Thirty bars made fourteen months ago, sunflower and olive with some coconut, stored in a cardboard box in an unheated garage. About a third have small orange spots, the rest look perfect, and they were all made in the same batch on the same day. They still lather and they smell faintly of old crayons. Is there a realistic shelf life I should be planning around, or did I just store these badly?
Those are the orange spots everyone dreads and they are rancidity in the unsaturated oils, not mould or lye. Sunflower is one of the more prone oils and an unheated garage swinging between cold and warm all year is about the worst storage you could pick. The bars are not dangerous, they just smell increasingly of old cooking oil as it spreads.
They are. Use them for washing hands at the utility sink and do not gift them. The spots spread outward from where they start.
Old crayons is exactly the smell. So the spotted third are effectively on a countdown.
Two things extend it and both are cheap. A rosemary oleoresin extract in the oils at the start slows oxidation, and a chelator like sodium citrate or a proper chelating agent ties up the trace metals that catalyse it. Since I started using both, my sunflower and rice bran heavy bars stopped spotting inside a year. I also stopped buying oils in bulk unless I will use them within a few months, because an oil that is already halfway through its own shelf life when it goes into the pot gives you a bar that starts life halfway to rancid.
I track my batches on index cards and the pattern is consistent enough to be useful. My coconut, palm and olive bars are unremarkable at two years in a cupboard. Anything with a meaningful proportion of sunflower or the high linoleic oils starts showing something in the nine to fifteen month range unless I chelate. Nothing has ever spotted before six months. The variable that predicts it best in my notes is not the recipe, it is where the box was stored, and the garage batches always went first.
Politely pushing back on blaming the oil first. In my experience the trigger is usually contamination rather than the recipe, which is why chelating fixes it so reliably. Trace iron from tap water, a stick blender with a worn shaft, or a metal utensil in the batter will seed spots in bars that should have been fine for years. If you make the same recipe again with distilled water and a chelator, I would bet a good deal on it not spotting. That would be a cleaner experiment than reformulating away from sunflower.
Both are true and they compound. Chelate and store properly and the fragile recipe becomes fine. Do neither and even a sturdy recipe eventually goes.
I did use tap water and my stick blender is ancient. That is two of the three.
Cardboard in a garage, cut them up and use them. Indoors, in a breathable box, out of the sun, a well built bar will outlast your interest in it.
@invoice_chaser · 6mo ago
I bought a large tin of a bargain oil once and used the last of it eight months later. Every batch from the back half of that tin spotted within a year and the batches from the first half never did. Same recipe, same water, same house. The oil was quietly oxidising in my cupboard the entire time and I was only smelling it once it was already in soap. Now I buy smaller and date the tin the day I open it.
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