Silicone sealant - shelf life and failure mode
 

Hi all -

Fitted a stainless steel 'sit-on' kitchen sink onto a cheap B&Q base unit
yesterday. Instructions said to bed it on silicone sealant. I used a tube
of trade Evode window silicone, which had been around for years but
unopened. Tube says quick-skinning, high-adhesion, low-modulus, so it
seemed ideal.

I noticed at the time that there was no vinegary smell, and 24 hrs later the
surface hasn't skinned (in dry area, room temp). So I'm thinking now, was
it out-of-date and if so what does that mean? I'd always assumed that if
left for too long it would cure inside the tube, but this stuff seems to
have lost it's mojo.

Can some kind expert tell me what happens to silicone sealant if it's left
unused for too long?

TIA!

Silicone sealant - shelf life and failure mode
 

Steve Walker wrote:

Fitted a stainless steel 'sit-on' kitchen sink onto a cheap B&Q base unit
yesterday. Instructions said to bed it on silicone sealant. I used a tube
of trade Evode window silicone, which had been around for years but
unopened. Tube says quick-skinning, high-adhesion, low-modulus, so it
seemed ideal.

I noticed at the time that there was no vinegary smell, and 24 hrs later the
surface hasn't skinned (in dry area, room temp). So I'm thinking now, was
it out-of-date and if so what does that mean? I'd always assumed that if
left for too long it would cure inside the tube, but this stuff seems to
have lost it's mojo.

Can some kind expert tell me what happens to silicone sealant if it's left
unused for too long?


Old acetate-cure silicone will either not cure or take a very long time
to cure. If you've seen no skinning after 24 hours, I'd be very
surprised if you ever see any :-(


--
Grunff

Silicone sealant - shelf life and failure mode
 

Grunff wrote:
Steve Walker wrote:

Fitted a stainless steel 'sit-on' kitchen sink onto a cheap B&Q
base unit yesterday. Instructions said to bed it on silicone
sealant. I used a tube of trade Evode window silicone, which
had been around for years but unopened. Tube says
quick-skinning, high-adhesion, low-modulus, so it seemed ideal.

I noticed at the time that there was no vinegary smell, and 24
hrs later the surface hasn't skinned (in dry area, room temp).

Old acetate-cure silicone will either not cure or take a very
long time to cure. If you've seen no skinning after 24 hours, I'd
be very surprised if you ever see any :-(

Oh, bugger.... The pipework's all installed, and it'll be an evil job to
take it back off again (especially now it's 'buttered' with sticky sealant
round the edges). Never mind, it's only a 'bed' of 1-2mm so I'll scrape out
what I can and 'repoint' with new sealant. The mechanical fit is already
reinforced with small L brackets inside the base unit, so it's not going to
move around. Thank heaven I wasn't fitting a window frame or bath though!

Thanks for the info re sealant, Grunff.

Silicone sealant - shelf life and failure mode
 

On Mon, 07 Nov 2005 22:33:43 -0000, Steve Walker
wrote:

Can some kind expert tell me what happens to silicone sealant if it's
left
unused for too long?

I'll try and read up on it. Normally the problem with old silicone is that
it self catalyses and goes solid. However, to get back to the actual
problem, get the old stuff off with methylated spirits and paper towels or
rags, disposable is the only way to deal with the stuff. Make sure you get
to squeaky clean and redo with new stuff. Rather like epoxy glue, look
around for other jobs to do in the same session.

John Schmitt

--
Using Opera's revolutionary e-mail client: http://www.opera.com/mail/

Silicone sealant - shelf life and failure mode
 

John Schmitt wrote:
On Mon, 07 Nov 2005 22:33:43 -0000, Steve Walker
wrote:

Can some kind expert tell me what happens to silicone sealant if
it's left
unused for too long?

I'll try and read up on it. Normally the problem with old
silicone is that it self catalyses and goes solid.

Thanks John - I'd also assumed that if it was still runny, it was still OK.
Now scraping out the uncured sealant with matchsticks & rag - it's fun all
the way..... :o)

Silicone sealant - shelf life and failure mode
 

On Tue, 8 Nov 2005 10:57:35 -0000, Steve Walker wrote:

Now scraping out the uncured sealant

Best of luck, I found that it left a film that was impossible to
remove. I wonder if silicone remover would work?

--
Nigel M

Silicone sealant - shelf life and failure mode
 

Nigel Molesworth wrote:
On Tue, 8 Nov 2005 10:57:35 -0000, Steve Walker wrote:

Now scraping out the uncured sealant

Best of luck, I found that it left a film that was impossible to
remove.

Mmm, yep. Just like paint that never dries. Fortunately it's not an
exposed position or requiring mechanical strength - I can just bodge over
it. Very lucky it wasn't a door frame or similar.

I wonder if silicone remover would work?

Yeah, I'll try that. Meths just washed over it like water.... :o(

Cheers Nigel!

Silicone sealant - shelf life and failure mode
 

Yeah, I'll try that. Meths just washed over it like water.... :o(

Try acetone (nail varnish remover), but be careful to keep it away
from any plastic/acrylics