Last year I did a bit of renovation in my downstairs bog, including tiling the floor. The old sink waste was copper which was basically mortared into a hole in the concrete floor to connect to the drain. I put a stub of plastic pipe with a compression connector into the 'new' hole (ie through the tiles and the concrete) and sealed it around with silicone.
Now I've come back to this job after a pause (yes I know it's a while but there have been other things happening!) and I've found that the silicone fills the space around the pipe well, but didn't stick to the plastic. Clearly not ideal for the long term, or even the short term as I need the pipe to be firmly held to connect the sink outlet to it.
So....Does anyone have any bright ideas for making the silicone stick to the pipe? I'm guessing that the problem is that the pipe is too smooth and perhaps roughening it up a bit with some coarse sand paper might do the job, but I'm hoping there might be a chemical/glue or other approach I don't know about.
Cheers G