"Trace" is a soapmaking term used to describe the stages of emulsion when the there is no more risk of the oils and lye separating in the soap batter. It is achieved by vigorously mixing the mixture (most effectively by a stick or emulsion blender).
Trace is separated into the three distinct stages: thin, medium, and thick. Differentiating these stages is relatively subjective. Soap batter can progress from one stage to the next, sometimes within seconds, depending on a plethora of factors including but not limited to:
- fragrance
- colorants
- additives
- recipe
- high temperature
- over blending
"False trace" describes an instance where the oils and lye appear to be mixed but have not yet completely emulsified. This will result in separation.
"Acceleration" is that instance where the soap batter seems to speed from emulsion to thick trace within seconds. In the case of "seizing", the soap batter has basically solidified in the mixing bowl, often before all the ingredients have been completely incorporated. This can result in the nightmare inducing "soap-on-a-stick".