Question about age of lye

[JuneP]

I just got some new lye, but I do have a question about the age of lye. The new lye I bought is flaked; but the other lye I have on hand is tiny pellets and they are in small, plastic bottles and I'm curious as to how long other soapers have found their lye to be effective. Also, other than the soap not saponifying, what other problems if any are their of using lye that maybe outdated.

Thanks,
June

 

[Susie]

It will look clumpy as it has absorbed too much moisture.

 

[The Efficacious Gentleman]

The only problem is that you are essentially using a lower amount of lye. You measure out 100g of lye beads, but they are no longer just NaOH- you might have 90g NaOH and 10g sodium carbonate or whatever where the lye reacted with carbon dioxide in the air. That's why soap doesn't saponify as well with lye that is old and badly stored, but only because there is technically not enough lye.

To counter it, you have to use more of your beads than the recipe calls for. The trouble is knowing how much more - so how much of your lye is still actually lye? That is much harder to work out I'm afraid

 

[shunt2011]

I can only speak on my experience. I have lye that is 2 or more years old. There is some very minor clumping in the bottles but I have never had any issues with it not working properly. As stated your SF may be a bit higher. I totally depends on how much clumping is occuring I'm sure.

 

[Misschief]

I received some lye from my mother maybe 10-12 years ago, a 3 kg plastic container; it was about half full. They lived in an area prone to a lot of rain (the Wet Coast). I used the last of it not quite a year ago. There was a little bit of clumping but I never accounted for its age when making my soap and I never had an issue.

 

[DeeAnna]

Two issues that seem to pop up a lot that are really hard to answer are: Is preservative is needed in diluted liquid soap? and How pure is my NaOH?

NaOH or KOH does not go bad simply with time. What makes either one go "bad" is exposure to the water and carbon dioxide in the air. If you can keep an alkali properly protected, it will last for centuries. If you don't protect it from water and CO2 (or other things it wants to react with), it will lose a lot of its purity within mere hours or days. The consequence of this loss of purity for soapers is that low purity NaOH won't fully saponify the fats in your recipe. You can expect a range of results from "the soap remains soupy and just won't come to trace or saponify" to "the soap looks fine but if I could measure the superfat, I would find it is is overly high."

When NaOH or KOH absorbs water from the air, it gains water weight, so 1 gram of NaOH that is clumpy from absorbing water is not 1 gram of pure NaOH. Some of that weight will be useless water. When NaOH or KOH absorbs CO2 from the air, NaOH will react with the CO2 and become sodium carbonate (washing soda) and KOH reacts with CO2 to become potassium carbonate. The carbonates don't easily make soap, so this reduces the amount of alkali available for soaping as well. One gram of NaOH that's contaminated with sodium carbonate is not 1 gram of pure NaOH.

That said, some clumpiness doesn't automatically mean the NaOH has become so impure it shouldn't be used to make soap. It might be ... or it might not ... so how can we tell for sure? The best way is to test it; otherwise we're really just guessing. Once we have a number for the purity, that number can even be used to adjust the weight so enough actual NaOH is used to make good soap.

***

Nikos (Ngian) started a recent thread about an interesting presentation by Kevin Dunn (it's on the Essential Depot blog). Dunn was talking in the presentation about a simple way of testing the purity of solid NaOH purity using citric acid. It's a method that anyone can do in your kitchen as long as you have a decently accurate scale and some citric acid. I tried his method and adapted it to testing solid KOH as well. It can even be adapted to testing masterbatched lye solution, if there's interest in that.

Dunn's quick test seems to work well, although I figure it's only going to give an answer that's accurate within a percent or two, if you have a scale that can weigh to 0.1 gram or better. That wouldn't make an analytical chemist happy, but Dunn's method is reasonably good enough for soapers using NaOH or KOH for soap making. And it's simple, fast, and easy to do.

Here's a shameless link to my website where I have more about this test: http://classicbells.com/soap/soapyStuff.html Look at "NaOH or KOH purity check" for a video and written tutorial to the test I've been talking about. Look at "NaOH deliquescence" for a short video on how fast NaOH can absorb water from the air. Check out "'Dry bucket' for NaOH or KOH storage" for a video that shows my version of KChaystack's method of storing NaOH and KOH in a large plastic bucket. If you have any questions about any of this, please ask.

 

[topofmurrayhill]

I received some lye from my mother maybe 10-12 years ago, a 3 kg plastic container; it was about half full. They lived in an area prone to a lot of rain (the Wet Coast). I used the last of it not quite a year ago. There was a little bit of clumping but I never accounted for its age when making my soap and I never had an issue.

I think you probably had an issue, but if it's an issue you don't mind then it's fine. Not everyone focuses on the same things. But here is the issue.

Many people say they used old NaOH and it worked fine. With the situation as you describe it, and in many such cases, I think we can say that the superfatting of the soap is unpredictable and could be significantly greater than the lye discount. That's not necessarily obvious, and the soap can be perfectly nice.

So again, if it's good for you then it's good. But for those who want a high degree of control over the process (sellers for instance), such as knowing that the superfatting of the soap is roughly similar to the lye discount, that requires either confidence in the freshness and careful storage of the caustic, or a little chemistry to determine it's strength and how much to use.

 

[JuneP]

Wow, thank you everyone for your input. My older lye is less than a year old so it should be fine. And I just got new lye - flakes this time. I don't imagine I will ever order so much that I would have to worry about having lye that might be too old, but I was very curious about all of you who have been making soap a long time and I assume buying larger amounts of lye than I would every buy. Now that I'm healing pretty well and catching up with my life, I'm starting to think about making some soap again and realized that i didn't know anything about the pitfalls of using old lye, or even what constitutes old lye!
So, once again, thank you for taking the time to share you experiences and Dee for her video as well!

 

[ozziesgirl]

There are a lot of videos on YouTube for making your own silica packets. It is cheap and easy to do. It would be pretty inexpensive to put together one of the dry buckets and put your homemade silica packets in it, then you wouldn't have to worry about moisture getting to your lye.

 

[topofmurrayhill]

There are a lot of videos on YouTube for making your own silica packets. It is cheap and easy to do. It would be pretty inexpensive to put together one of the dry buckets and put your homemade silica packets in it, then you wouldn't have to worry about moisture getting to your lye.

I didn't get exactly the setup you suggest -- maybe it's something that works -- but keep in mind that the hydroxides we use attract moisture from silica packets, not the other way around.

 

[BrewerGeorge]

...
Dunn's quick test seems to work well, although I figure it's only going to give an answer that's accurate within a percent or two, if you have a scale that can weigh to 0.1 gram or better. That wouldn't make an analytical chemist happy, but Dunn's method is reasonably good enough for soapers using NaOH or KOH for soap making. And it's simple, fast, and easy to do.

Here's a shameless link to my website where I have more about this test: http://classicbells.com/soap/soapyStuff.html Look at "NaOH or KOH purity check" for a video and written tutorial to the test I've been talking about. Look at "NaOH deliquescence" for a short video on how fast NaOH can absorb water from the air. Check out "'Dry bucket' for NaOH or KOH storage" for a video that shows my version of KChaystack's method of storing NaOH and KOH in a large plastic bucket. If you have any questions about any of this, please ask.

Wow! You are a font of knowledge!

 

[ozziesgirl]

I didn't get exactly the setup you suggest -- maybe it's something that works -- but keep in mind that the hydroxides we use attract moisture from silica packets, not the other way around.

I don't understand. I thought the whole point of a silica packet was to collect moisture from the surrounding environment, thus keeping the moisture out of whatever product you want kept dry. How is lye attracting moisture from the silica?

 

[DeeAnna]

NaOH is a desiccant too. It is much, much more powerful than the (safer) desiccants usually used for drying air -- silica gel can't remotely compete with NaOH in its ability to absorb water from the air.

If you put an open dish of dry NaOH granules and a second open dish of silica gel in a container and close the container so it is air tight, the NaOH will remove most of the moisture out of the the air and also out of the silica gel. After enough time (maybe an hour or two), the NaOH in the container will be damp/wet and the air and silica gel will be very dry.

In a "dry bucket" that is being discussed here, you would never store the unpackaged NaOH right in the bucket. Keep the NaOH and KOH in the protective packaging as provided by the supplier. The desiccant in the bucket is there to keep the the air surrounding the containers reasonably dry for long term storage. In this situtation, the desiccant never has to compete directly with the NaOH for water, so the desiccant can do its job of absorbing and holding onto any water vapor from the air.

Maybe what is confusing here is the question of why use the desiccant at all then. If the desiccant can't remove water from NaOH, what's the point? It is true the desiccant in the bucket cannot dry out the NaOH once NaOH has absorbed water.

But what a soaper CAN do is create a storage system that discourages FUTURE absorption of water, especially for long term storage. The container the NaOH is stored in is the first and main defense against moisture absorption. The desiccant in the closed dry bucket is the second line of defense. By keeping the air dry surrounding the NaOH containers, there is less water available to migrate into the NaOH containers -- no packaging is perfect. Thus there is less water for the NaOH to absorb over time.

 

[ozziesgirl]

NaOH is a desiccant too. It is much, much more powerful than the (safer) desiccants usually used for drying air -- silica gel can't remotely compete with NaOH in its ability to absorb water from the air.

If you put an open dish of dry NaOH granules and a second open dish of silica gel in a container and close the container so it is air tight, the NaOH will remove most of the moisture out of the the air and also out of the silica gel. After enough time (maybe an hour or two), the NaOH in the container will be damp/wet and the air and silica gel will be very dry.

In a "dry bucket" that is being discussed here, you would never store the unpackaged NaOH right in the bucket. Keep the NaOH and KOH in the protective packaging as provided by the supplier. The desiccant in the bucket is there to keep the the air surrounding the containers reasonably dry for long term storage. In this situtation, the desiccant never has to compete directly with the NaOH for moisture in the air, so the desiccant can do its job of absorbing and holding onto any water vapor from the air.

Maybe what is confusing here is that the desiccant in the bucket will not dry out the NaOH once it has absorbed water. Once NaOH has absorbed water, there's not much that can be done to dry it out again. But what you CAN do is create a storage system that discourages FUTURE absorption of water. The container the NaOH is stored in is the first and main defense against moisture absorption. The desiccant in the closed dry bucket is the second line of defense.

I can see that my post must have been unclear, because I was talking about putting the container of lye inside the bucket, not just dumping lye straight in. In my mind, it made sense that no one would do that, but I guess that wasn't an assumption I should have made.

So, sealed container of lye in dry bucket, and silica packets in dry bucket. This is a viable system for keeping lye dry, correct?

 

[DeeAnna]

Your post wasn't really clear about your point of view, but even if it was, there are many people reading this thread with varying backgrounds. I decided to give a full explanation rather than make assumptions about everyone's level of understanding.

In particular, a few people in the past HAVE assumed you'd take the NaOH out of its container and store it loose in the dry bucket, so I really want to prevent any misconceptions on that point.

"...This is a viable system for keeping lye dry, correct?..."

Yes. I wouldn't lend my support to this method if I didn't think it was useful. In the analytical chemistry lab where I used to work, we stored some kinds of chemicals this way. The chemicals were in tightly capped containers (glass, metal, or plastic, depending on the chemical) and the containers were kept in a desiccator cabinet.