It stopped throwing scent

The reeds have clogged

Heavier fractions build up in the pores and the wick slows. Flipping them exposes fresh reed and helps for a while; replacing them fixes it. This is the most common cause and the easiest to explain to a customer.

The blend is too thick to climb

Capillary rise falls off quickly with viscosity. A blend that smelled right in a dish can fail entirely in a reed, and the symptom is a full bottle doing nothing at all.

Not enough reed is in the air

Throw comes from the exposed length, so a short reed in a tall bottle has very little surface working. Reed length and bottle height are a matched pair, not two independent choices.

The light notes have already left

Evaporative dispensing fractionates the blend, so top notes go first and the base lingers. A customer two weeks in is smelling a different part of your formula, and describing that up front turns a complaint into an expectation.

Room conditions matter more than people expect

Airflow, temperature and the size of the room all change the result, so the same bottle performs differently in a hallway and a bathroom. Worth one sentence in the instructions, because it accounts for a lot of otherwise puzzling feedback.

Test the format, not just the fragrance

Run the real bottle with the real reeds for a month before deciding the blend is right. The dish on the bench tells you about the oil and almost nothing about the product.

Set the expectation in the copy

Reeds are consumable, throw varies with the room, and the scent changes as the blend fractionates. All three are normal and all three read as faults to a customer who was not told. A sentence each turns the most common complaints in this category into understood behavior.

References