Remove "all" the lead?

[diy'r]

I am doing a diy 4-inch waste drain (toilet) lead bend replacement under a slab. So far I've removed the lead bend to leave ferrule, which I think is brass, connected into the cast iron hub.
I've torched the ferrule and scraped away most of the lead, then wiped it with a wet cloth to leave a smooth, thin, shiny surface of remaining lead coating the ferrule , but the actual brass does not show. My plan here is to even up the ferrule's outer edge and then attach a mission no-hub (or similar, like fernco), then assemble the rest of the drain with pvc leading up to the a new flange. The photos show my progress to this point.

All the discussions and Youtube guidance I've found has casually used the words "remove all the lead"when describing their steps with this type of project. My question is pretty simple. Is it really necessary to remove all the lead from the brass ferrule? If the remaining thin coat of lead is thin enough I would think it will be ok to just tighten the no-hub bands against it and that the very thin lead coating on the ferrule would yet make a strong enough surface for a seal against any possible leaks at the no-hub connection. But, this is the first such project I've ever done.

I would appreciate any information from this helpful site by participants that may have experience with this point or otherwise could give some fitting guidance.

 

[Breplum]

I've successfully done exactly what you have done many times and then used a variety of different-than-standard no-hub couplings. I carry every variety of transition coupling that have many I.D. options, amongst: Thin Wall to C.I., PL to C.I., etc

 

[Sponsor]

 

[Reach4]

My plan here is to even up the ferrule's outer edge and then attach a mission no-hub (or similar, like fernco), then assemble the rest of the drain with pvc leading up to the a new flange.

Surprisingly, the 2-worm-gear shielded couplings are not rated for underground. The unshielded Fernco flexible black rubber ones are. The 4-worm-gear shielded couplings are not rated for underground. I don't know why they don't rate the 2-worm-gear shielded couplings for underground.

Consider filling the space with sand.

Cast Iron Ptrap on remodel

Hi everyone. I’m located in South Florida. I’ve done a few tub conversion to shower stall before. Always ran into PVC plumbing. Have this one old tub/shower combo that was piped with cast iron pipes. Whole house is. House was built 1965. This ptrap here is not leaking, however the owner does...

terrylove.com

 

[diy'r]

Surprisingly, the 2-worm-gear shielded couplings are not rated for underground. The unshielded Fernco flexible black rubber ones are. The 4-worm-gear shielded couplings are not rated for underground. I don't know why they don't rate the 2-worm-gear shielded couplings for underground.

Consider filling the space with sand.

https://terrylove.cReacom/forums/index.php?threads/cast-iron-ptrap-on-remodel.106794/#post-761451

Reach4 and Breplum, thanks for your replies and for the tip on the right type of couplings. As for the remaining lead removal, I've considered using some acids that would dissolve all the remaining lead to leave a clean brass surface, (trying not also to to etch the brass surface any.) But I hesitate to deal with the acid fumes. It may be a no-brainer that I can just heat up the lead and leave as much as a thin coating of the lead left over the brass by wiping it with a wet cloth. But, like I mentioned, this is unexplored territory for me. Would you agree, or do you see any problems with that plan?

 

[Reach4]

Don't bother trying to remove the solder residue. Put the coupling onto what you have.

 

[diy'r]

Don't bother trying to remove the solder residue. Put the coupling onto what you have.

OK, Reach4. Thank you very much that definite answer from someone with the first-hand experience.