When stock goes off-condition
Updated
A candle is not perishable in any dangerous sense and it does stop being the product you made.
Candles age
Fragrance is volatile. It leaves through the lid seam, and it degrades in the wax.
The surface continues to crystallize, so frosting develops over months.
And dye fades in light, which is why the candle in the shop window is a different color from the one in the box.
What changes
Throw drops. The first and most important. A year-old candle smells of noticeably less than a month-old one.
Appearance drifts. Frosting, and in a temperature-cycled stock room, wet spots appearing and reappearing.
Color fades, particularly blues and purples and particularly in daylight.
None of it is a safety question. All of it is a sale.
How long stock keeps
Realistically six to twelve months as a full-strength product, stored lidded, cool, dark and stable.
Beyond that the candle still burns perfectly and no longer represents your range.
Which is an argument against building a year of stock in one run, however good the efficiency looks.
What to do with it
Rotate: sell the oldest first, which needs date codes on the base rather than a memory of which shelf.
Discount honestly at a seconds table rather than shipping a weak candle to a wholesale account, where it becomes their opinion of your range.
And use frosted or wet-spotted stock at markets where you can explain it in a sentence, rather than online where you cannot.