Sweating and beading
Updated
On this page5
Small droplets of oil on the surface of the stick, or a greasy film inside the cap.
Droplets on the surface
The liquid oil has separated out of the wax matrix and migrated to the surface. On a tube it shows as beading on the exposed top; in a pot as a slick.
Unlike bloom it is genuinely a formula fault rather than a temperature history, and it will get worse.
Why the oil leaves
Too much liquid oil for the wax. The structure cannot hold it and the excess weeps out.
The wrong wax for the oil. Castor in particular is poorly held by some wax systems.
Heat. A formula that is stable at 20 C can sweat at 35 C, which is a pocket.
Cooling too fast, occasionally: a sharp chill can contract the stick and squeeze oil out. Which sits directly against the advice for graining, and is why both need testing rather than a rule.
The fixes
Raise the wax by a few percent and retest. It is the first move and usually the answer.
Add a small amount of a harder wax rather than more of the same, which lifts the melting point without adding much drag.
Reduce castor, or balance it with a less mobile oil.
And test at the temperature the product will actually see, which for a lip balm is body heat.
Distinguishing it from bloom
Bloom is dry, white and powdery and rubs away. Sweating is wet, clear and greasy and comes back.
Worth telling apart before you change anything, because the fixes point in opposite directions: bloom wants faster cooling, sweating usually wants more wax.