH:H2O mixture you need. Do not worry about volume loss.
 

SaltedFig

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My distilled water comes in a #2 plastic bottle @SaltedFig and I would obviously mark it as dangerous, lye etc, etc. However the basic problem is to work out in advance how much extra volume I need to prepare for when I mix the lye and the distilled water. There is no point mixing up a lye batch and then finding I do not have a bottle big enough to store it in.
The caution again putting caustic into a drinking water bottle still stands. I'm not saying this to bother you, but poison and dangerous liquids almost always have a different bottle shape to food and drink bottles - this is done very deliberately to make it immediately recognisable as something different from consumables.

Even if a water bottle is made from a caustic resistant plastic, please do not use water bottles to store this deadly water look-alike.

..."However the basic problem is to work out in advance how much extra volume I need to prepare for when I mix the lye and the distilled water."...

To work out the volume ... make up a mini batch of 100g water and 100g sodium hydroxide. Let the solution clear and cool, then pour it into a measuring jug, place it on the bench and, from eye-level, look at the bottom of the meniscus.
 
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earlene

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The volume question has been answered, so this is just an idea for storage:

If your dry lye comes in #2 or #5 bottles (I advise you check the bottoms first because not all do), then you can store you lye solution in them. That's what I do. It saves the extra labeling for long term storage. I buy some of my lye from Essential Depot (when they have it on sale, it's usually a very good sale) and their lye bottles are very good for storing my masterbatch lye. I still do add an additional label to ID date masterbatch was made and total weight of masterbatch in each bottle at time of filling. You don't have to do that, but because of my professional training certain processes have become second nature and just do it out of habit. It does give me an idea of how quickly I use it up or how old it is when I do use it. So you may find that of interest as you continue soaping.
 

DeeAnna

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I get what the OP is trying to say. Been there, done that too.

To restate the problem -- A 2 liter jug will hold 2000 grams of water, but 2000 grams of 50% NaOH solution won't fill the container. So what weight of water and NaOH does the OP need to weigh out to end up with a 2 liter volume of masterbatch solution?

The answer -- A 50% NaOH solution has a density of roughly 1.5. (For the science geeks, Occidental Chemical Corp info says the density is 1.53 to 1.54 at 60F/16C, depending on how the NaOH is manufactured.)

In other words, 1 liter of water weighs 1000 grams, but 1 liter of 50% NaOH solution will weigh 1.5 times that -- or about 1500 grams. The volume of each liquid is exactly the same -- 1 liter -- but the weight of each liquid is quite different.

That means the OP's 2 liter jug will hold about 3000 grams of 50% NaOH solution. Since a 50% solution is 1/2 water and 1/2 dry NaOH by weight, the OP should measure out 1500 grams of each to fill the jug to the brim.

That said, I don't fill my jug that full for safety. It's too hard to pour a super-full container of liquid without spilling, and I don't want to take chances with this type of liquid. I don't want to use a pour stick to prevent spills, because the jug is heavy when full and I can't coordinate holding it and a pour stick.

So I would put only about 2800 grams of 50% NaOH solution to fill a 2 liter jug -- that would be 1400 grams of water mixed with 1400 grams of dry NaOH.

***

Yes, add back any water lost to evaporation.

Yes, you can tightly cap a container of room-temperature NaOH solution. It needs to be fully cool, however, to prevent any pressure from building up in the container.

***

If a person has a jug of unknown volume to use as a lye container, here's how to calculate the weight of water and NaOH needed to make just the right amount of 50% NaOH solution for the jug ---

Put the jug on your scale and tare the scale.

Fill the jug with water to the level you want. (Hopefully you won't fill it to the brim for safety's sake.) Weigh the amount of water in the jug.

Times that weight by 1.5 to estimate the weight of 50% masterbatch NaOH solution needed.

Divide that answer by 2 to get the weight of water and of dry NaOH to measure.

Weight of masterbatch solution = Weight of water in the jug X 1.5
Weight of dry NaOH to make this solution = Weight of masterbatch solution / 2
Weight of water = Weight of dry NaOH
 
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penelopejane

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Your dry lye container is the best option for storing a lye solution. Because it is the right plastic, it is thick and it is labelled.

You can use most liquid laundry detergent bottles for lye solution as well but you really need to label it clearly. Even if you live alone someone one day might have to clean it up or throw it away and labelling is vital. You really should not use a mineral water bottle, sorry.
 

earlene

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Your dry lye container is the best option for storing a lye solution. Because it is the right plastic, it is thick and it is labelled.

You can use most liquid laundry detergent bottles for lye solution as well but you really need to label it clearly. Even if you live alone someone one day might have to clean it up or throw it away and labelling is vital. You really should not use a mineral water bottle, sorry.
Generally true for some dry lye containers, but the Lye Guy container is PETE plastic (recycle #1) way to flimsy and dangerous for liquid lye solution. But she isn't talking about using a mineral water bottle. She's talking about using the bottle the distilled water came in. I have noticed some are better than others, but I would still make sure it has a screw-on cap and is at least the #2 or #5 recycle code (the ones I buy aren't up to my standards, so I wouldn't use them for lye solution, personally.) But I supposed it depends on where you buy them as they are not always the same.
 

penelopejane

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Generally true for some dry lye containers, but the Lye Guy container is PETE plastic (recycle #1) way to flimsy and dangerous for liquid lye solution. But she isn't talking about using a mineral water bottle. She's talking about using the bottle the distilled water came in. I have noticed some are better than others, but I would still make sure it has a screw-on cap and is at least the #2 or #5 recycle code (the ones I buy aren't up to my standards, so I wouldn't use them for lye solution, personally.) But I supposed it depends on where you buy them as they are not always the same.
Wow, Earlene!
No doubt you have to check all the containers.
The #2, #5 and the thickness.
I was referring to my experience with Australian containers as KimT2 is from Australia but I should have been much clearer as no doubt it varies here as well.
 

earlene

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Right. I would never have thought a vendor would use a PETE container for dry lye until I felt how flimsy it was and checked. It was rather a surprise and the only time I have seen one used before or since.
 

IrishLass

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HDPE #2 comes in different thicknesses. My distilled water bottles are made of HDPE #2, and so are my liquid laundry detergent bottles, but my laundry detergent bottles are made of a thicker/heavier grade of HDPE than the water bottles. The thicker or heavier the HDPE, the more opaque it is.


IrishLass :)
 

steffamarie

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I bought a very thick #5 bottle from Walmart that I store mine in. It is clearly labeled “LYE” in large letters and stored in a chemical cabinet that we can lock if need be. I don’t have kids around ever and my cat can’t get to it.

IMG_9699.JPG
 
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Megan

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I bought a very thick #5 bottle from Walmart that I store mine in. It is clearly labeled “LYE” in large letters and stored in a chemical cabinet that we can lock if need be. I don’t have kids around ever and my cat can’t get to it.

View attachment 33188
Have you found this container to be sturdy over repeat uses? I use this one as well (only masterbatched in it once), but am always worried about the seam down the center.
 

SaltedFig

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Simplified Metric Method for calculating the amount of masterbatch lye to make for any given container (metric only):
Container Volume => Fill the container to the desired fill point (not the top), then measure the volume in millilitres.
Sodium Hydroxide (dry, in grams) = Container Volume x 0.75
Water (in grams) = Container Volume x 0.75

If a person has a jug of unknown volume to use as a lye container, here's how to calculate the weight of water and NaOH needed to make just the right amount of 50% NaOH solution for the jug ---

Put the jug on your scale and tare the scale.

Fill the jug with water to the level you want. (Hopefully you won't fill it to the brim for safety's sake.) Weigh the amount of water in the jug.

Times that weight by 1.5 to estimate the weight of 50% masterbatch NaOH solution needed.

Divide that answer by 2 to get the weight of water and of dry NaOH to measure.

Weight of masterbatch solution = Weight of water in the jug X 1.5
Weight of dry NaOH to make this solution = Weight of masterbatch solution / 2
Weight of water = Weight of dry NaOH
Note: DeeAnna's weight measurement method is technically correct, and is the technique to use where accuracy is important.

@Kim2au If you have measured the volume you get from the two equal parts, as described in my earlier post above, then that measurement can be converted to density (for your time and place) by dividing the volume in millilitres into your original weight in grams (eg. 200grams/131.1millilitres = density). This method is technically correct (larger volumes for testing give more accurate figures), but thank you to DeeAnna for providing the rough density (1.5), which is all we require in this instance :)

Because you are using the metric system and you only need to measure with a modest amount of accuracy (you are aiming to partially fill a jug), DeeAnna's instructions can be significantly simplified.

Reason:
Water has roughly the same weight as volume (1 litre = 1 kilogram, 1 millilitre = 1 gram).

Background:
The gram was originally defined as the mass of 1 mL of water (at a set temperature and pressure, see link)
Trivia: The word litre is derived from an older French unit, the litron, whose name came from Greek - where it was a unit of weight, not volume (see link)

Method:
Fill the container then measure the volume of water.
Use millilitres and grams to measure with the appropriate level of accuracy (litres and kilograms would be too large)
The volume in ml is the weight in grams

Simplification:
This simplifies DeeAnna's instructions (where the lye solution has a density of 1.5) to read that each of the water and lye (by weight) will be 0.75 times the volume of the container.

Example:
Eg. If you have a 2 litre container, and choose to fill it 1,800ml:

Sodium Hydroxide = 1,800 grams x 0.75 of sodium hydroxide = 1,350 grams
Water = 1,800 grams x 0.75 = 1,350 grams
(Check: Masterbatch total = 1,800 grams x 1.5 = 2700 grams, and 1,350 grams + 1,350 grams = 2,700 grams)

Simplified Metric Method for calculating the amount of masterbatch lye to make for any given container (metric only):
Container Volume => Fill the container to the desired fill point (not the top), then measure the volume in millilitres.
Sodium Hydroxide (dry, in grams) = Container Volume x 0.75
Water (in grams) = Container Volume x 0.75
 

steffamarie

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Have you found this container to be sturdy over repeat uses? I use this one as well (only masterbatched in it once), but am always worried about the seam down the center.
I mix my lye solution in a different pitcher with a wider mouth and use this jug only for storage. So far I have used it on 2 batches and over a period of 2 or 3 months and it has held up well.
 

DeeAnna

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SaltedFig -- Your method also works for American fluid ounces and ounces (by weight) because 1 fluid ounce of water = 1 ounce of water (by weight).

You're asking people to measure the volume of water rather than its weight. That's a good idea especially for people with smaller scales. Also you've simplified the math a bit in that 1.5/2 = 0.75. But otherwise we're both in agreement as to method. That's good.
 

KimT2au

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You need to never, ever worry about volume. Always use weights. It does not matter what the volume is. If you mixed it on a 1:1 (weight) ratio, you take the amount of NaOH or KOH you need and double that for the weight of the NaOH:H2O mixture you need. Do not worry about volume loss.
I do need to worry about volume as this is a question about storage, not usage. I know that when I soap I work in weight but I need to work out how big a container I need to have on hand to store the lye solution in once I have mixed it. When you purchase bottles of liquids or bottles for liquids they are sold in ltrs, not kg. Yes, I pour Xg into my soap batter, but I need to ensure I have enough storage volume to put the lye mixture in after I have mixed it up.

If a person has a jug of unknown volume to use as a lye container, here's how to calculate the weight of water and NaOH needed to make just the right amount of 50% NaOH solution for the jug ---

Put the jug on your scale and tare the scale.

Fill the jug with water to the level you want. (Hopefully you won't fill it to the brim for safety's sake.) Weigh the amount of water in the jug.

Times that weight by 1.5 to estimate the weight of 50% masterbatch NaOH solution needed.

Divide that answer by 2 to get the weight of water and of dry NaOH to measure.

Weight of masterbatch solution = Weight of water in the jug X 1.5
Weight of dry NaOH to make this solution = Weight of masterbatch solution / 2
Weight of water = Weight of dry NaOH
@DeeAnna , you are always my saving angel. Thank you so much for your fantastic answer. It was wonderfully detailed and clearly explained. I am sending you this cyber hug and kiss in gratitude (((( X ))))

I am planning to make a batch bigger than 2Ltr but place the batch in a couple of 2 ltr containers as due to the arthritis in my hands I do not trust myself lifting anything heavier. My example of the distilled water containers was just that, an example. I plan on purchasing something sturdier.

Once again, @DeeAnna thank you so much for your help.

@SaltedFig thank you for your explanation as well. Here is a huge cyber hug and kiss as a thank you. (((( X ))))
 
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