Advanced Soap Design Kit

The percentage of oils left unsaponified (free oil) in the finished bar — a superfat of 5% means 5% of the oils stay as moisturizing oil, making the bar milder and more conditioning. A 0% superfat is harsh (no free oil); a 5-8% superfat is the balanced standard. The soap calculator sets the superfat from your lye discount.

Colorants — micas (mineral shimmers, skin-safe, vivid) and clays (earth pigments that also add slip and absorb oil). They disperse in oil (not water) and color the soap through the cure. Synthetic dyes (lab colors) shift in the high-pH soap (they morph or fade); micas and clays are stable. The colorant choice is the design palette.

At a thin trace, the poured soap is still fluid — pour contrasting colors into the mold and drag a tool (a skewer, a hanger) through them to swirl. The technique (in-the-pot, funnel, hanger) and the timing (thin trace, before it thickens) create the pattern. The swirl is the soap maker's signature; the tool and the pour are the variables.

After pour, the soap may "gel" — heat up and turn translucent as saponification accelerates (a darker, denser bar) — or not (a lighter, opaque bar). Gel is controlled by insulation (insulate to gel, refrigerate to avoid). Neither is wrong; gelled soap cures a little faster and the colors are more vivid. The choice is a design and a handling decision.