What 'cold process' actually means (and why we cure for 4 weeks)

'Handmade' on a soap doesn't tell you much. 'Cold process' does — it tells you how the bar got from oils to soap.

The chemistry, briefly

Soap is what happens when fats meet a strong base. Mix oils with sodium hydroxide ('lye'), and over the next 24 hours every molecule of fat converts to a molecule of soap plus a molecule of glycerin. That reaction is called *saponification*. By the time it's done, there's no lye left in the bar — it's all been used up turning the oils into soap.

What 'cold' means

We don't apply external heat. The reaction generates its own (it's exothermic). Cold-process soap retains all the natural glycerin produced by saponification — the same glycerin that big soap brands strip out to sell separately as a moisturizer.

That's the difference you feel in the shower.

Why four weeks

After the first 24 hours the bar is 'soap' in the chemical sense, but it's still soft and full of water. Curing — sitting on a shelf in airflow — lets that water evaporate. Four to six weeks gives you a hard, long-lasting bar with a creamy lather.

Sell a bar at 24 hours and it'll work, but it'll mush apart in a week. Sell it at four weeks and it'll last you a month.

We cure ours for at least four. Sometimes longer if the recipe calls for it.