Too hard
Updated
The mirror of the last page, and the one makers reach by over-correcting.
How it shows
Nothing comes off at normal pressure. The stick is glassy and may crack or crumble when wound up. Applied hard, it leaves a waxy film rather than a smooth layer.
A hard balm also shows a cleaner pour and a better-looking top, which is why it passes visual inspection and fails in the hand.
The causes
Too much wax, usually after fixing a softness complaint.
Carnauba above a few percent.
A high proportion of a hard butter such as cocoa or kokum with insufficient liquid oil.
And cold, which is not a formula fault but produces identical complaints between December and March.
The fix
Drop the wax a point or two, or move part of a hard wax to a softer one.
Add liquid oil, preferring one with slip.
Check the ratio against what you actually weighed rather than against the written formula. A hard batch is frequently an arithmetic error or a mis-set scale rather than a design problem, and that is worth eliminating before reformulating.
The winter version
Complaints that cluster in cold months on a formula that was fine all summer are an ambient problem. Do not reformulate on them without checking the dates.
Keep a reference tube of every approved formula. Warm the returned tube and the reference to the same room temperature and compare: if they match, the formula is unchanged and the customer is cold.