# Why did I get these inconsistent experimental results in silanization?

I used a 50% wt mixture of Tetraethylorthosilicate + Kerosene for silanization of some glass plates with different treatment times (from 1 sec to 35 sec). However, the contact angle(CA) that I got does not seem consistent as it does not always increase as I increase the treatment time (when treatment time increases, the CA fluctuates).

What might be the reason? and whether I should change the method or the solution(s)?

P.S. I cleaned the glass with acetone in a sonicator. Then I put the glass into solution and after specific time put it into water to clean the solution from surface and then clean the remaining oil (from kerosene) by rubbing a napkin to the glass plate. Then I measured the CA.

• In theory there should be a correlation, but tetraethoxysilane (TEOS) is not a good chemical for silanization, as the ethoxy group can easily hydrate leaving you with a hydrophilic $\ce{Si}-\ce{O}-\ce{H}$ surface. I did assume everything else you did was the same, but factors such as humidity and exposure time to air can affect results due the the nature of TEOS – A.K. Dec 26 '15 at 4:39