Glycerin can change both the feel and consistency of liquid Castile soap. Learn why it is used, how it differs from simply diluting with water, and why more glycerin does not necessarily produce more lather.
Olive oil and coconut oil can both be used for liquid Castile soap, but they produce very different soaps. Learn how they compare in cleansing, lather and thickness—and why the better choice depends on what you want the soap to do.
Cold process soap is shaped by much more than its basic recipe. Learn how oils and butters influence hardness, lather and skin feel; how fresh ingredients, powders, fragrance and other additives affect a bar; and how formulation, troubleshooting and artistic design fit together.
Cold process soap can be made without palm oil, but removing it can change the hardness and longevity of the finished bar. Understand why replacing palm oil is not always straightforward and why a shorter-lasting bar is not necessarily a failed soap.
Cold process soap does not automatically need added glycerin because glycerin is already produced during the soap-making process. Learn why it remains in the bar and how adding extra glycerin can affect softness and moisture absorption.
Cold process soap can contain liquids, fresh pastes and purées, botanical powders, clays and physical scrubs—but they don’t all behave in the same way. Learn why the form, texture and amount of an additive matter to the finished soap.
Essential oils and fragrance oils can both give cold process soap its scent, but they are not interchangeable. Understand their different roles, how their scent can behave and why some fragrances can make soap thicken unexpectedly.
Superfat refers to leaving some oil unconverted in the finished soap. Learn why this matters for skin feel and how the principle can be considered when designing soap for dry, oily or more general skin needs.
What makes one cold process soap firm while another stays comparatively soft? Learn how hard and soft oils, butters and lathering oils influence soap hardness—and why making a harder bar is ultimately about balance.
