Hi
I used the same tube of silicone in the bathroom and the ensuite. It had gone yellowish only in the bathroom. It's quite obvious where it meets the vertical silicone which was older (but didn't need replacing). Where the tiles meet the shower base it us yellow and the edges are starting to lift. The shower is about 4 years old but it is pretty messy where the tiles meet the base- very uneven gaps some quite large and some very small. I had my current builder silicon it after I removed the grout (it had never had silicone and the grout was falling out. Problem was that he wasn't very good at it plus it got all dirty when wet because the skylight was installed straight after and crap fell in it. Because of the uneven gaps there were still gaps between the tiles and the base. When I redid the silicone I went over his. It was about 8hrs later and it wasn't totally dry. I also used the quick dry silicone. The shower has only been used a handful of times in the 6 weeks since it was done.
So any suggestions as to why this has happened?
Cheers
Donna