I have some 2mm glass beads and I'm doing silanization on them. For doing that, I have a small bottle that I fill 1/3 with glass beads and then pour silan solution on them and shake well. However, after 60 min that I drain the solution from bottle and as soon as I wash the beads with water, the beads are covered with a white greasy product which is hardly removed by water and finally I wash it by acetone to become transparent again.

Is this a correct method of silanization (and washing the products) to achieve the maximum hydrophobicity effect of silan or I should revise the method?


Sol-gel preparation techniques have many variations. The contact time -beads to the solution - determines thickness of the sol-gel layer. Here you can try to shorten the dipping (coating) time. Glass is usually dried at 60°C for 30 mins and then "cured" at 500 - 550°C form 5 s up to 2 hours. I would suggest to find out an article and follow its preparation method.

  • $\begingroup$ 1) Is this sol-gel layer strong enough or it can be removed by rubbing a napkin on the glass surface? 2) Can cure time change the contact angle as well (remarkably), or it just thickens the layer? Thanks $\endgroup$ – vorujak Jan 4 '16 at 12:57
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    $\begingroup$ After high temperature heating, it is hard to remove this layer. Contact angle is affected by all the parameters. I would suggest to contact a person who has practical experiences. check solgel.com $\endgroup$ – Jaroslav Kotowski Jan 4 '16 at 13:41

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