Trace is the point during cold process soap making when the oils and lye solution have emulsified enough that the mixture begins to thicken and leave a visible trail or 'trace' on the surface when drizzled from the blender.
Thin trace: the batter is still fluid and drips leave a faint pattern that sinks back quickly. This is ideal for intricate swirl designs, multiple colors, and additives that accelerate. Medium trace: drips leave a clear trail on the surface. This is the standard pouring consistency for most recipes. Thick trace: the batter is pudding-like and holds peaks. At this stage, pouring becomes difficult and swirls are impossible.
Factors that speed up trace: high solid fat content (coconut oil, shea butter, cocoa butter), certain essential oils (clove, cinnamon, bay), higher lye concentration (water discount), higher soapmaking temperature, and continuous stick blending.
Factors that slow trace: high liquid oil content (olive oil, rice bran oil), lower temperatures, hand stirring instead of stick blending, and using full water amount.
To control trace, alternate short bursts of stick blending with hand stirring. Check consistency frequently. For designs requiring thin trace, stop blending as soon as the batter is emulsified — you do not need a visible trail.