Hanging scented wood for the car

A dry stick of wood to hang from the rear-view mirror, emptied of the air inside its grain, with essential oil taking the air’s place. No gel, no alcohol, no plastic beads — only wood and oil, giving off scent slowly, at the pace of the grain itself.

Fig. 1. The scented stick and the path the essential oil takes. L, a, b: length, depth and height of the stick.

End grain — the two ends of the stick, where the tubes in the wood open.
Growth rings — each ring is one growing season of the tree.
Rays — bands of cells running along the radius, at right angles to the rings.
Vessels — large tubes that carried water in the living tree; after impregnation, they hold the oil.
Oil moves along the grain — inwards from both ends, many times faster than across it.
Cord hole — for hanging from the rear-view mirror.

An illustration. Photographs of the product will follow.

Why wood

Wood is a bundle of tubes. While the tree is alive, those tubes carry water from the roots to the leaves; once the wood is dry, they become hollow chambers full of air. In a light wood, that empty space makes up more than half the volume.

Fill the space with essential oil and the stick becomes a reservoir that needs no casing: the oil sits inside the grain, escapes only at the surface, and the wood lets it go a little at a time. The scent comes from the essential oil itself, not through a solvent or any other carrier.

Vacuum impregnation

The dry wood sits in a sealed vessel and the air is pumped out. Air inside the grain expands and escapes as bubbles.
The essential oil goes in while the vessel is still under vacuum, covering the sticks.
The valve is opened. Pressure in the vessel returns to atmospheric, and this is the moment the oil enters the wood: the pressure outside pushes it into the chambers the air has just left empty.

Simple soaking only reaches the outer layer, because the air trapped in the grain blocks the way. Drawing that air out first is how the wood-preservation industry has long carried liquids deep into timber. We use the same principle; the only difference is that our liquid is essential oil.

A vacuum has a price. Low pressure makes the lightest compounds in an essential oil evaporate faster — and those are exactly the compounds that make up the top notes. So we pull only as much vacuum as the wood needs to give up its air, keep the oil cool, and leave it under vacuum for as short a time as possible. The stick should smell like the bottle of oil it was made with; that is what we check in every batch.

Along the grain, across the grain

Oil travels along the grain many times more easily than across it, because it follows the very tubes the tree used to carry water. The two ends of the stick — the end grain, where those tubes open — are therefore where most of the oil goes in, and where most of the scent comes out. We cut each stick along the grain and leave both ends bare: no paint, no coating.

In the car

Hang the stick from the rear-view mirror with the cord supplied. Keep the cord short, so the wood does not block your view or swing against the glass.
Never lay the wood directly on the dashboard, a leather seat or any plastic surface. Essential oils, citrus oils above all, damage plastic, leather and paint.
Sun makes the scent stronger and shorter-lived. Hanging behind the windscreen, the stick takes the sun directly, and a car parked in the sun can pass 60 °C inside the cabin. That is the physics of evaporation, not a fault in the wood.
When the scent fades, refresh the ends. Put a few drops of the same essential oil on the end grain, wipe any excess oil from the sides, and leave it a few hours to soak in before hanging it again — so no oil drips onto the dashboard.
Keep away from children and pets. Not to be eaten or chewed. Essential oils are flammable — keep away from flames.

What we will publish

“Long-lasting fragrance” appears on almost every scented product, and is rarely followed by a number. We will not write that phrase until we have measured it. Every lot of scented wood will come with:

How much oil the wood took up, as a percentage of its weight — weighed before and after impregnation, next to sticks of the same wood that were only soaked, to show what the vacuum adds.
A scent-release curve. Sticks are kept at 40 °C and 60 °C and weighed every day for 60 days. The weight they lose is the scent they have given off.
A test on interior plastic. A stick is laid on a plastic panel at 70 °C for 72 hours; we record whether it leaves a mark, and photograph the result.
The essential oil lot used, with its GC/MS analysis published unedited and the allergens that must be declared.

This page will be updated with the numbers once the measurements are complete. Until then, it is not on sale.

Want to hear when it goes on sale? Get in touch.