This is just me, but I don't worry about shelf life with LS any more than I worry about shelf life with bar soap. Maybe it's because of the ROE and vitamin E I add to my oils, or possibly the essential oils, some of which are known to have "preservative qualities".
SHORT STORY:
I was purging my B & B supply cabinets the other day when I came across a 4-oz, sealed, bottle of shampoo made in 2007 that I forgot I had. It is my favorite shampoo -- flaxseed oil with 10% coconut and 10% rosin. I took the seal off, gave it a sniff, and, since it smelled fresh, I used it to wash my hair. No worries.
NOTE: ROSIN saponifies much like an oil but without any resulting glycerin. It gives a smooth cold cream finish to the lather and also acts as a detergent and preservative. Calculate - Rosin has the same SAP value as Wheat Germ Oil. (NOTE: May cause contact dermatitis in sensitive individuals).
I know many soapers I respect use preservative, and that's their choice. But it makes no sense to me. Before I learned to make soap, I tried a few so-called "natural" shampoos on the market -- Jason, Avalon, etc. If I remember correctly, they contained a preservative and they always smelled funky after about 6 months. Ugh. Plus, there is no preservative specifically formulated for lye-based liquid soap. Why would there be? As an alkaline product, i.e., nasties don't survive in an alkaline environment, why waste the money?
On the other hand, Dr. Bronner's liquid soap has been around since the hippie days and contains no preservative, zero, zip, none, nada. That's the liquid soap I aspire to. Also, some of the largest manufacturers on the groups I've been a member of always pipe up during this topic to say they never use preservative.
As for the "rather safe than sorry" argument for using a preservative, I could use the same argument for NOT using preservative. I've read enough about what can happen when a preservative is introduced into a non-compatible environment to have the same fear!
Just my take on it. 'Nuff said.
