I have a composition book. It's sort of a journal of each batch, & has been an invaluable learning tool.
Here's a list of what I do.
I date the page.
I give each batch a number, so that's at the top of the page.
I list the name of the recipe. (I keep a 3 ring binder of recipes.)
If I made any changes to the recipe, I note that.
I list all additives & their amounts.
I note what my Super Fat percent was.
I note what water discount I took, if any.
I note at what temp I mixed at - very important when trying to troubleshoot fading scents.
I note the flashpoint of my EO's/FO's if known.
I note anything that happens out of the ordinary, like riceing, fast trace, etc.
While the batch is curing, I take time to review the process, check my notes & add anything I might've missed earlier.
I check the batch during curing & make any notes - like is it ready to come out of the mold sooner than expected, etc.
I note the time when I unmold it.
I note what the log is like when I unmold - any wonkynesses, if it's sticky, or whatever, or maybe it's just the ordinary unmolding & I don't need to make a note.
If it's a new recipe, new EO/FO or color, I add a note every week as it cures. Is the scent or color morphing, is the scent fading?
At 4 weeks, I begin adding a weekly note as to how it performs.
Keeping notes is the only way I can remember, over time, just how a color or scent behaved.
Like, I now know that I can NOT take a water discount when I use Sea Moss FO. It took me several botched batches before I pinpointed the problem. Now, that tidbit is noted on the recipe as well as in the journal. It was reading back through the journal that I discovered the common element from failed batch to failed batch - the water discount. The supplier said the FO would cause riceing, but my problem was much more serious - I couldn't get the FO mixed in before it was time to get the soap into the mold. Reading the journal flipped the light switch for me.
Sometimes, there's nothing much to note. It's the new recipes, new scents or new colors that can be real gotcha's, so those are always well documented.
Some notes get transferred to the recipe sheet as !Warnings! or !Dont' try THAT again!
HPT