Best performing Low Modulus Silicone (bathroom)

[rick]

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)

[Cursitor Doom]

[...]

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

[Paul Giverin]

In message , rick writes

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.

[rick]

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

[Tim Watts]

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

I know what won't fail:

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...