backnuts for sink, basin, and bath wastes

What's wrong with plastic backnuts for wastes .I've never had any problem with them . Plastic backnuts for taps are a bone of contention tho'. Why do you need a spanner for waste backnuts? Just use your hands ..they don't neeed to be that tight and anyway,you always get one( backnut) with the waste when you buy it so I don't get why you are asking this .

Meant to say ..see my new reply to your Bath Waste topic

I thought they were frowned on here, but perhaps that's just tap backnuts rather than all plastic backnuts?

I was using a pair of pump pliers but they chew into the plastic where you grip them. I thought they had to be tight. I was afraid of them leaking if they were too loose.

I have a slight leak from the bottom of the banjo but all other joints are ok.

That's tap backnuts

Nope .Just hand tight should do .

Use more LSX. That should do the trick

You really don't need to tighten them up so hard that you need them made from brass.

The size is standard in that one of the 2 trap sizes always fit one of the

A good pair of water pump pliers set to their largest size should do a good job of tightening the back nut.

Note that some wastes will require some sort of thread sealant (tape, cord or resin) on the threads in the 'target' section to make a seal.