Originally Posted by The Efficacious Gentleman
Trace is easier to know because it can be seen. Emulsion is the point where the oils and the lye solution are mixed enough that they won't separate out again (all things being equal) - it's harder to recognise which is why most people refer to trace and aim for that point. For some swirls and so on, emulsion is preferred as it gives you more time to work.
Newbie recently posted a video on how to spot when you're at emulsion. Well worth a look
thanks again! ack, i thought that video was supposed to be showing trace and was wondering why the batter looked a bit thin to me. i just discovered the abbreviations thread also has definitions but it doesn't have emulsion, trace, or the cook/after the cook. maybe good ones to add to the definitions for the real newbies?