[Ed]

did you clean the glass before applying the glue??

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Ed

 

[Ed]

If there was any transfer of oils (any kind including from hands) then there can be interference with the ability of the glue to adhere to the glass. This is why a lot of those kinds of glues suggest cleaning the glass with alcohol before applying the glue.

It can also depend on what kind of material your trying to glue to the glass for example, if your using lexan or plexiglass, silicone isn't your bond of choice since it doesn't adhere well to those materials and with gorilla glue, you can have the plastic "melt" into the glue changing the composition of the glue which affects adherence.

If your gluing glass to glass (and some other materials) then you want silicone. If your using other materials to glass your going to have to tailor your choices to the specific materials.

As for other safe silicones, you can get them from a number of sites that cater to aquarists (in the big tubes not the little ones that are expensive...)

some comments

Ed