Discoloured silicone / caulk

[quantasm]

Hello,

I've just refitted my bathroom and 3 weeks ago I applied some clear Dow Corning 785 silicone around my new bath overflow and basin taps. After only 3 weeks it's turned a yellow/brown colour.

I thought Dow Corning was supposed to be one of the better brands so it was really a post to see if anyone has experienced anything similar or know how this could happen?

I've also been using the DC 785 white which seems fine where I've used it. Could it be the black rubber washers on the taps/overflow leaching into the silicone or perhaps a dodgy batch?

Any ideas are welcome

Thanks
Q

 

[HERTS P&D]

Dodgy batch would be my guess, take a picture and send it to Dow Corning and see what they say.

Andy

 

[Burnerman]

785 isn't suitable for contact with rubber mate - the plasticisers bleed out.
Don't ask me how I found this out....
John

 

[quantasm]

I've just been on the Dow Corning website and found this tucked away in a Q&A pdf

Dow Corning® Silicone Sealants Frequently Asked Questions

Q: Will cured silicone sealants yellow?
Most do not yellow. Some oxime sealants, which contain amines, will yellow and should not be used in places where the yellowing will be seen. Occasionally, other sealants can be discolored by hard coats used on plastics. Some rubbers have plasticizers that will leach out and discolor adjacent, light-colored sealants.

What can I use instead?

 

[Burnerman]

Only my technique, but I chuck out the rubber washers (I find they squash out of place anyway) and replace them with polythene washers, with a light layer of silicone.
These washers are available in packs of different diameters from B&Q etc.
They don't leak, and allow the tap to be tightened down just that little bit more to stop them moving.
John