Recommendation for old cast iron tub

Hi there,

I have a cast iron tub. The surface is not smooth anymore--1/3 of it is rough. It catches dirt real easy because of this.

A week ago a friend of mine came, and opened up the wall to fix the leaking valve inside the tile wall.

The tub wasn't covered up well, so I'm not sure if the concrete/soldering flux that fell on the tub made it worse as he worked in the area (see pic).

Was the tub damaged while the concrete sat on it?



The tub surface is quite bad right now (quite rough in half of the surface). I wonder what's a good recommendation (try clean it again, refinish, or get a new tub).

It it's cast iron, I would scrub it good with Comet and rinse well before making any other decisions. A good cast iron tub is hard to damage.

The question I have, is the rough (porcelain?) surface. I have already cleaned it once (the pic is after 1st cleaning).

The area closer to the faucet is rough when I move my hand on it. The surface is not flat--it has slight ripples. I can see a few traces where it looks like the surface was once 'eaten up' by some liquid that flowed thru' before.

Perhaps it's safe to use cleaning agent w/ bleach?

A cast iron tub is coated with porcelain- I don't think you can hurt it with any common household cleaners. It can be scratched up a lot and the scratches will hold dirt and make it harder to clean. If you can't get it clean and the finish is not to your satisfaction, a replacement C.I. tub is the best option. No other type of tub will take the abuse of a quality C.I. one.

Refinishing is a possibility, but it is not perfect nor long-lasting.

Many years of use and cleansers can dull the finish of a porcelain coated CI tub...I can attest to that from my mother's which is dull. The cleansers today tend to be less harsh, but it's like using 400 grit sandpaper rather than 120grit. If there's some mortar bonded to the tub, you could try a white scrubby and some strong vinegar - the acid from the vinegar will help to disolve the cement in the mortar and help to remove it. But, the sand from the mortar may add to the scratching. Solder probably didn't do anything to it - porcelain is fired at over 1000-degrees, and solder is rarely much over 400 or so by the time it falls through the air onto the surface. Some of the ripples may just be from the CI mold, or from the original porcelain coating.

A family size tube of whitening toothpaste and a Mother's Powerball in a cordless drill. See if it will buff out.

The older tubs were not "acid resistant" so the smooth finish could be damaged by cleaning products over time. Once it is gone, there is no way to prevent "dirt" from accumulating in the rough finish that remains. Either replace the tub, or have a professional refinisher redo the tub's finish. It will NOT be as long lasting as a new tub would be, but might suffice for your purposes. Do NOT use a "rebath liner" type option, since that can lead to more problems than you have now.

I tried the following:

- soap scum remover (let it sit for 15 mins)
- hydrogen peroxide (let it sit for 15 mins)
- Rooto household lye crystals w/ water (a bit dangerous--would hurt chrome/brass piping?)
(let it sit for 1 hr)

Each helped somewhat. Hydrogen peroxide really brightened things up a bit. Still needed to scrub quite a bit afterward w/ soap scrum remover/lye crystals. There's still 30% left. More hard-work to do. Definitely looks better now. Might try toothpaste... .

Is soap scum remover too acidic on the tub?

When cleaning is finally done (it looks like it's possible now), I'll see how long it lasts before it traps dirt real bad again... . If goes bad real soon then really need to consider refinishing. Thx for the tip on the liner--won't try that as I heard some say it might trap water under the liner... .


Won't let any concrete/dirt fall on the tub a 2nd time for now...