This is a topic that’s easy to forget. Then someone asks on the phone, or uses one word when they mean another. Or it might show up as a recent search on our website. Cold-processed base oils. Cold-pressed bar soap.
They sound almost right. But they’re not. It’s oils that are cold-pressed, soap that is cold processed. It makes sense when someone explains, but the distinction is easy to lose, mostly because if you’re not in the business of making soap or producing vegetable oils, the words don’t come up often enough to really sink in. Here’s something in writing to refer to if the difference starts to blur.
This is the preferred method for producing vegetable oils, also known as fixed oils and base oils. Using heat to extract oils is the non-preferred. When heat is used to extract oils from seeds, fruits, vegetables and nuts, more oil is produced (and therefore is available to sell), but it’s oil of lesser quality, with its flavor and nutritional quality degraded.
Cold pressing is preferred precisely because it’s a low-heat process, producing higher-quality oils, but in smaller quantities. In conventional, commercial oil extraction, raw materials are heated to temperatures up to 450°F (around 230°C), temperatures that change their chemical structure. It’s no longer a certainty that the oil produced is chemically what it’s advertised to be.
Cold Process – the One That Applies to Soap
Like its near sound-alike, cold process is a practice rooted in tradition. It’s also a process that emphasizes the absence of external heat sources. Cold-process soap is the result of the chemical interaction of fatty acids (most often in the form of fixed oils) and lye (sodium hydroxide for bar soap, potassium hydroxide for liquid). The result is soap, water, and glycerin. During the curing process – 4 to 6 weeks – much of the water evaporates.
In contrast, hot-process soap is all about the heat, and a much more immediate result. Cold-process soap has the advantage of a gradual, more natural chemical, resulting in – as proponents claim – a more nourishing, skin-compatible soap. Hot-process can be ready overnight. Soap preferences aside, the point remains that cold process refers to a soap making practice and cold press to a method of extracting oil from seeds, fruits, vegetables, and nuts.
One vs. Many
You’ll run into both terms if you’re around soapmaking much. One of the best ways to keep the expressions straight is to look at the expressions minus the word “cold.” “Press” refers to a single ingredient, an easy association to make. “Process,” by nature involves multiple ingredients. Keep those simple associations in mind, and then when the distinction begins to blur, come back and read this again.