as mentioned before briefly i fitted a new monobloc tap in my bathroom, using flexy connectors 12mm to 15mm pipe. i used the fibre washers supplied which made the seal. But I have read a bit of silicone/compound around the fibre washer helps make an even better watertight seal. What's the best type of putty/compound to use for taps/wastes, etc? i heard plumbers blue is good but have never seen it !!?? in future if it makes the joint/seal even more watertight then i'll get some!!