Author Options:


Hi everyone.  This is my very first Instructables experience - I've just found you guys.  I'm wanting to know if I could resurface my old cast iron enamel bath with concrete??  Would it stick???



3 years ago

EHHh.... so... i know of a way to do this, but it involves electricity, and it's probably not something you can easily do at home.

Basically, have you ever heard of Biorock (you can google this term)? it's the technology that they use to rebuild critically threatened corral reef in some parts of the world.
It's basically just running electrolysis on water full of calcium or magnesium ions. it forms a coating of calcium or magnesium carbonate on the surface of the cathode. If you use your iron frame bath tub as the cathode, it'd develop this same coating. The process gets a little weird when the calcium/magnesium concentration begins to drop off, and conduction becomes more difficult.
In places other then the ocean, this means you have to refresh the water's cation concentration with fresh calcium or magnesium.
I don't know if i'd encourage people to do this in their own homes, simply because the anode gives off pure oxygen and that's a fire hazard, but if you've ever been passingly interested in electrolysis, this might be an interesting adventure.

Do I want to know why you prefer concrete over enamel paint or acrylic paint?
There are special cosmetic tools to remove excess skin flakes, sounds easier than concrete...

Thanks for reading & getting back to me guys. Downunder35m - lol - you may not want to know, but I'll tell you anyway.... I stripped out the bathroom - old - never waterproofed - earthenware plumbing outside cracked too. I had tree roots under the bathtub (lead pipe bung & leaked water underneath for ever by the look of it) & hair roots under the tiles (which were falling off). Anyway, the tub had been trashed by house sitters (steelo or something). I got the idea to make my own step down into soaker style tub using besser bricks, render, waterproof, tile. I'm making a concrete vanity top, I just like coloured concrete & need a change. I had considered using an old fibreglass tub as a mould for the step down tub. My inquisitive mind just wondered if it was possible to do the inside of the tub & leave the "mould" there.

One thing you should consider is thermal effects.
A cast iron bath tub is bad enough to keep warm, with added concrete it will be a challenge.
Unless you fill with boiling water and wait till it reaches the right temp you will not stay in a concrete tub for long.

I would either replace the old tub with a nice and big acrylic version, they can sit flat on the floor with added support underneath.
Or as an alternative for good looks make it out wood, there was a topic on that not long ago.
Of course just concrete as mentioned in the video would work too, but I still prefer something that actually holds the temp of the water for a long time.

Yes you're right about the temperature. I had considered this to be honest. My old cast iron tub was awesome. I did used to fill it hot & hop in when the room was warm. Since reading your response I just had quick squizzi and apparently the lucite perspex acrylic tubs are the latest rage. I wouldn't have credited the acrylic tubs to be honest. I thought they were just paper thin? Must have improved somewhat. I have seen Decina tubs on Gumtree locally, the google wizard suggests their tubs are all made from the latest and greatest.

Hey thanks heaps for the response. I've got my thinking cap on again. I did consider putting in some jets, pump, water heater from a spa into the concrete tub. I may be biting off more than I can chew! However it's something I'm only ever going to do once, it's an equity raiser and I want to do it the best I can. I want to look into what the other 2 chaps recommended too. Sounds interesting.

cheers Mr Downunder35. What part of downunder r u in? I'm in Adelaide.

Melbourne area.
You might want to grab a catalogue from Reece or similar places to check some designs.
As long as you add support at the right hieght you can even put a big spa bath at floor level, but most houses don't allow this without digging a hole in the ground.
For that same reason one should check first how low the waste water drain pipes are.
Last thing you want is the water from the dishes coming up your bath tub...

You could also look into powder coating your tub.


Probably not.

Inside or outside the tub? You would have a better bet calling in one of the pros to refinish your tub or get an acrylic tub liner that fits. Those DIY porcelain refinishing kits don't fare too well and you are using some toxic chemicals for prep and tricky application. Were you thinking of making a 2-3 inch thick concrete pool liner for your tub? Concrete needs to cure around some form for a long long time. Think of it as wet mud that slides off of slick surfaces, especially vertical ones. You can have drier and chemically stickier concrete but you would still need the thickness for smooth finishing and strength. You would then have to seal if for water containment use too.

Hiya caitlinsdad

Inside the tub I was thinking. Just for something different. I do have an alternative. The thought just crossed my mind and I couldn't find info anywhere on the net to date.

Concrete shrinks as it cures and leaving the metal form outside will expand at contract at a different rate so it will eventually work loose since it is not tied in. You do lose interior space with that as a shell mold. The video will lead you to other cast in place bathtubs. Good luck.