Home maintenance question - rust beneath caulk in tub

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Cunobelinus
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Home maintenance question - rust beneath caulk in tub

Post by Cunobelinus » Thu Jul 19, 2018 5:29 pm

Aloha,

Our caulk in the shower tub started "rusting." I removed the caulk this morning and found that it's bare metal beneath the caulk, and on the seam on the showerhead/spout side, it's bare metal with a helpful coat of rust. I'm looking for a good way to move forward with this that does not involve replacing the bath tub. If at all possible, I'm looking to do this myself.

I'm looking through home repair/maintenance websites and DIY websites too, but I'm continually impressed by the wealth of knowledge that the Bogleheads possess. So I figured I'd ask here.

I think a good way forward is to dry the rusty area out, remove the rust (CLR?), try to put down some enamel with an enamel repair kit, then recaulk it. I don't know how I'm going to remove the rust or put down enamel because it's a very tight tolerance -- I can barely slip a paper towel into it to try to dry it.

Anyone have any experience or recommendations with this?

This website doesn't appear to provide a solid way forward, but one person states a rust converter may be useful.
https://terrylove.com/forums/index.php? ... tub.23553/

Some more detail: this house was a rental for about 20 years, and we're periodically finding out just how "handy" the handyman was who "fixed up" the place before the previous owners sold it to us. In the tub alone, I found out a few months back that the overflow connection wasn't actually connected to anything.. it was just an open hole to outside of the tub beneath the spout. I only looked into it because I heard dripping from behind the tub one day. Out of sight, out of mind. Due to a great stroke of luck, there wasn't any mold because apparently the tub's bottom is open to the bottom of the house, so it was continuously vented. Apparently that isn't too uncommon out here.

2comma
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Re: Home maintenance question - rust beneath caulk in tub

Post by 2comma » Thu Jul 19, 2018 5:59 pm

Take a look at POR-15. If you get any loose stuff off it will definately stick to rust and protect it. It can be painted over but within a certain time period and only with certain paints so not sure your enamal repair kit is compatable. Just an idea to look into. You know what they say, "rust never sleeps" so you may be fighting a rear guard action on this one. Good luck!
If I am stupid I will pay.

Yooper
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Location: Nothern Michigan

Re: Home maintenance question - rust beneath caulk in tub

Post by Yooper » Thu Jul 19, 2018 7:34 pm

I've had good luck with Ospho (google it). Used it on a utility trailer which sits outside all the time and so far so good. I did minimal "prep" before applying it, and then painted over after. I'd dry it out, get rid of any rust as best you can (given the tight tolerances), spray in a healthy dose of Ospho (it's caustic so wear gloves and eye protection), and then seal it up. I'd even try to dose it with some Rustolium, if you can get it in there, before sealing.

Cunobelinus
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Re: Home maintenance question - rust beneath caulk in tub

Post by Cunobelinus » Thu Jul 19, 2018 7:49 pm

I just looked into Ospho, but I can't seem to find it anywhere. Neither Home Depot nor Lowes carries it. Maybe a marine equipment or boating store?

Thanks for the feedback. I'm leaning towards using a rust converter. I just have to see if I can put an enamel on top of that. I swear my googling skills were better in my younger years -- I just can't seem to find useful information anymore.

Yooper
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Re: Home maintenance question - rust beneath caulk in tub

Post by Yooper » Thu Jul 19, 2018 7:51 pm


Cunobelinus
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Re: Home maintenance question - rust beneath caulk in tub

Post by Cunobelinus » Thu Jul 19, 2018 8:01 pm

Sure, Amazon would be easy; however, Amazon doesn't ship a lot of stuff to Hawaii. Something or other about shipping costs or that we haven't been a state long enough..

This is one of the many items that does not ship to Hawaii. Two-day shipping also can take up to two-weeks, if it's even offered.. hence my desire to find it in a local shop.

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Sandtrap
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Re: Home maintenance question - rust beneath caulk in tub

Post by Sandtrap » Thu Jul 19, 2018 8:26 pm

Cunobelinus wrote:
Thu Jul 19, 2018 5:29 pm
Aloha,

Our caulk in the shower tub started "rusting." I removed the caulk this morning and found that it's bare metal beneath the caulk, and on the seam on the showerhead/spout side, it's bare metal with a helpful coat of rust. I'm looking for a good way to move forward with this that does not involve replacing the bath tub. If at all possible, I'm looking to do this myself.

I'm looking through home repair/maintenance websites and DIY websites too, but I'm continually impressed by the wealth of knowledge that the Bogleheads possess. So I figured I'd ask here.

I think a good way forward is to dry the rusty area out, remove the rust (CLR?), try to put down some enamel with an enamel repair kit, then recaulk it. I don't know how I'm going to remove the rust or put down enamel because it's a very tight tolerance -- I can barely slip a paper towel into it to try to dry it.

Anyone have any experience or recommendations with this?

This website doesn't appear to provide a solid way forward, but one person states a rust converter may be useful.
https://terrylove.com/forums/index.php? ... tub.23553/

Some more detail: this house was a rental for about 20 years, and we're periodically finding out just how "handy" the handyman was who "fixed up" the place before the previous owners sold it to us. In the tub alone, I found out a few months back that the overflow connection wasn't actually connected to anything.. it was just an open hole to outside of the tub beneath the spout. I only looked into it because I heard dripping from behind the tub one day. Out of sight, out of mind. Due to a great stroke of luck, there wasn't any mold because apparently the tub's bottom is open to the bottom of the house, so it was continuously vented. Apparently that isn't too uncommon out here.
Aloha,
Had a zillion apartments in Hawaii for decades and this was a constant problem. City Mill carries lousy tub and tub and tile caulking. The one in the red squeeze tube has silicone in it and is a bit better. After clean and dry, cut the tip at 90 degrees and make it large. Do a smooth caulk job around the tub like you see pros do on windows. Don't touch it. It should look like a smooth fine welding seam. Be sure it more than covers at 45 degrees the tub and well over the rust area and also up the tile wall. Should look very pro not "goopy" or "lumpy".
Once the tub starts rusting like this, you can only scrape and clean and dry it to best effect. Rust treatments last a little longer but risk staining the tub.
Salt in the air (especially windward side) and high humidity are the culprits. Plus so many bathrooms in Hawaii have poor ventilation or small windows.
A quality silicon caulk at City Mill or Home Depot or Ace in Kaimuki or Kaneohe will do the job. Comes in clear or white. Do not use "latex" based caulk as it will not last for very long at all.
Hope this helps.
Mahalo Nui Loa
j.

Cunobelinus
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Re: Home maintenance question - rust beneath caulk in tub

Post by Cunobelinus » Thu Jul 19, 2018 9:00 pm

Yeah, Kailua here. I attempted a recaulk a while ago, but the before the caulk was dry, it was already turning rust-colored. I do wonder if I tried a latex caulk then. The one I got for this job is silicone though, for sure.

We have central AC, which I thought may actually exacerbate the issue: the bottom of the tub is exposed directly to underside of the house and thus the high humidity and temperatures, while the inside of the tub is in an air conditioned environment.

Is there any point to really trying to get a silicone-based caulk all the way back in there, so as to preclude the tub's metal edge from even being exposed to the elements? I could try accessing it from the bottom of the house. If it's not possible for air and humidity to reach the metal, it can't oxidize it, right? :happy

Cunobelinus
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Re: Home maintenance question - rust beneath caulk in tub

Post by Cunobelinus » Thu Jul 19, 2018 9:04 pm

Sandtrap wrote:
Thu Jul 19, 2018 8:26 pm
Once the tub starts rusting like this, you can only scrape and clean and dry it to best effect. Rust treatments last a little longer but risk staining the tub.
Rust converters get a lot of good press in this situation, but the tolerances between the tub and the wall are fairly small. I don't know that I'll easily get an acid brush in there.

When you say scraping it clean, are you referring to using sandpaper, or something else?

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Sandtrap
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Re: Home maintenance question - rust beneath caulk in tub

Post by Sandtrap » Thu Jul 19, 2018 10:33 pm

Cunobelinus wrote:
Thu Jul 19, 2018 9:04 pm
Sandtrap wrote:
Thu Jul 19, 2018 8:26 pm
Once the tub starts rusting like this, you can only scrape and clean and dry it to best effect. Rust treatments last a little longer but risk staining the tub.
Rust converters get a lot of good press in this situation, but the tolerances between the tub and the wall are fairly small. I don't know that I'll easily get an acid brush in there.

When you say scraping it clean, are you referring to using sandpaper, or something else?
I used to live in Kaneohe and Kailua. (Kahoa Drive, Aoloa Street, etc).
First when it comes to rust on the Windward Side. . . . There's no hope. :shock:

Good news is "True Value Hardware" is close to you and has some good quality silicone caulking.

The salt air is brutal and permeates everything. Door hinges rust off the wall. Computer circuit boards and innards are toast. Let alone cars. And, the humidity makes it worse.

Even if the tolerances are small, scrape away and sand as best you can down to clear metal. Prime with metal primer if you care to. Then put a really nice thick bead of silicone caulk around the tub. If you use rust converter, just let it soak into the gap and then proceed.
If a tub get's really nasty and you don't want to replace it, you can call Epoxy Coating Systems Hawaii or something like that. They will spray a nasty smelling epoxy coating of various colors you choose on the tub and shower stall. It is a less expensive alternative to tearing out a tub and all that. This is when the tub is rusty and discolored everywhere. Many of the condo high rises and so forth use the Epoxy coating systems instead of ripping out tubs. When done well, it is acceptable and puts off the inevitable pricey remodel.

Good luck.
jim

f35phixer
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Re: Home maintenance question - rust beneath caulk in tub

Post by f35phixer » Fri Jul 20, 2018 5:03 am

you all are trying to scare us from moving there, I get it !!!!!!!!!!!!!

The whole house will rust from under you :D

Chip
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Re: Home maintenance question - rust beneath caulk in tub

Post by Chip » Fri Jul 20, 2018 6:59 am

2comma wrote:
Thu Jul 19, 2018 5:59 pm
Take a look at POR-15. If you get any loose stuff off it will definately stick to rust and protect it. It can be painted over but within a certain time period and only with certain paints so not sure your enamal repair kit is compatable. Just an idea to look into. You know what they say, "rust never sleeps" so you may be fighting a rear guard action on this one. Good luck!
Here's another vote for POR-15. I used it on a slightly rusted automobile frame with very good results. It looked as good as new 10 years later.

If I remember correctly the only surface prep I did was to remove all loose rust, grease, etc. (I used a wire wheel in a drill plus a solvent afterwards). Looking at the website now they have a "system" of chemicals to use for prep. I also see that they have a gloss white topcoat that might work well on a tub.

They sell it at Larry's Auto Parts in Honolulu, plus some other parts stores. You can look them up on the website.

I agree with Sandtrap's suggestion to use 100% silicone caulk. I prefer Type I but some don't like the acetic acid smell released during the curing process and go for Type 2 instead. I would suggest buying one with a mold/mildew inhibitor as well. Remember, 100% silicone, not "with silicone". You have to be careful of labeling. :)

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Sandtrap
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Re: Home maintenance question - rust beneath caulk in tub

Post by Sandtrap » Sat Jul 21, 2018 11:24 am

f35phixer wrote:
Fri Jul 20, 2018 5:03 am
you all are trying to scare us from moving there, I get it !!!!!!!!!!!!!

The whole house will rust from under you :D
Every area's climate has it's issues. In the Southwest, extreme dryness. In Hawaii, the opposite.
There are certain areas of Hawaii, usually on the "Windward Side" of an island along the coast where the steady and sometimes strong trade winds relentlessly drive salt air into the area. Cars rust out long before mechanical failure. Door hinges rust out prematurely. Aluminum window frames, and steel, are destroyed. On poorly painted homes, siding nails bleed rust. And, even computer innards take a beating. Even rebar rusts beneath the cement on concrete high rises. But, there is a 180 difference on the "Leeward" side of the islands. Sort of like OP's Kailua vs Honolulu, or Hilo (Big Island) vs Kona.

Funny story. A friend in Kailua had a study room with a 2 interior door entry. He only used one door forever. One day he was going to clean out the room and opened the long unused door. It fell off the hinges to the floor. :shock: That's Kailua rust. We replaced all the door hinges in his house with stainless steel. Great thereafter.

So, as long as one builds correctly and adapts to the tropical moisture and salt air, things are great.
I minor problem though, for living in beautiful and exotic Hawaii (No Ka Oi).
mahalo
j :D

Someone mentioned "Ospho". It works pretty well. Had some heavy steel staircases repainted and the contractors pretreated with "Ospho". It's held up quite well, even in Kaneohe.
Did not know about "PQR 15", may suggest that to some of my friends living in Kailua. Thanks.

Cunobelinus
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Re: Home maintenance question - rust beneath caulk in tub

Post by Cunobelinus » Thu Sep 20, 2018 5:57 am

I effected an 80% fix, by my estimation. I couldn't satisfactorily remove all of the rust. I ended up loading up the faucet-side of the tub with waaaaaay more silicone caulk than I thought necessary, and it looks a lot better. I was hoping the volume of caulk would provide a reasonable barrier against further corrosion, and it was at least 50% effective based on the brown rusty spots visible now.

This may be one of those things I commission a professional before if we rent/sell the house.

Thanks to all -- appreciate the feedback =)

And this corrosion stuff shouldn't scare you away. But the centipedes should: https://www.google.com/search?q=asian+r ... 22&bih=734 These buggahs are no joke.

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