While several coatings have been tested over the years, SurfaSil (Figure 6, now referred to as hydrocarbon soluble siliconizing fluid) is the most common coating used in a ratio of 1:10 SurfaSil: hexane because it provides long T 1 values. The thickness of the SurfaSil layer is about 0.3-0.4 μm. Once evenly coated and dried, the cell is then placed in an inert environment and a droplet of alkali metal (≈200 mg) is placed in the cell, which is then dispersed to create an even coating on the walls of the cells. One method for transferring the alkali metal into the cell is by distillation. In the distillation method, the cell is connected to a glass manifold equipped to hold both pressurized gas and vacuum, where an ampoule of alkali metal is connected. The manifold and cell are vacuumed, then the ampoule seal is broken and the alkali metal is moved into the cell using the flame of a gas torch. The cell is then filled with the desired gas mixture of nitrogen and noble gas. Care must be taken not to poison the cell at any stage of cell preparation (expose the cell to atmospheric air).