# Development of Effective Infrared Reflective Coatings
## 3 Results and Discussions
### Evaluation of Heat Reflection  
In order to demonstrate the influence of a coating on the substrate's temperature, samples were placed on racks outside and exposed to sun. The coated panels' temperatures were measured via heat camera (Table 7), and the temperature values were analyzed using the GUIDE PS610 instrument. The values described in Table 7 allow for a comparison of the effectiveness of coatings from the point of view of heat reflection efficiency. As the red-marked numbers show, coatings S84/CR28, S84/CR/Lacquer, and S84/A80, developed on white primer, showed the best heat reflective characteristics. Comparing the temperature values with those measured on traditional coating, the highest difference we achieved was **11.5**\({}^{\circ}\)C, which is a significant value. The temperature differences measured on the good samples were in the range of the accuracy of the device; in other words, their effectiveness as infrared reflective coatings is similar. The results obtained via different techniques (colorimetric, total solar reflectance, and infrared solar reflectance parameters; heat reflection values) showed that the best infrared \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Short Name of Coating** & **Primer** & **TSR \%** & **IR-SR \%** \\ \hline \multirow{2}{*}{traditional} & white & 7.2 & 6.3 \\  & black & 7.2 & 6.3 \\ \hline \multirow{2}{*}{L95/CR28} & white & 28.8 & 45.5 \\  & black & 21.4 & 31.6 \\ \hline \multirow{2}{*}{S84/CR28} & white & **48.2** & **76.6** \\  & black & 26.8 & 39.1 \\ \hline \multirow{2}{*}{TR RU/ZD} & white & 38.6 & 61.6 \\  & black & 24.9 & 36.9 \\ \hline \multirow{2}{*}{S84/CR28/Lacquer} & white & **47.7** & **75.9** \\  & black & 18.9 & 25.7 \\ \hline \multirow{2}{*}{PS/ZD} & white & 37.9 & 60.8 \\  & black & 19.7 & 27.8 \\ \hline \multirow{2}{*}{S84/A80} & white & 44.3 & 71.4 \\  & black & 21.0 & 30.6 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: The TSR and IR-SR values measured on different coatings. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Name of the Coating**} & \multirow{2}{*}{**Primer**} & \multicolumn{4}{c}{**Temperature [\({}^{\circ}\)C]**} \\ \cline{3-5}  & & **Max** & **Min** & **Average** \\ \hline \multirow{2}{*}{Traditional} & white & 64.5 & 61.7 & **60.0** \\  & black & 64.2 & 52.4 & **60.4** \\ \hline \multirow{2}{*}{L95/CR28} & white & 59.3 & 48.6 & 54.5 \\  & black & 61.5 & 51.6 & 57.1 \\ \hline \multirow{2}{*}{S84/CR28} & white & 52.2 & 44.3 & **48.5** \\  & black & 59.6 & 50.9 & 55.5 \\ \hline \multirow{2}{*}{TR RU/ZD} & white & 57.4 & 48.0 & 53.2 \\  & black & 61.4 & 51.7 & 57.3 \\ \hline \multirow{2}{*}{S84/CR28/Lacquer} & white & 54.2 & 45.2 & **49.8** \\  & black & 61.7 & 52.4 & 58.3 \\ \hline \multirow{2}{*}{PS/ZD} & white & 55.5 & 47.2 & 53.0 \\  & black & 61.0 & 51.7 & 57.6 \\ \hline \multirow{2}{*}{S84/A80} & white & 52.3 & 46.2 & **49.8** \\  & black & 59.4 & 51.4 & 56.0 \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Temperature values measured on coatings via heat camera. reflective coatings were developed on white primer, as they always showed higher infrared reflectance than those covered in black primer. The results obtained via the other different methods support this observation. Coatings with special pigments have better reflection in the wavelength range between 700 and 2500 nm than in the full spectrum (330-2500 nm), which contains the absorption of UV and visible light, too. Considering the composition of the best infrared reflective coating, it proved the importance of pigment concentration: a decrease in the concentration resulted in much better characteristics in the case of the S84/CR28 and S84/CR28/Lacquer coatings. This factor is important from the point of view of coating production: les pigments make the product more cost effective. We can draw another inference provided by these results: the infrared transparent coatings ranked first among the considered coatings.