What Paint To Use For painting Under The Tub?

B

Bitar100

TJ Enthusiast
Original poster
Joined
Dec 29, 2019
Messages
184
Location
San Diego
I have already started sanding and wire brushing the frame, suspension, and the underside of the tub.

I’m not sure what paint to use on the tub.

I’m planning to use Krylon Rust Tough Enamel Paint for the frame and suspension but the tub itself has rusted areas. Will that paint suffice or I will need to get Krylons primer Rust Enough version since there is still paint on the tub?

What do you guys recommend using for painting underneath of the tub?
 
  • Like
Reactions: Christian.mers
Just commenting to follow this thread.

Keen to see the answers here too as I'm about to undertake a similar process. I don't have any rust other than some on the corner of the stock rear bumper. I've seen a lot of folks talk about using POR-15 on the frame, and I've also heard Eastwood Chassis Black is good (goes a long way, so I hear), but I think is intended for motorcycle frames. Neither are easily accessible for me in Australia, so I'm looking at using a tin of Rustoleum Protective Enamel semi-gloss to brighten things up and improve appearance.
 
  • Like
Reactions: tm dean
While prep is key
Paint absolutely matters

If that were not the case, bedliner, and undercarrage coatings would have never been a viable business

High zinc, oil based for best results (cold galvanizing)
At the bare minimum I would use Rustoleum Professional silver can, and or this https://www.amazon.com/Rust-Oleum-2...Undercoating/dp/B08KRLS32P?tag=wranglerorg-20

My preferred final coat is called RP-342
This is an industrial / military grade wax coating
https://www.cosmolinedirect.com/cosmoline-rp-342-heavy-spray-military-grade-rust-preventive/

The English use a product called WaxOyl on their top emd vehicles like Range Rovers
 
Last edited:
Bitar100 said:
What do you guys recommend using for painting underneath of the tub?
Click to expand...

If you're going the rattle-can or brush-on route, I like Rustoleum Rusty Metal Primer followed by what ever top coat you want, typically in a semi-gloss. But like JMT said, make sure all the rust is gone, and the surfaces are scuffed and cleaned before painting.
 
Fluid film is better then NOTHING but its typically a short lifespan annual upkeep required product that has a buildup. Its great for inner body panels, and inner frame especially.

However for underbody, outer frame, erc
Theres better options that last waaay longer

We just had a member asking about a frame on a TJ he wanted to buy with uber goober fluid film buildup that was impossible to tell if the frame was ok.

Trying to identify and repair any underbody parts sprayed repeatedly is challenging
 
  • Like
Reactions: matkal
Bitar100 said:
I have already started sanding and wire brushing the frame, suspension, and the underside of the tub.

I’m not sure what paint to use on the tub.

I’m planning to use Krylon Rust Tough Enamel Paint for the frame and suspension but the tub itself has rusted areas. Will that paint suffice or I will need to get Krylons primer Rust Enough version since there is still paint on the tub?

What do you guys recommend using for painting underneath of the tub?
Click to expand...
There will be a lot of areas where you can't remove the rust completely. Look at something like the KBS Coatings conversion primer to slow down how much the rust will continue. Their top coat is pretty stellar in the satin for frames. Not fond of the price but it looks pretty good when you are done.
DSC02638.JPG
DSC02641.JPG
 
  • Like
Reactions: ColoJeep, Bitar100, RocknLJ and 5 others
for areas where fully removing all rust is impractical, if you can knock off the chunks and get it down to just light surface rust, I like phosphoric acid. It converts the rust to ferric phosphate which is black and doesn't rust, so it basically converts the rust into corrosion resistant, paintable coating. The stuff I use is called OSPHO and I got it in the paint department at Ace Hardware.

Just make sure you either a) brush it on, or b) wear full chemical PPE with goggles and a respirator if you're going to spray it. You don't want that stuff aerosolized into the air you're breathing.
 
  • Like
Reactions: Bitar100, AdelaideTJ and SSTJ
freedom_in_4low said:
for areas where fully removing all rust is impractical, if you can knock off the chunks and get it down to just light surface rust, I like phosphoric acid. It converts the rust to ferric phosphate which is black and doesn't rust, so it basically converts the rust into corrosion resistant, paintable coating. The stuff I use is called OSPHO and I got it in the paint department at Ace Hardware.

Just make sure you either a) brush it on, or b) wear full chemical PPE with goggles and a respirator if you're going to spray it. You don't want that stuff aerosolized into the air you're breathing.
Click to expand...

The problem with that shit is you have to keep the area wet for about 30 minutes and most of it has very strict warnings to not let it dry on the surface. Likely about the last fucking thing I would every try under a tub but if you're volunteering, I'll buy the PPE for you.
 
  • Like
Reactions: bluescapegoat and AdelaideTJ
mrblaine said:
The problem with that shit is you have to keep the area wet for about 30 minutes and most of it has very strict warnings to not let it dry on the surface. Likely about the last fucking thing I would every try under a tub but if you're volunteering, I'll buy the PPE for you.
Click to expand...

That may be true with stronger acid products but Ospho's instructions seem to state the opposite.

https://www.ospho.com/directions.htm#:~:text=RUSTED METALS - OSPHO is a,pre-diluted in the container

RUSTED METALS - OSPHO is a rust-inhibiting coating - NOT A PAINT You do not have to remove tight rust. Merely remove loose paint and rust scale, dirt, oil, grease and other accumulations with a wire brush or pressure washer and let dry - apply a thin coat of OSPHO as it comes pre-diluted in the container. Let dry overnight for a minimum of 24 hours, then apply whatever paint. Longer dry times may occur depending on temperature, humidity and over-application of product. OSPHO has the consistency of water and treats up to 600 square feet per gallon. When applied to rusted surfaces, OSPHO causes iron oxide (rust) to chemically change to iron phosphate - an inert, hard substance that turns the metal black. Where rust is exceedingly heavy, two coats of OSPHO may be necessary to thoroughly penetrate and blacken the surface to be painted. A dry, powdery, grayish-white surface usually develops when cured. Brush off any loose powder and wipe down with Mineral Spirits before painting.
Click to expand...

I've never had an issue with it staying wet for quite a while (hours), though I probably haven't used it anywhere quite as arid as southern California. There are versions that are more jelly-like that should help address that, as well as making it less drippy for applying to the bottom of a tub.
 
  • Like
Reactions: SSTJ
freedom_in_4low said:
That may be true with stronger acid products but Ospho's instructions seem to state the opposite.

https://www.ospho.com/directions.htm#:~:text=RUSTED METALS - OSPHO is a,pre-diluted in the container



I've never had an issue with it staying wet for quite a while (hours), though I probably haven't used it anywhere quite as arid as southern California. There are versions that are more jelly-like that should help address that, as well as making it less drippy for applying to the bottom of a tub.
Click to expand...
That is retarded. I use a phosphoric acid based product that states the exact opposite which is why I don't use it in difficult spots. I checked it again, has to stay wet 30 minutes for light rust, 1 hour for heavier, 2 hours for heavy rust. That is not gonna happen.
 
mrblaine said:
That is retarded. I use a phosphoric acid based product that states the exact opposite which is why I don't use it in difficult spots. I checked it again, has to stay wet 30 minutes for light rust, 1 hour for heavier, 2 hours for heavy rust. That is not gonna happen.
Click to expand...

I've used SEM Rust Mort and the directions state;

APPLICATION:
BRUSHING:
Apply multiple coats, keeping the area wet with Rust Mort until all rust is converted or removed. The longer the
surface is kept wet, the better the final result. After completion, remove any excess or non-converted Rust Mort
by rinsing with water and a brush. Make certain all surfaces are completely dry before proceeding with body filler
or primer per manufacturer’s recommendations. Failure to remove excess material can result in loss of adhesion of
subsequent top coats. Limit exposure after drying the surface to eliminate flash rust.

https://semproducts.com/public/content/techsheets/sem_tds_rust-mort.pdf

So yeah, you have to keep these products wet, at least the stuff I'm familiar with. It's that or completely submerge it. Rust Mort works well, but it's strong enough to etch into concrete if left unchecked. You have to neutralize Rust Mort.
 
mrblaine said:
There will be a lot of areas where you can't remove the rust completely. Look at something like the KBS Coatings conversion primer to slow down how much the rust will continue. Their top coat is pretty stellar in the satin for frames. Not fond of the price but it looks pretty good when you are done.
View attachment 539838View attachment 539839
Click to expand...
You are the man Mr. Blaine! Just Ordered 3 Cans of the primer hopefully that’s enough. Im hoping the Krylon Rust Enough and the KBS Conv Primer should do the job. You think they will work with each other?


KBS top coat is really nice but that price is ridiculous, I bought 6 cans of Krylon for the price of 1 can.
 
Top Bottom