## 3 Results  
### Reflectance Values at a Wavelength of 335-380 nm  
Table 1 presents selected descriptive statistics of the reflectance at a wavelength of 335-380 nm. In assessing the differences in reflectance values at various time points (before oil application, after 20 min, and after 60 min), there was no statistically significant difference (\(p=0.4443\)) between particular time points for the reflectance at a wavelength of 335-380 nm after the application of Oil A. The results of repeated tests (Table 2) confirm the lack of differences at all time points of the reflectance assessment at a wavelength of 335-380 nm after the use of Oil A. In the assessment of differences in reflectance values at subsequent time points (before oil application, after 20 min, and after 60 min), a statistically significant difference (\(p=0.0348\)) was found between particular time points for the reflectance at a wavelength of 335-380 nm after the application of Oil B. Moreover, it was found that at a wavelength of 335-380 nm after the application of Oil B (Table 2), the reflectance value after 60 min of exposure was statistically significantly higher compared with the value before and after 20 min of exposure, while the reflectance value after 120 min of exposure was statistically significantly lower compared with the value after 60 min of exposure. In the assessment of differences in reflectance values at subsequent time points (before oil application, after 20 min, and after 60 min), there was no statistically significant difference (\(p=0.1779\)) between particular time points for the reflectance at a wavelength of 335-380 nm after the application of Oil C.  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Wavelength:** & & & & & & & & \\
**335-380 nm** & **Variable** & **Mean** & **Median** & **Min. ** & **Max. ** & **Q 25\%** & **Q 75\%** & **Standard** & **Shapiro-Wilk** \\ \hline Oil A before & A\_0 & 0.186 & 0.180 & 0.118 & 0.265 & 0.156 & 0.223 & 0.044 & \(p\) = 0.2202 \\ \hline Oil A after 20 min. & A\_20\_min & 0.195 & 0.186 & 0.130 & 0.306 & 0.162 & 0.222 & 0.047 & \(p\) = 0.2435 \\ \hline Oil A after 60 min. & A\_60\_min & 0.231 & 0.201 & 0.121 & 0.549 & 0.166 & 0.240 & 0.113 & \(p\) < 0.0001 \\ \hline Oil A after 120 min. & A\_120\_min & 0.255 & 0.184 & 0.092 & 0.617 & 0.142 & 0.283 & 0.167 & \(p\) = 0.0004 \\ \hline Oil B before & B\_0 & 0.194 & 0.185 & 0.111 & 0.299 & 0.168 & 0.207 & 0.047 & \(p\) = 0.0865 \\ \hline Oil B after 20 min. & B\_20\_min & 0.203 & 0.196 & 0.108 & 0.389 & 0.164 & 0.224 & 0.059 & \(p\) = 0.0221 \\ \hline Oil B after 60 min. & B\_60\_min & 0.253 & 0.221 & 0.125 & 0.597 & 0.176 & 0.264 & 0.122 & \(p\) = 0.0003 \\ \hline Oil B after 120 min. & B\_120\_min & 0.276 & 0.205 & 0.112 & 0.598 & 0.153 & 0.383 & 0.166 & \(p\) = 0.0004 \\ \hline Oil C before & C\_0 & 0.179 & 0.174 & 0.119 & 0.252 & 0.147 & 0.208 & 0.038 & \(p\) = 0.7732 \\ \hline Oil C after 20 min. & C\_20\_min & 0.191 & 0.186 & 0.104 & 0.253 & 0.167 & 0.228 & 0.039 & \(p\) = 0.7352 \\ \hline Oil C after 60 min. & C\_60\_min & 0.231 & 0.196 & 0.122 & 0.511 & 0.162 & 0.252 & 0.113 & \(p\) = 0.0006 \\ \hline Oil C after 120 min. & C\_120\_min & 0.257 & 0.184 & 0.094 & 0.553 & 0.148 & 0.376 & 0.155 & \(p\) = 0.0015 \\ \hline Oil D before & D\_0 & 0.188 & 0.185 & 0.107 & 0.297 & 0.158 & 0.223 & 0.052 & \(p\) = 0.8826 \\ \hline Oil D after 20 min. & D\_20\_min & 0.202 & 0.198 & 0.121 & 0.299 & 0.176 & 0.234 & 0.046 & \(p\) = 0.9195 \\ \hline Oil D after 60 min. & D\_60\_min & 0.237 & 0.214 & 0.097 & 0.599 & 0.150 & 0.259 & 0.128 & \(p\) = 0.0008 \\ \hline Oil D after 120 min. & D\_120\_However, it was found that at a wavelength of 335-380 nm after the application of Oil C (Table 2), the reflectance value after 120 min of exposure was statistically significantly higher compared with the value right before exposure.