Table 1: The sol-gel formulation using N-propanol as solvent.

Sample 0N 20N 40N 50N 60N 80N 90N N-Propanol 0 20 40 50 60 80 90 Methyl trimethoxy silane 100 80 60 50 40 20 10 Appearance Cracking Cracking Clear Clear Hazy Hazy Hazy