"John B." wrote in message
...
On Fri, 13 Jan 2017 10:17:20 +1100, James
wrote:

On 13/01/17 08:33, Phil Lee wrote:


But in this case, there is already movement in the cup - all that's
needed is a little extra space for the movement of the cup in the
bracket shell to allow the corrosion to be ground down a bit finer by
working the joint back and forth.


I wonder whether a couple of hours soaking in a solution of CLR (Calcium
Lime Rust household cleaner) would help?

I had never come across CLR. How effective is it in removing heavy
lime deposit in pipes?

There used to be a product called Fernox DS9 for de scaling water pipes and
boilers.

There's also Brickclean used in construction for removing cement splashes
from the brick face. It contains detergent, so foaming can be a problem.