I have been searching for a good discussion of lye stability, purity and the implications for superfat. I found what seems like very useful info embedded in a thread with an unlikely name:
https://www.soapmakingforum.com/threads/ash-or-mold-quick-responce-apprecated.46697/page-2
Here’s what I’ve taken away from what I read there and elsewhere:
Some of you are using lower SF in recipes. Is that to compensate for lye impurity or aging, because you like lower superfat, are trying to avoid DOS, or for some other reason? (I haven’t researched this topic very well, yet).
I’m using small containers of “Rooto” lye from Ace Hardware and emptying them pretty quickly (a few weeks at most and the container is stored in a sealed ziploc bag), don’t leave the container sitting open, and haven’t seen any clumping. I have seen the occasional dark specks. I’ve been leaving the SF at 5% when I use SoapCalc.
I looked for the chemical composition of Rooto lye and found this:
https://ace.infotrac.net/getmsds.aspx?sku=4239216 which possibly indicates 99% purity (on page 4). Am I reading that right?
Should I be correcting for lye impurity and lye “aging”? If so, is it reasonable to just drop down to 2-3 % SF?
I would be worrying about this less if I lived in Arizona. I live in coastal Virginia, and the hot humid months of summer will be here soon!
https://www.soapmakingforum.com/threads/ash-or-mold-quick-responce-apprecated.46697/page-2
Here’s what I’ve taken away from what I read there and elsewhere:
- Lye degrades over time due to exposure to air and humidity. We can slow the degradation down by keeping the container closed tightly and not leaving the container open for longer than necessary.
- The lye should be discarded if it gets clumpy.
- For masterbatched lye, keeping the headspace to a minimum will reduce the rate at which the lye-water degrades.
- The lye we buy is probably not 100% NaOH, and the percentage of NaOH will go down over time due to exposure to/reaction with CO2 in air.
- Soap calculators don’t take the impurity of lye into account/assume the lye is 100% NaOH. This results in greater % superfat than calculated.
Some of you are using lower SF in recipes. Is that to compensate for lye impurity or aging, because you like lower superfat, are trying to avoid DOS, or for some other reason? (I haven’t researched this topic very well, yet).
I’m using small containers of “Rooto” lye from Ace Hardware and emptying them pretty quickly (a few weeks at most and the container is stored in a sealed ziploc bag), don’t leave the container sitting open, and haven’t seen any clumping. I have seen the occasional dark specks. I’ve been leaving the SF at 5% when I use SoapCalc.
I looked for the chemical composition of Rooto lye and found this:
https://ace.infotrac.net/getmsds.aspx?sku=4239216 which possibly indicates 99% purity (on page 4). Am I reading that right?
Should I be correcting for lye impurity and lye “aging”? If so, is it reasonable to just drop down to 2-3 % SF?
I would be worrying about this less if I lived in Arizona. I live in coastal Virginia, and the hot humid months of summer will be here soon!