Getting glass really clean

[Mussels]

I'm stuck and looking for ideas, I've tried resealing an aquarium three times but it keeps leaking.
All the guides say use acetone or ethanol to remove all the old silicone residue but it doesn't work. I've used razor blades to remove as much as possible and it feels perfectly smooth but I can see there's something still there and the new silicone won't stick.
It's time for a nuclear option as the next idea is chucking it out. Any clever ideas out there? I'll try Brillo pads if necessary.

[mangocrazy]

Different 'grits' of Scotchbrite (green, then red, then grey (finest)) along with acetone or isopropyl alcohol? You could also try using some of those silicone eater concoctions to get the last residue of the old stuff off.

[Count Steer]

Different 'grits' of Scotchbrite (green, then red, then grey (finest)) along with acetone or isopropyl alcohol? You could also try using some of those silicone eater concoctions to get the last residue of the old stuff off.

Sort of related but isopropyl alcohol is what they use in the glazing world for cleaning glass before putting glazing bars on.

I've never found a satisfactory chemical remover for silicone though.

[David]

Turps followed by washing up liquid.

[Yorick]

All of the above. Maybe wet n dry paper as well ?

[Mr. Dazzle]

Silicone contamination is basically impossible to remove fully. That is why silicone is banned in many facilities/factories where it's important shit sticks. Even having silicone in an oven will put enough contamination into the air /surfaces of that oven to fuck up any subsequent bonding process. Lots and lots of companies will check you for silicone rubber watch straps, cause bracelets and stuff like that before letting you in.

Any abrasives typically just spread it about, with the added bonus that anything else you subsequently touch with the same abrasive also gets contaminated.

You're looking at even single atom layers remaining on the surface being a problem. Granted, you're not gluing the wings on an A350 here, but I'm not surprised you're struggling!

https://www.techsil.co.uk/media/wysiwyg ... _paper.pdf

If stuff ain't sticking (in any context) I can pretty much guarantee you it's cause things weren't clean i've lost count of the number of times people go on big investigation journeys only to discover that things were not clean. It's just my default response now "check you cleaned it enough, then ask me again later".

[Mussels]

Hmm, bitter sweet. I feel vindicated that I'm not a moron but disappointed because a new tank will cost a few hundred quid.
Thanks chaps, that has all been informative and helpful. I might give it one more try going further up the glass to maybe find some clean bits for it to stick to.
Each time it has lasted a few hours, I guess as the new silicone slowly loses it's grip. So it would work fine to keep rain out of somewhere but not under pressure.

[Count Steer]

Apparently there are primers available but they seem to be for porous material (seems odd to be putting it on porous things though), however it looks like some silicone may be better than others on glass eg

'What is the best window sealant? Our bestselling glazing sealant is Everbuild Silicone 825 LM. As a low modulus, neutral curing silicone sealant, this product offers exceptional adhesion and can be applied to most surfaces, including glass, metals, plastics and wood.'

I found some others that glazers seem to prefer but don't know what sort you are using.

[Mussels]

I need to use pure silicone as any additives are likely to be toxic. It was a popular brand for aquariums but I might switch and try a different one in case.
Edit: I used Bond It HA6
The smell makes that seem like acetic silicone which is designed to be quick curing, I'll try and find a standard set version instead.

[David]

Can you not turn the glass over/round?

[Mr. Dazzle]

Can you not turn the glass over/round?

I was gonna suggest maybe sacrificing 10mm off each panel (probably tempered glass and impossible to cut) but this works even better

[Mussels]

Can you not turn the glass over/round?

It is a good idea but the glass is still box shaped, I'm just trying to reseal it rather than rebuild it. It's also a complicated box with 11 different pieces to assemble.
Trimming it is no good as it's sized for the cabinet it's on and it has a hole in the bottom in a certain place to drain into the filter, that hole would also make reversing the bits difficult.

[Mr. Dazzle]

Could you run a comically oversized bead that reaches out onto virgin glass?

You may well have smooshed silicone out there with your previous attempts sadly. I might be worth getting so dedicated silicone cleaner as above.

[Count Steer]

I was wondering if you could somehow paint over the area where the silicone needs to seal (that may be contaminated with old silicone).

You can paint glassware in a way that's dishwasher safe (needs heat curing). Since it's OK for plates, glasses etc it should be low toxicity!

eg https://www.instructables.com/How-to- ... -Dishes/

[Mr. Dazzle]

But the paint won't stick either

[Count Steer]

But the paint won't stick either

Well, you can paint some silicone. Got to be worth a try before trashing the lot.

[Cousin Jack]

If I recall my chemistry correctly, we used hydrofluoric acid to get glass really REALLY clean. Not sure if it works on silicone.

WARNING. It is evil stuff. Read the label carefully!

[Count Steer]

If I recall my chemistry correctly, we used hydrofluoric acid to get glass really REALLY clean. Not sure if it works on silicone.

WARNING. It is evil stuff. Read the label carefully!

Clean? It'll do that all right. It dissolves/etches it and it's v nasty stuff*. However, it's kept in plastic bottles (obvs ) so it probably won't touch the silicone.

*The burn isn't the only problem, it gives you systemic fluoride ion poisoning.

[Cousin Jack]

If I recall my chemistry correctly, we used hydrofluoric acid to get glass really REALLY clean. Not sure if it works on silicone.

WARNING. It is evil stuff. Read the label carefully!

Clean? It'll do that all right. It dissolves/etches it and it's v nasty stuff*. However, it's kept in plastic bottles (obvs ) so it probably won't touch the silicone.

*The burn isn't the only problem, it gives you systemic fluoride ion poisoning.

That will explain why it was always a fume cupboard job. And if it doesn't eat plastic it is probably not worth the risk.

[Mr. Dazzle]

Hydrofluoric acid dissolves bone more readily than skin, it'll also permeate flesh.

Think about the implications of that

Fun fact - the combustion of modern fluoropolymers (as found in seals, hoses etc) can generate hydrofluoric acid. So if your bike or car catches fire do not breath in the fumes!