I recently fitted a new cast stone based shower .... and as usual sealed
with "Dow Corning 785 Sanitary acetoxy silicone"

The shower is fitted in an alcove lined with Respatex sheets, on several
other showers still great after more than 10 year.

However - after less than 6 months the silicone has peeled off where it
was attached to Respatex ... still stuck to shower tray.
It is a clean line so looks like an adhesion problem.

There is slight shower movement, (less than 2mm) no more than you would
expect.

Shower tray is bedded on screed, ontop on a 4x2 frame which supports a
25mm thick ply base.
No movement in frame, tray must just lift up off bedding slightly when
not loaded. (did load up with bags of cement while sealing to ensure
well seated) Same method used on other jobs.


I will cut out the sealant where it has 'de-adhered' .... clean as
before with meths.

Obviously doubtful of using Dow 785 again, anybody know of a
particularly good Low-Modulus Sealant which contains a fungicide.

Or is this as good as any .. and just try again ... maybe leaving in a
wider bead this time. (previoulsy only about 5-7mmmm)

On Sun, 16 Nov 2014 14:55:54 +0000, rick wrote:

[...]

I'd be interested in an answer to this, too - and recommendations for
kitchen worktop sealants as well.

In message , rick
writes
I recently fitted a new cast stone based shower .... and as usual
sealed with "Dow Corning 785 Sanitary acetoxy silicone"

The shower is fitted in an alcove lined with Respatex sheets, on
several other showers still great after more than 10 year.

However - after less than 6 months the silicone has peeled off where
it was attached to Respatex ... still stuck to shower tray.
It is a clean line so looks like an adhesion problem.

There is slight shower movement, (less than 2mm) no more than you would
expect.

Shower tray is bedded on screed, ontop on a 4x2 frame which supports a
25mm thick ply base.
No movement in frame, tray must just lift up off bedding slightly when
not loaded. (did load up with bags of cement while sealing to ensure
well seated) Same method used on other jobs.


I will cut out the sealant where it has 'de-adhered' .... clean as
before with meths.

Obviously doubtful of using Dow 785 again, anybody know of a
particularly good Low-Modulus Sealant which contains a fungicide.

Or is this as good as any .. and just try again ... maybe leaving in a
wider bead this time. (previoulsy only about 5-7mmmm)


I used this stuff when fitting my bathroom out about 8 or 9 years ago.
I'm particularly impressed by the fungicidal properties as there isn't a
trace of mould yet.

http://www.everbuild.co.uk/sealants/...l/foreverwhite

--
Paul Giverin

My Photos:- www.giverin.co.uk

On 16/11/2014 16:11, Paul Giverin wrote:


I used this stuff when fitting my bathroom out about 8 or 9 years ago.
I'm particularly impressed by the fungicidal properties as there isn't a
trace of mould yet.

http://www.everbuild.co.uk/sealants/...l/foreverwhite


Just looked up spec .. does seem a Low Modulus anti-fungal silicone, and
on-sale in local Tool Station ... so may try that.

On 16/11/14 14:55, rick wrote:

I had a strip fail behind the basin - cannot recall if it was Dow or
Mapei...

I know what won't fail:

http://www.screwfix.com/p/geocel-the...te-290ml/72264

However it is a little matt in finished (I think it may be the so called
MS Polymer sealants some folk talk of, but I'm not certain).

I'm going to use it to re-do mine - and possibly run a thin bead of
white silicone over the top to get a smooth finish. I fthe silicone
fails, it won't do much harm...

Obviously doubtful of using Dow 785 again, anybody know of a
particularly good Low-Modulus Sealant which contains a fungicide.

Or is this as good as any .. and just try again ... maybe leaving in a
wider bead this time. (previoulsy only about 5-7mmmm)