Old lye

[John Harris]

I was just on the Belle Chemical site and they say that lye doesn't go bad with time. I have a large amount of lye in my cellar that is around 18 years old! I wonder if it would still work. Guess I could test it.

What is the oldest lye you have worked with?

 

[Misschief]

When I started soap making, my mom gave me her last bottle of lye. She figured it was close to 20 years old. I had no issues with it at all. It was from Home Hardware and the 3 kg bottle was well sealed, no lumps, still free flowing. I used it for a couple of batches and then it sat for a few more years before I finished it. Never had an issue. Home Hardware is still my go-to for lye.

 

[John Harris]

When I started soap making, my mom gave me her last bottle of lye. She figured it was close to 20 years old. I had no issues with it at all. It was from Home Hardware and the 3 kg bottle was well sealed, no lumps, still free flowing. I used it for a couple of batches and then it sat for a few more years before I finished it. Never had an issue. Home Hardware is still my go-to for lye.

Incredible! Thanks for the reply!

 

[John Harris]

Progress note on my old lye usage

6 weeks ago I made a batch of soap (Frankincense) using 18 year old lye, As I mentioned above, Belle Chemical says that lye does not go bad. The Soap Queen, however, says it must be carefully stored. Mine is in a heavy duty plastic bag, but the top had been opened a bit. The bag opening was rolled up, however. The Soap Queen said that if it was bad, the lye would not get as hot when first mixed with the water, and the soap would be soft and sticky. Using Expired Lye in Cold Process Soapmaking - Soap Queen

So, I thought a would do a (40 bar) test. The lye-water mix did not get as hot as usual, it took a very long time to trace, and the bars were soft and sticky. Seems tho the Soap Queen knows her stuff.

Anyway, I put the bars in my super-duper soap dryer and just waited (impatiently) for time to go by. Thursday will be a full 6 weeks. I would say the bars are at 90% of where they should be as far as hardness and stickiness go. I figure I will give them another month before I make a final judgement. I am heavily invested in this experiment working as I have two 50 pound bags of old lye. It would be SO painful to have to throw all that out.

I'll attach some pics of the soap:

 

[CreativeWeirdo]

Looks like beautiful brown and gold marble!

 

[TheGecko]

So, I thought a would do a (40 bar) test.

My ideal of a ‘test’ batch is 20 oz…total.

 

[John Harris]

My ideal of a ‘test’ batch is 20 oz…total.

Yah, I know. I HATE doing normal test batches. I've had a couple of surprises (e.g. accelerations), but so far I've been able to handle any curve ball thrown my way. I suppose one day I will really get caught!

 

[ResolvableOwl]

Belle Chemical says that lye does not go bad. The Soap Queen, however, says it must be carefully stored.

I just don't agree with your “however” – as if this were mutually exclusive. Lye doesn't go bad by itself. As long as there are no serious contaminations (by things like rust flaking off from the container, death-wishing critters/insects, water damage, or stupid user error), it will keep being lye for an indefinite amount of time. The worst thing to happen (bad enough) is that it pulls water and CO₂ from the air, i. e. you are in danger to overestimate its purity and “bite”. But this is something that one could in principle mitigate with titration. Back in the time (19th century) when high-quality industrial lye wasn't easily available, chemists and pharmacy technicians knew how to deal with this, and LSers (KOH users) still do up to this date.

My ideal of a ‘test’ batch is 20 oz…total.

My largest batch so far was from some 11 oz of oils. Guess I'm an impostor all the way down.

 

[Talispa1]

Keeping CO2 out is the key to keeping it from changing to sodium carbonate and then later to baking soda. If you don’t mind having sodium carbonate or baking soda in your soap you can adjust for potency. Otherwise you will end up with high super fat levels and not as strong soap. It could be helpful for making soap for laundry detergent.

 

[ResolvableOwl]

having sodium carbonate or baking soda in your soap

Or Lazybones' ZNSC

(But better not without titration, which would overcompensate the laziness by far)

 

[John Harris]

Keeping CO2 out is the key to keeping it from changing to sodium carbonate and then later to baking soda. If you don’t mind having sodium carbonate or baking soda in your soap you can adjust for potency. Otherwise you will end up with high super fat levels and not as strong soap. It could be helpful for making soap for laundry detergent.

If I reduced the super fat level to 1 in soapcalc, would that help any?

 

[ResolvableOwl]

Yes. That way you're still on the safe side wrt full lye consumption (IF AND ONLY IF you weigh your lard ), but you have gained a bit more headroom with lye purity in question.

Depending on your paranoia, you could also blend the old lye with new lye. Just to feel a bit more secure, but still use up the vintage lye bit by bit.

 

[John Harris]

@ResolvableOwl I like the blended lye idea! I have to go out now to the lye store to buy new lye. The streets surrounding it, however, are ALL under construction. It is SUCH A PAIN to try and get near that store!

I will also cut the superfat down to zero percent in soapcalc. At 5%, the lye amount is 710.23 grams. At zero percent it is 747.61 grams. (A difference of 37 grams.) That will allow me to safely use more lye to eat up the oils. (Yes, "eat up" is a seldom used, but very technical soaping term.)

Does this all make soapmaking sense?

 

[earlene]

Don't throw it out without doing a purity test, John.



https://classicbells.com/soap/lyePurity.asp

 

[John Harris]

@earlene @DeeAnna I did a lye purity test using the formulas referred to us by DeeAnna . ( NaOH or KOH purity check | Soapy Stuff ) My old lye seems to weigh in at 78% purity. According to my numbers, I have to add 204 more grams to the SoapCalc calculation for lye.

I made a whole batch of soap with that uncorrected old lye amount about 7 weeks ago. It seems to have made a good bar of soap. It "gives" a little when squeezed hard and it is a tiny bit sticky/greasy. All in all though, I think it is an acceptable bar of soap. Still have to do the Using It In The Shower Test.

 

[ResolvableOwl]

@John Harris ← no longer a titration virgin

Your final value sounds like a really low number. Pure soda ash (sodium carbonate) would show up as 75% purity lye (titrated with a strong acid like hydrochloric acid, though). Did it foam/fizz a lot when you added the citric acid? Are the flakes/beads/pellets very sticky and clumpy, and appear “wet”? Is a naïve 50% solution (1 part degraded NaOH + 1 part distilled water) clear or turbid?
Have you faithfully kept to the citric acid drying step? If you have used the monohydrate instead of the anhydrous, your number would read 85% rather then 78%. Titration is only as accurate as the least known purity of reagents.

(Asking just to limit surprises in case you want to use up the old lye and rely on this value in soapcalcs.)

I'm baffled that a soap with 22% unplanned superfat (and probably less than 80% coconut oil) has a halfways decent performance. Looking forward to your further reports!

 

[John Harris]

@ResolvableOwl
Did it foam/fizz a lot when you added the citric acid? No
Are the flakes/beads/pellets very sticky and clumpy, and appear “wet”? No
Is a naïve 50% solution (1 part degraded NaOH + 1 part distilled water) clear or turbid? I'm not sure. Can you say more on this?
Have you faithfully kept to the citric acid drying step? I used anhydrous citric acid.

 

[John Harris]

@ResolvableOwl Well, I took the plunge and tested the 7 week old soap in question. Not the full In-The-Shower test, but the Wash-My-Hands-In-The-Sink test. The lather and bubbles were excellent. The scent (Frankincense & Myrrh) was glorious. My soap partner agrees. Next test: In The Shower.

 

[John Harris]

And again @ResolvableOwl
I found this in Google. Is this how I do it?

Stock solution, 50% (by weight): Add 100 mL of distilled water to 100 g of reagent grade sodium hydroxide (NaOH) pellets and stir until solution is complete.

 

[ResolvableOwl]

Is this how I do it?

Stock solution, 50% (by weight): Add 100 mL of distilled water to 100 g of reagent grade sodium hydroxide (NaOH) pellets and stir until solution is complete.

Yes. Except that you better add the NaOH (slowly and in several steps) into the water, and not the other way round (Don't trust everything in teh interwebz! Spills of boiling, concentrated lye, splashing around are no fun.). And 200 g solution is quite some wasted NaOH, except when you're planning to use it further on.

Sodium carbonate (one major decay product of lye with extended air contact) is easily soluble in water and dilute NaOH solution, but hardly soluble in concentrated lye. The old-fashioned way to get pure lye solution is to dissolve as much NaOH (of unkonwn purity) into water as possible (saturated lye). Possible Na₂CO₃ impurities first dissolve, but then precipitate the more NaOH dissolves and “grabs” the water off the carbonate to stay in solution. Then you can filtrate the (turbid) solution, and determine the concentration by titration, density, or temperature.

In inversion of this argument, the presence/absence of turbidity points to soda ash. On the other hand, the carbon dioxide bound in the soda ash should have appeared during titration already (fizzing) – but probably, the 6% solution that @DeeAnna recommends (for good reasons: dilution = precision, and to keep heat of neutralisation under control) is just too dilute for visible bubbling to occur (CO₂ is reasonably soluble in water and dilute solutions).

What I'm wondering rn is what the 22% of your lye are, that aren't NaOH. It can't be mainly water, since then it'd be very sticky. Soda ash? Not sure, it would help to see bubbles, or crusty bits of white stuff floating in concentrated solution.
Point is, I don't know if someone has a definitive answer if sodium carbonate eventually (during months of cure) might or might not take part as an active base in saponification, i. e. if one has to count the carbonate as active (but slow) lye – or it's just some “ballast” in the soap (like glycerol, or salt in salt bars). Sodium carbonate gives a slightly positive result in the zap test. On the other hand, zappy soaps can lose their zap over time, when surplus hydroxide catches CO₂ from the air, to form (milder, but still irritant) carbonate.