Does silicone adheres better to sanded glass?

[alexmarto]

Hi,

I need to reinforce a second hand tank that a friend ofered me. It has three top braces that i want to remove, leaving just the one in the middle.
The two that i'll remove would be replaced by bracing the top perimeter of the tank and this is where my problem begins.
Because the tank is used, there is a fine coating of some kind of "calcareous" deposit in some places where i need to glue the reinforcement braces.
I can not remove this deposits no matter what i do. I've tried strong (dangerous) acid for days, razor blade and nothing worked.
I'm afraid that that silicone will not make a strong bond in those places so I thought that if i sand the glass in those places i could remove the deposits leaving just heavly scretched glass.

Do you think that silicone will adhere better or not worst than the usual way in sanded glass?

Thanks

manklit

 

[Anonymous]

Silicone does not stick better on sanded glass, otherwise, they would have rough the edge before gluing... but that is just induction logic, not based on any physical fact.

There is no way that a razor blade do nothing to the deposit, unless it is harder than steel!... It can't be calcareous, since pretty much all calcium mineral will dissolve under low pH condition, as least all those that come to my mind at this time.

If you must remove it by sand paper (that deposite must be harder than steel, but softer than sand paper), just make sure you clean the glass surface well so that no particle will come off and make the silicone less ahesive.

(ask your friend what did he/she do to that tank, since I am sure many coating-chemists are interested to find out how to do it)

 

[z rock]

Calcium deposits actually etch the surface off glass.If you used acids on it then you probably have it as clean as its going to get.
As well as silicon sticks to smooth glass it would probably grip like crazy to an etched surface.There's microscopic holes for it to get into.Just clean the seem with alcohol and apply some clamps or turn the tank on it's side and add weight.