Making tube 4,000 match tube 1
Updated
The first wholesale reorder is where inconsistency becomes visible, because the buyer has the last batch on the shelf next to the new one.
What actually drifts
Material. A new lot of shea, a different beeswax, a supplier substitution nobody mentioned.
Temperature. Melt and pour temperatures judged by eye rather than measured.
Color, through settling within a run and through pigment lot variation between runs.
Fill weight, which drifts with pour temperature and with whoever is pouring.
Flavor, through addition temperature more than through dosing.
The reference set
Keep the first, middle and last tube of every run, labeled with the batch code, stored cool.
Compare a new batch against the reference from the approved one, at the same temperature, in the same light. Not against memory, which is generous, and not against the tube in your pocket, which has been warm for a month.
This is the cheapest quality system available in this craft and almost nobody runs it.
Controlling the inputs
Write the formula with supplier, grade and INCI name against each line, not just the percentage.
Write the process with actual numbers: melt temperature, hold, pour temperature, cooling method, second pour timing.
Record the lot of every material against every batch, so an odd batch can be traced to a drum rather than to a theory.
Checking a run
Weigh ten filled tubes and look at the spread, not just the average. A wide spread is a pouring problem and it is also a net weight problem.
Look along the capped tray for crooked labels, marked tops and short fills.
And wind three tubes fully up and down, because a mechanism fault affects whole lots and is invisible until somebody tries.