Silicone sealant woes

[pilsbury]

Just wondering if anyone has advice on silicone sealant not sticking to UPVC window frames.

My mums conservatory is fairly old and last year I replaced the internal silicone sealant in the corners where frames meet, but twice now it has peeled away. Used 2 different types, a no nonsense cheapo and a more premium type. Ensured area was squeaky clean before applying.

Never had an issue with silicone before. Can’t see why there is this issue. Any advice on the stickiest silicone known to humanity?

 

[Nige F]

You need a Neutral Curing silicone. IF one smells of vinegar ( acetic acid ) it's the wrong one and won't work.

 

[noseall]

Just wondering if anyone has advice on silicone sealant not sticking to UPVC window frames.

My mums conservatory is fairly old and last year I replaced the internal silicone sealant in the corners where frames meet, but twice now it has peeled away. Used 2 different types, a no nonsense cheapo and a more premium type. Ensured area was squeaky clean before applying.

Never had an issue with silicone before. Can’t see why there is this issue. Any advice on the stickiest silicone known to humanity?

Soudal neutral cure. Don't be mean with the bead.

 

[pilsbury]

Right. I shall try that. What’s the reasoning behind that just for interest?

 

[noseall]

Right. I shall try that. What’s the reasoning behind that just for interest?

When ever I see window fitters caulk a joint, they usually tape the edges to prevent the silicone being squeezed down to nowt as well as give it a nice edge. The bead itself always seems reassuringly chunky too.

 

[^woody^]

Should be low modulus too.

 

[23vc]

When ever I see window fitters caulk a joint, they usually tape the edges to prevent the silicone being squeezed down to nowt as well as give it a nice edge. The bead itself always seems reassuringly chunky too.

Guessing they’re only taping the frame not any brickwork? I’ve always found you’ve got one chance against brickwork and it’s your first pass with a large cut nozzle. Any tooling needed after that and it goes pear shaped…guess once you’ve done a few hundred you get a steady hand…

 

[noseall]

Guessing they’re only taping the frame not any brickwork? I’ve always found you’ve got one chance against brickwork and it’s your first pass with a large cut nozzle. Any tooling needed after that and it goes pear shaped…guess once you’ve done a few hundred you get a steady hand…

Yeah, they always seem to cut a decent size nozzle but pump out very little excess. And that is the secret. That you are literally only tooling what you have pumped out of the cartridge. I like the way they finish corners - plenty of spit, whilst gently dabbing with the finger tip. No dragging here.

 

[noseall]

Should be low modulus too.

Agree low mod.

 

[^woody^]

A wide nozzle gives the 3-5mm cover either side of the [5mm?] gap, plus it won't wander so much into every little crevice in the reveal so it's easier to get a nice straight edge.

I don't ever recall seeking window fitters tape up though.

 

[Wayners]

Stuff in tubes.. Skill builder.. On youtube will cover all you need to know about mastics

 

[pilsbury]

Cheers chaps. Natural curing low modulus silicone it is. I’ll be pretty practiced now, having done this same job before….. admittedly wrong, but now I know!

 

[noseall]

A wide nozzle gives the 3-5mm cover either side of the [5mm?] gap, plus it won't wander so much into every little crevice in the reveal so it's easier to get a nice straight edge.

I don't ever recall seeking window fitters tape up though.

I’m sure it’s with the darker silicone colours so that the bead does not thin out to opaque and look unsightly.

 

[^woody^]

Cheers chaps. Natural curing low modulus silicone it is. I’ll be pretty practiced now, having done this same job before….. admittedly wrong, but now I know!

Don't forget a little cup of soapy water.

And whether you push or pull the gun is one for it's own thread.

 

[23vc]

No pressure. Done it yet?