## 1 Introduction
The most significant difference between the hydrophobic and hydrophilic soot deposits was their grain size: a larger grain size of 50 nm for the hydrophobic deposits and a smaller grain size. The difference between the hydrophobic and hydrophilic soot deposits was due to the fact that the hydrophobic materials are not affected by the hydrophobic materials. \begin{table}
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**Author** & **Flame Deposition Process** & **Study Findings** & **Fuel * \\ \hline [PERSON] et al. & & & \\ [PERSON] et al. & & & \\ [PERSON] et al. 30 nm grain size for the hydrophilic deposits. The decrease in grain size may have been caused by increased rates of oxidation at the edge of the flame. [PERSON] et al. compared the hydrophobicity of carbon layers (C-layers) produced in co-flow Canola Methyl Ester (CME) and methane (CH\({}_{4}\)) air flames at different heights within the flame (Table 1). It was found that formation of the hydrophobic C-layers was highly dependent on flame structure, specifically the pyrolysis zone and the outer luminous zone [20]. Deposition within the pyrolysis zone would not produce hydrophobic soot, while deposition in the luminous zone guaranteed the deposition of hydrophobic soot. It was determined that the CME/air flames, due to being sootier and having a much smaller pyrolysis zone when compared to CH\({}_{4}\), are an excellent medium for the creation of hydrophobic C-layers. [PERSON] et al. created hydrophobic soot layers on a glass substrate using a candle and then cleverly modifying the layer with an MTCS coating [30]. The hydrophobicity of the flame-formed soot was not impacted by the MTCS layer, instead its durability was enhanced (Table 1): the MTCS coating improved the durability of the C-layer in high temperatures, corrosive liquids, and scouring via water droplets. Furthermore, upon completion of all durability tests, the deposited soot with the MTCS surface coating remained hydrophobic with only minor decreases in produced water contact angles. This illustrates the capability for flame deposition to be compatible with further enhancement by post-deposition processes. [PERSON] et al. was able to create hydrophobic surfaces using waste oil on fine and coarse river sand, showcasing the flexibility of the flame method to work on many different surfaces without using high-quality fuels [27]. When water droplets were placed on the coated river sand, the water was not absorbed, instead the droplets formed unique oblong shapes that followed the curvature of the sand (Table 1). Finally, [PERSON] et al. combusted rapeseed oil with air in a unique chimney burner to produce hydrophobic soot layers for anti-frosting. Air was introduced to the burner at three flow rates: 0.0052 m\({}^{3}\) min\({}^{-1}\); 0.0040 m\({}^{3}\) min\({}^{-1}\); and 0.0030 m\({}^{3}\) min\({}^{-1}\). It was found that at each air flow rate, 0.0052 m\({}^{3}\) min\({}^{-1}\); 0.0040 m\({}^{3}\) min\({}^{-1}\); and 0.0030 m\({}^{3}\) min\({}^{-1}\), frosting occurred at temperature of \(-9.8\)\({}^{\circ}\)C, \(-15\)\({}^{\circ}\)C, and \(-28\)\({}^{\circ}\)C, respectively (Table 1). The lowest air flow rate created soot with significantly improved anti-frosting performance that was much more durable than the other layers. Researchers attributed the performance of the soot layers to their surface morphologies. The layer formed at the highest air flow rate consisted of quasispherical aggregates that are known to be brittle, while the more durable layer formed at the lower air flow rate consisted of the more robust modified quasisquare-shaped islands [22]. Some initial flame studies into the formation of hydrophobic C-layers were exploratory in nature and showcased the effectiveness and capability of these flame-formed C-layers. We expanded upon that research, first by testing two fuels, a gaseous fuel (methane) and a vaporized biodiesel fuel made of Canola Methyl Ester, to form hydrophobic carbon films on solid substrates.