weeping solvent weld joint

[Iankkk]

Hi,
I have a weeping solvent weld joint on my bathroom sink. What's the best way to seal it please?

 

[Chuck]

The photo looks to me like someone used push-fit pipe for the vertical waste pipe with a solvent weld fitting. To confirm, measure the diameter of the waste pipe. Callipers are best but if you don't have them... Cut a piece of thread that exactly wraps twice around the pipe, then measure the length to get twice the circumference in millimetres. Divide this value by 6.28 to get the pipe diameter in mm.