What is the Wik™ surface?
Our Wik™ surface is a special texture used on D-NAiL® sapphire inserts and the new Quartz HALO™. It is designed to facilitate the spread of fluids via capillary action. This is the same physics behind why a sponge holds water, or how oil lamp wicks work, except in our dishes the fluid is only dispersed along the surface and not absorbed. Carb caps that provide vortexing airflow, such as the D-NAiL® Universal Carb Cap, also spread material around the dish by pushing it with air. The combination of a vortexing carb cap and the Wik™ surface work together to maximize material distribution in the dish.
Why would I want a nail with the Wik™ surface?
When you use a nail with the Wik™ surface, the increase in essential oil distribution across the surface directly corresponds with an increase in energy transfer, allowing your essential oil to absorb more heat from the dish in the same amount of time. This leads to a faster and more even vaporization.
The Wik™ surface also serves the same purpose as "seasoning" a nail. The current understanding why seasoning a nail works is that small bits of carbon are left behind, which act as vapor nucleation points to assist in boiling the oil. The Wik™ texture is naturally abundant with these nucleation points, so you always get the benefit of a seasoned nail, even when it is brand new or completely clean.
Heater/Dish Temperature chart for the D-NAiL® Quartz HALO™, the first nail to feature the Wik™ surface, available here.
Tell me more of the hard science!
We'd love to! Glad you asked.
There are multiple types of boiling: nucleate boiling, transition boiling, and film boiling. The type of boiling that occurs depends on the difference in temperature between a surfaces temperature and the liquid's boiling point. The common method of checking if a frying pan is hot enough by sprinkling a few drops of water on it is an example of this phenomenon. Seeing how the droplets behave shows what type of boiling is going on, and thus how hot the pan is. Besides temperature, other factors that influence what type of boiling occurs are; air/ambient pressure or — in the case of Wik™ — the texture of the surface.
Nucleate boiling is the typical boiling observed in a pot of water on the stove. Small pockets of liquid change phase into a vapor in the form of bubbles, which rise to the surface. This results in a mixing of the liquid, which helps to transfer heat evenly throughout it. The locations where this phase change is possible are called "nucleation points". Nucleate boiling is the type of boiling with maximum heat energy transfer and the fastest vaporization. Since high energy transfer and fast vaporization preserve more of the flavor of your essential oil, nucleate boiling is the ideal method of vaporization for our purposes.
If the surface is hot enough (past the critical heat flux), it enters transition boiling. This is when you see violent spitting and spattering as droplets boil away explosively. In this state, increasing the heater temperature actually decreases the rate of heat transfer due to vapor partially insulating against the hot surface, which is a bad thing for our purposes. Eventually, at a temperature called the Leidenfrost point of the material, we move into the final type of boiling.
Film boiling occurs if the surface temperature is past the Leidenfrost point which is dependent on material/surface combinations. Instead of forming bubbles, a thin cushion of vapor forms between the liquid and surface. To again use the frying pan example — on a pan ready for pancakes, this air cushion is why the water droplets dance around the inside of the pan. This vapor cushion acts as an insulator, so even though the pan is hotter it will take longer to vaporize the liquid. Heat transfer and speed of vaporization are lower than nucleate boiling, so for our purposes it is to be avoided.
The Wik™ surface is designed to keep your essential oil vaporizing via nucleate boiling. It has a very large number of nucleation points — enough to change the curve for your material. At high temperatures, the vapor cushion for film boiling cannot be formed, as the nucleation points channel the bubbles to release instead of forming a dome or cushion. At lower temperatures, the plentiful nucleation points allow nucleate boiling to continue when it would normally cross over into transition boiling. The rate of energy transfer is kept at or near maximum, resulting in a faster, more consistent vaporization with thicker vapor and no need to ever season your dish.
Below is a pair of charts to visually illustrate what is described above.