Can anyone suggest measures to remediate exterior tub drain rust?

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Theo N.

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Greetings to the group:

This post seeks info on removing drain rust beneath a 1962-era cast iron tub before resurfacing.

I inspected the bottom of my tub, from the crawlspace. Some fresh-looking rust is emerging from between the shoe gasket and the tub bottom. It has spread to about 1/4 inch beyond the gasket, in all directions. The drain assembly is brass.

My sense is to disassemble the drain, remove rust with naval jelly, sand surface a bit, and then prime and paint. I can work in the crawl, and have cut an access panel to reach tub back.

Can anyone suggest steps for rust removal? How about for steps to treat the metal to prevent rust before i put the drain back together? Any comments or criticism would be stellar

EDIT: Thanks for the reply (to answer your ?, I don't know the condition of the tub interior because the "flipper" from whom we purchased the house this year had the tub resurfaced just about 10 months ago, and the new surface is starting to peel--we're irritated as all get out, but have no recourse).

Here, for all, are some pictures of the rust that I am trying to remove, in the area at which I'm seeking guidance here. Took these this morning from the crawlspace:

The image of "east side" shows the area of heaviest rust.

Image of "west side" shows much less rust, in a spotted pattern. Could this spell trouble?

The image "overflow side" shows that side of the tub, just for completeness.

Again, if anyone can offer guidance on steps to remove this rust, and steps to take to prevent recurrence, I would really appreciate your views and/or criticisms.
 

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Jadnashua

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Is the interior of the tub in good shape? Most people's experience with interior tub resurfacing is maybe about 5-years. Unless you remove the thing, shot blast it clean to the metal and have a way to reapply a good baked enamel finish, the epoxies work, but not anywhere near as long as an original finish.
 

Theo N.

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Jadnashua: thanks for the reply. We don't really know the interior condition, for reasons stated in connection with the pictures. I included a pic of the tub front's exterior, if that helps suggest inferences as to interior. Our decision to refinish the tub in situ is as much economics and timing as anything else. My hope is to get a good result for at least 5 years, but I define "good result" to include a non-rusting drain along with a sound epoxy application.
 

Jadnashua

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I just do not have enough direct experience with refinishing a tub. You can search this forum and see some other's results...generally, not great. My father tried it with one company, didn't like the result, and ended up tearing it out and replacing. The skill of the installer and their choice of products will make huge differences in how well it holds up. But, again, it will never be as robust as a new CI tub.
 

Terry

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It sure looks like the tub drain has been leaking onto the floor joist there.
I would not worry about rust on the bottom side of a cast tub. I would be more concerned about the drain assembly.

Ten months on the reglaze, or repaint? Yep, I prefer just pulling the tubs and starting over.
 

Theo N.

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Here is a short post after repairing my leaky tub drain.

I discovered the drain hole opening was (most likely) created for a 2" drain, but the existing assembly was only 1 1/2". Thus, I hunted for and found an oversize Kohler 2" drain shoe + strainer at one of our local vintage hardware stores (Hippo Hardware, Portland OR).

The incremental diameter increase is hard to see from the pics, but the new shoe is a little wider relative to the gasket, and the new (to me) Kohler strainer is a *lot* wider than the former strainer. Overall the width increase above, though, and below the tub mattered a lot. This wider "pancake" of apparatus seems much sounder in the drain hole. Three months have passed, and the seal appears to have lasted.

I lightly sanded & primed before assembling the drain, and afterwards cleaned up a little bit of rust that my earlier efforts failed to reach. Very little room to reach behind the drain opening, and my final coat of Rust Oleum went on by hand, after reinstalling the drain pipes, so the paint application looks sloppy (alas).

But, I think the sequence of 1) preparing the drain opening surfaces; and 2) upsizing the drain shoe, has extended the life of the tub (at least a few years) for the cost of parts. If in the end we must pull the tub, it'll sting less.
 

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hj

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What you did was "busy work", but probably had absolutely no effect on the lifetime of the tub. Even the rust you showed was cosmetic and had more to do with how the old drain was installed rather than sealing a new one.
 
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